完成微波仿真、点云构网、模型导出、仿真成像功能移植

extlib/Python/LICENSE.txt

@@ -59,6 +59,17 @@ direction to make these releases possible.
 B. TERMS AND CONDITIONS FOR ACCESSING OR OTHERWISE USING PYTHON
 ===============================================================
 
+Python software and documentation are licensed under the
+Python Software Foundation License Version 2.
+
+Starting with Python 3.8.6, examples, recipes, and other code in
+the documentation are dual licensed under the PSF License Version 2
+and the Zero-Clause BSD license.
+
+Some software incorporated into Python is under different licenses.
+The licenses are listed with code falling under that license.
+
+
 PYTHON SOFTWARE FOUNDATION LICENSE VERSION 2
 --------------------------------------------
 
@@ -73,8 +84,8 @@ analyze, test, perform and/or display publicly, prepare derivative works,
 distribute, and otherwise use Python alone or in any derivative version,
 provided, however, that PSF's License Agreement and PSF's notice of copyright,
 i.e., "Copyright (c) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010,
-2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018 Python Software Foundation; All
+2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021, 2022, 2023 Python Software Foundation;
-Rights Reserved" are retained in Python alone or in any derivative version
+All Rights Reserved" are retained in Python alone or in any derivative version
 prepared by Licensee.
 
 3. In the event Licensee prepares a derivative work that is based on
@@ -253,351 +264,16 @@ WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
 OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 
-
+ZERO-CLAUSE BSD LICENSE FOR CODE IN THE PYTHON DOCUMENTATION
-
-Additional Conditions for this Windows binary build
----------------------------------------------------
-
-This program is linked with and uses Microsoft Distributable Code,
-copyrighted by Microsoft Corporation. The Microsoft Distributable Code
-is embedded in each .exe, .dll and .pyd file as a result of running
-the code through a linker.
-
-If you further distribute programs that include the Microsoft
-Distributable Code, you must comply with the restrictions on
-distribution specified by Microsoft. In particular, you must require
-distributors and external end users to agree to terms that protect the
-Microsoft Distributable Code at least as much as Microsoft's own
-requirements for the Distributable Code. See Microsoft's documentation
-(included in its developer tools and on its website at microsoft.com)
-for specific details.
-
-Redistribution of the Windows binary build of the Python interpreter
-complies with this agreement, provided that you do not:
-
-- alter any copyright, trademark or patent notice in Microsoft's
-Distributable Code;
-
-- use Microsoft's trademarks in your programs' names or in a way that
-suggests your programs come from or are endorsed by Microsoft;
-
-- distribute Microsoft's Distributable Code to run on a platform other
-than Microsoft operating systems, run-time technologies or application
-platforms; or
-
-- include Microsoft Distributable Code in malicious, deceptive or
-unlawful programs.
-
-These restrictions apply only to the Microsoft Distributable Code as
-defined above, not to Python itself or any programs running on the
-Python interpreter. The redistribution of the Python interpreter and
-libraries is governed by the Python Software License included with this
-file, or by other licenses as marked.
-
-
-
---------------------------------------------------------------------------
-
-This program, "bzip2", the associated library "libbzip2", and all
-documentation, are copyright (C) 1996-2010 Julian R Seward.  All
-rights reserved.
-
-Redistribution and use in source and binary forms, with or without
-modification, are permitted provided that the following conditions
-are met:
-
-1. Redistributions of source code must retain the above copyright
-   notice, this list of conditions and the following disclaimer.
-
-2. The origin of this software must not be misrepresented; you must 
-   not claim that you wrote the original software.  If you use this 
-   software in a product, an acknowledgment in the product 
-   documentation would be appreciated but is not required.
-
-3. Altered source versions must be plainly marked as such, and must
-   not be misrepresented as being the original software.
-
-4. The name of the author may not be used to endorse or promote 
-   products derived from this software without specific prior written 
-   permission.
-
-THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
-OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
-WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
-ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
-DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
-DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
-GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
-INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
-WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
-NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
-SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-Julian Seward, jseward@bzip.org
-bzip2/libbzip2 version 1.0.6 of 6 September 2010
-
---------------------------------------------------------------------------
-
-
-  LICENSE ISSUES
-  ==============
-
-  The OpenSSL toolkit stays under a double license, i.e. both the conditions of
-  the OpenSSL License and the original SSLeay license apply to the toolkit.
-  See below for the actual license texts.
-
-  OpenSSL License
-  ---------------
-
-/* ====================================================================
- * Copyright (c) 1998-2018 The OpenSSL Project.  All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer. 
- *
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in
- *    the documentation and/or other materials provided with the
- *    distribution.
- *
- * 3. All advertising materials mentioning features or use of this
- *    software must display the following acknowledgment:
- *    "This product includes software developed by the OpenSSL Project
- *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
- *
- * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
- *    endorse or promote products derived from this software without
- *    prior written permission. For written permission, please contact
- *    openssl-core@openssl.org.
- *
- * 5. Products derived from this software may not be called "OpenSSL"
- *    nor may "OpenSSL" appear in their names without prior written
- *    permission of the OpenSSL Project.
- *
- * 6. Redistributions of any form whatsoever must retain the following
- *    acknowledgment:
- *    "This product includes software developed by the OpenSSL Project
- *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
- *
- * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
- * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
- * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
- * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
- * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
- * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
- * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
- * OF THE POSSIBILITY OF SUCH DAMAGE.
- * ====================================================================
- *
- * This product includes cryptographic software written by Eric Young
- * (eay@cryptsoft.com).  This product includes software written by Tim
- * Hudson (tjh@cryptsoft.com).
- *
- */
-
- Original SSLeay License
- -----------------------
-
-/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
- * All rights reserved.
- *
- * This package is an SSL implementation written
- * by Eric Young (eay@cryptsoft.com).
- * The implementation was written so as to conform with Netscapes SSL.
- * 
- * This library is free for commercial and non-commercial use as long as
- * the following conditions are aheared to.  The following conditions
- * apply to all code found in this distribution, be it the RC4, RSA,
- * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
- * included with this distribution is covered by the same copyright terms
- * except that the holder is Tim Hudson (tjh@cryptsoft.com).
- * 
- * Copyright remains Eric Young's, and as such any Copyright notices in
- * the code are not to be removed.
- * If this package is used in a product, Eric Young should be given attribution
- * as the author of the parts of the library used.
- * This can be in the form of a textual message at program startup or
- * in documentation (online or textual) provided with the package.
- * 
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- * 3. All advertising materials mentioning features or use of this software
- *    must display the following acknowledgement:
- *    "This product includes cryptographic software written by
- *     Eric Young (eay@cryptsoft.com)"
- *    The word 'cryptographic' can be left out if the rouines from the library
- *    being used are not cryptographic related :-).
- * 4. If you include any Windows specific code (or a derivative thereof) from 
- *    the apps directory (application code) you must include an acknowledgement:
- *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
- * 
- * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- * 
- * The licence and distribution terms for any publically available version or
- * derivative of this code cannot be changed.  i.e. this code cannot simply be
- * copied and put under another distribution licence
- * [including the GNU Public Licence.]
- */
-
-
-This software is copyrighted by the Regents of the University of
-California, Sun Microsystems, Inc., Scriptics Corporation, ActiveState
-Corporation and other parties.  The following terms apply to all files
-associated with the software unless explicitly disclaimed in
-individual files.
-
-The authors hereby grant permission to use, copy, modify, distribute,
-and license this software and its documentation for any purpose, provided
-that existing copyright notices are retained in all copies and that this
-notice is included verbatim in any distributions. No written agreement,
-license, or royalty fee is required for any of the authorized uses.
-Modifications to this software may be copyrighted by their authors
-and need not follow the licensing terms described here, provided that
-the new terms are clearly indicated on the first page of each file where
-they apply.
-
-IN NO EVENT SHALL THE AUTHORS OR DISTRIBUTORS BE LIABLE TO ANY PARTY
-FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
-ARISING OUT OF THE USE OF THIS SOFTWARE, ITS DOCUMENTATION, OR ANY
-DERIVATIVES THEREOF, EVEN IF THE AUTHORS HAVE BEEN ADVISED OF THE
-POSSIBILITY OF SUCH DAMAGE.
-
-THE AUTHORS AND DISTRIBUTORS SPECIFICALLY DISCLAIM ANY WARRANTIES,
-INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY,
-FITNESS FOR A PARTICULAR PURPOSE, AND NON-INFRINGEMENT.  THIS SOFTWARE
-IS PROVIDED ON AN "AS IS" BASIS, AND THE AUTHORS AND DISTRIBUTORS HAVE
-NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR
-MODIFICATIONS.
-
-GOVERNMENT USE: If you are acquiring this software on behalf of the
-U.S. government, the Government shall have only "Restricted Rights"
-in the software and related documentation as defined in the Federal
-Acquisition Regulations (FARs) in Clause 52.227.19 (c) (2).  If you
-are acquiring the software on behalf of the Department of Defense, the
-software shall be classified as "Commercial Computer Software" and the
-Government shall have only "Restricted Rights" as defined in Clause
-252.227-7014 (b) (3) of DFARs.  Notwithstanding the foregoing, the
-authors grant the U.S. Government and others acting in its behalf
-permission to use and distribute the software in accordance with the
-terms specified in this license.
-
-This software is copyrighted by the Regents of the University of
-California, Sun Microsystems, Inc., Scriptics Corporation, ActiveState
-Corporation, Apple Inc. and other parties.  The following terms apply to
-all files associated with the software unless explicitly disclaimed in
-individual files.
-
-The authors hereby grant permission to use, copy, modify, distribute,
-and license this software and its documentation for any purpose, provided
-that existing copyright notices are retained in all copies and that this
-notice is included verbatim in any distributions. No written agreement,
-license, or royalty fee is required for any of the authorized uses.
-Modifications to this software may be copyrighted by their authors
-and need not follow the licensing terms described here, provided that
-the new terms are clearly indicated on the first page of each file where
-they apply.
-
-IN NO EVENT SHALL THE AUTHORS OR DISTRIBUTORS BE LIABLE TO ANY PARTY
-FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
-ARISING OUT OF THE USE OF THIS SOFTWARE, ITS DOCUMENTATION, OR ANY
-DERIVATIVES THEREOF, EVEN IF THE AUTHORS HAVE BEEN ADVISED OF THE
-POSSIBILITY OF SUCH DAMAGE.
-
-THE AUTHORS AND DISTRIBUTORS SPECIFICALLY DISCLAIM ANY WARRANTIES,
-INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY,
-FITNESS FOR A PARTICULAR PURPOSE, AND NON-INFRINGEMENT.  THIS SOFTWARE
-IS PROVIDED ON AN "AS IS" BASIS, AND THE AUTHORS AND DISTRIBUTORS HAVE
-NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR
-MODIFICATIONS.
-
-GOVERNMENT USE: If you are acquiring this software on behalf of the
-U.S. government, the Government shall have only "Restricted Rights"
-in the software and related documentation as defined in the Federal
-Acquisition Regulations (FARs) in Clause 52.227.19 (c) (2).  If you
-are acquiring the software on behalf of the Department of Defense, the
-software shall be classified as "Commercial Computer Software" and the
-Government shall have only "Restricted Rights" as defined in Clause
-252.227-7013 (b) (3) of DFARs.  Notwithstanding the foregoing, the
-authors grant the U.S. Government and others acting in its behalf
-permission to use and distribute the software in accordance with the
-terms specified in this license.
-
-Copyright (c) 1993-1999 Ioi Kim Lam.
-Copyright (c) 2000-2001 Tix Project Group.
-Copyright (c) 2004 ActiveState
-
-This software is copyrighted by the above entities
-and other parties.  The following terms apply to all files associated
-with the software unless explicitly disclaimed in individual files.
-
-The authors hereby grant permission to use, copy, modify, distribute,
-and license this software and its documentation for any purpose, provided
-that existing copyright notices are retained in all copies and that this
-notice is included verbatim in any distributions. No written agreement,
-license, or royalty fee is required for any of the authorized uses.
-Modifications to this software may be copyrighted by their authors
-and need not follow the licensing terms described here, provided that
-the new terms are clearly indicated on the first page of each file where
-they apply.
-
-IN NO EVENT SHALL THE AUTHORS OR DISTRIBUTORS BE LIABLE TO ANY PARTY
-FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
-ARISING OUT OF THE USE OF THIS SOFTWARE, ITS DOCUMENTATION, OR ANY
-DERIVATIVES THEREOF, EVEN IF THE AUTHORS HAVE BEEN ADVISED OF THE
-POSSIBILITY OF SUCH DAMAGE.
-
-THE AUTHORS AND DISTRIBUTORS SPECIFICALLY DISCLAIM ANY WARRANTIES,
-INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY,
-FITNESS FOR A PARTICULAR PURPOSE, AND NON-INFRINGEMENT.  THIS SOFTWARE
-IS PROVIDED ON AN "AS IS" BASIS, AND THE AUTHORS AND DISTRIBUTORS HAVE
-NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR
-MODIFICATIONS.
-
-GOVERNMENT USE: If you are acquiring this software on behalf of the
-U.S. government, the Government shall have only "Restricted Rights"
-in the software and related documentation as defined in the Federal 
-Acquisition Regulations (FARs) in Clause 52.227.19 (c) (2).  If you
-are acquiring the software on behalf of the Department of Defense, the
-software shall be classified as "Commercial Computer Software" and the
-Government shall have only "Restricted Rights" as defined in Clause
-252.227-7013 (c) (1) of DFARs.  Notwithstanding the foregoing, the
-authors grant the U.S. Government and others acting in its behalf
-permission to use and distribute the software in accordance with the
-terms specified in this license. 
-
 ----------------------------------------------------------------------
 
-Parts of this software are based on the Tcl/Tk software copyrighted by
+Permission to use, copy, modify, and/or distribute this software for any
-the Regents of the University of California, Sun Microsystems, Inc.,
+purpose with or without fee is hereby granted.
-and other parties. The original license terms of the Tcl/Tk software
-distribution is included in the file docs/license.tcltk.
-
-Parts of this software are based on the HTML Library software
-copyrighted by Sun Microsystems, Inc. The original license terms of
-the HTML Library software distribution is included in the file
-docs/license.html_lib.
 
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+PERFORMANCE OF THIS SOFTWARE.

extlib/Python/Lib/__future__.py

@@ -66,18 +66,20 @@ __all__ = ["all_feature_names"] + all_feature_names
 # code.h and used by compile.h, so that an editor search will find them here.
 # However, they're not exported in __all__, because they don't really belong to
 # this module.
-CO_NESTED            = 0x0010   # nested_scopes
+CO_NESTED = 0x0010                      # nested_scopes
-CO_GENERATOR_ALLOWED = 0        # generators (obsolete, was 0x1000)
+CO_GENERATOR_ALLOWED = 0                # generators (obsolete, was 0x1000)
-CO_FUTURE_DIVISION   = 0x2000   # division
+CO_FUTURE_DIVISION = 0x20000            # division
-CO_FUTURE_ABSOLUTE_IMPORT = 0x4000 # perform absolute imports by default
+CO_FUTURE_ABSOLUTE_IMPORT = 0x40000     # perform absolute imports by default
-CO_FUTURE_WITH_STATEMENT  = 0x8000   # with statement
+CO_FUTURE_WITH_STATEMENT = 0x80000      # with statement
-CO_FUTURE_PRINT_FUNCTION  = 0x10000   # print function
+CO_FUTURE_PRINT_FUNCTION = 0x100000     # print function
-CO_FUTURE_UNICODE_LITERALS = 0x20000 # unicode string literals
+CO_FUTURE_UNICODE_LITERALS = 0x200000   # unicode string literals
-CO_FUTURE_BARRY_AS_BDFL = 0x40000
+CO_FUTURE_BARRY_AS_BDFL = 0x400000
-CO_FUTURE_GENERATOR_STOP  = 0x80000 # StopIteration becomes RuntimeError in generators
+CO_FUTURE_GENERATOR_STOP = 0x800000     # StopIteration becomes RuntimeError in generators
-CO_FUTURE_ANNOTATIONS     = 0x100000  # annotations become strings at runtime
+CO_FUTURE_ANNOTATIONS = 0x1000000       # annotations become strings at runtime
+
 
 class _Feature:
+
     def __init__(self, optionalRelease, mandatoryRelease, compiler_flag):
         self.optional = optionalRelease
         self.mandatory = mandatoryRelease
@@ -88,7 +90,6 @@ class _Feature:
 
         This is a 5-tuple, of the same form as sys.version_info.
         """
-
         return self.optional
 
     def getMandatoryRelease(self):
@@ -97,7 +98,6 @@ class _Feature:
         This is a 5-tuple, of the same form as sys.version_info, or, if
         the feature was dropped, is None.
         """
-
         return self.mandatory
 
     def __repr__(self):
@@ -105,6 +105,7 @@ class _Feature:
                                   self.mandatory,
                                   self.compiler_flag))
 
+
 nested_scopes = _Feature((2, 1, 0, "beta",  1),
                          (2, 2, 0, "alpha", 0),
                          CO_NESTED)
@@ -134,7 +135,7 @@ unicode_literals = _Feature((2, 6, 0, "alpha", 2),
                             CO_FUTURE_UNICODE_LITERALS)
 
 barry_as_FLUFL = _Feature((3, 1, 0, "alpha", 2),
-                          (3, 9, 0, "alpha", 0),
+                          (4, 0, 0, "alpha", 0),
                           CO_FUTURE_BARRY_AS_BDFL)
 
 generator_stop = _Feature((3, 5, 0, "beta", 1),
@@ -142,5 +143,5 @@ generator_stop = _Feature((3, 5, 0, "beta", 1),
                           CO_FUTURE_GENERATOR_STOP)
 
 annotations = _Feature((3, 7, 0, "beta", 1),
-                       (4, 0, 0, "alpha", 0),
+                       (3, 10, 0, "alpha", 0),
                        CO_FUTURE_ANNOTATIONS)

extlib/Python/Lib/_collections_abc.py

@@ -9,6 +9,12 @@ Unit tests are in test_collections.
 from abc import ABCMeta, abstractmethod
 import sys
 
+GenericAlias = type(list[int])
+EllipsisType = type(...)
+def _f(): pass
+FunctionType = type(_f)
+del _f
+
 __all__ = ["Awaitable", "Coroutine",
            "AsyncIterable", "AsyncIterator", "AsyncGenerator",
            "Hashable", "Iterable", "Iterator", "Generator", "Reversible",
@@ -110,6 +116,8 @@ class Awaitable(metaclass=ABCMeta):
             return _check_methods(C, "__await__")
         return NotImplemented
 
+    __class_getitem__ = classmethod(GenericAlias)
+
 
 class Coroutine(Awaitable):
 
@@ -169,6 +177,8 @@ class AsyncIterable(metaclass=ABCMeta):
             return _check_methods(C, "__aiter__")
         return NotImplemented
 
+    __class_getitem__ = classmethod(GenericAlias)
+
 
 class AsyncIterator(AsyncIterable):
 
@@ -255,6 +265,8 @@ class Iterable(metaclass=ABCMeta):
             return _check_methods(C, "__iter__")
         return NotImplemented
 
+    __class_getitem__ = classmethod(GenericAlias)
+
 
 class Iterator(Iterable):
 
@@ -274,6 +286,7 @@ class Iterator(Iterable):
             return _check_methods(C, '__iter__', '__next__')
         return NotImplemented
 
+
 Iterator.register(bytes_iterator)
 Iterator.register(bytearray_iterator)
 #Iterator.register(callable_iterator)
@@ -353,6 +366,7 @@ class Generator(Iterator):
                                   'send', 'throw', 'close')
         return NotImplemented
 
+
 Generator.register(generator)
 
 
@@ -385,6 +399,9 @@ class Container(metaclass=ABCMeta):
             return _check_methods(C, "__contains__")
         return NotImplemented
 
+    __class_getitem__ = classmethod(GenericAlias)
+
+
 class Collection(Sized, Iterable, Container):
 
     __slots__ = ()
@@ -395,6 +412,87 @@ class Collection(Sized, Iterable, Container):
             return _check_methods(C,  "__len__", "__iter__", "__contains__")
         return NotImplemented
 
+
+class _CallableGenericAlias(GenericAlias):
+    """ Represent `Callable[argtypes, resulttype]`.
+
+    This sets ``__args__`` to a tuple containing the flattened``argtypes``
+    followed by ``resulttype``.
+
+    Example: ``Callable[[int, str], float]`` sets ``__args__`` to
+    ``(int, str, float)``.
+    """
+
+    __slots__ = ()
+
+    def __new__(cls, origin, args):
+        try:
+            return cls.__create_ga(origin, args)
+        except TypeError as exc:
+            import warnings
+            warnings.warn(f'{str(exc)} '
+                          f'(This will raise a TypeError in Python 3.10.)',
+                          DeprecationWarning)
+            return GenericAlias(origin, args)
+
+    @classmethod
+    def __create_ga(cls, origin, args):
+        if not isinstance(args, tuple) or len(args) != 2:
+            raise TypeError(
+                "Callable must be used as Callable[[arg, ...], result].")
+        t_args, t_result = args
+        if isinstance(t_args, (list, tuple)):
+            ga_args = tuple(t_args) + (t_result,)
+        # This relaxes what t_args can be on purpose to allow things like
+        # PEP 612 ParamSpec.  Responsibility for whether a user is using
+        # Callable[...] properly is deferred to static type checkers.
+        else:
+            ga_args = args
+        return super().__new__(cls, origin, ga_args)
+
+    def __repr__(self):
+        if len(self.__args__) == 2 and self.__args__[0] is Ellipsis:
+            return super().__repr__()
+        return (f'collections.abc.Callable'
+                f'[[{", ".join([_type_repr(a) for a in self.__args__[:-1]])}], '
+                f'{_type_repr(self.__args__[-1])}]')
+
+    def __reduce__(self):
+        args = self.__args__
+        if not (len(args) == 2 and args[0] is Ellipsis):
+            args = list(args[:-1]), args[-1]
+        return _CallableGenericAlias, (Callable, args)
+
+    def __getitem__(self, item):
+        # Called during TypeVar substitution, returns the custom subclass
+        # rather than the default types.GenericAlias object.
+        ga = super().__getitem__(item)
+        args = ga.__args__
+        t_result = args[-1]
+        t_args = args[:-1]
+        args = (t_args, t_result)
+        return _CallableGenericAlias(Callable, args)
+
+
+def _type_repr(obj):
+    """Return the repr() of an object, special-casing types (internal helper).
+
+    Copied from :mod:`typing` since collections.abc
+    shouldn't depend on that module.
+    """
+    if isinstance(obj, GenericAlias):
+        return repr(obj)
+    if isinstance(obj, type):
+        if obj.__module__ == 'builtins':
+            return obj.__qualname__
+        return f'{obj.__module__}.{obj.__qualname__}'
+    if obj is Ellipsis:
+        return '...'
+    if isinstance(obj, FunctionType):
+        return obj.__name__
+    return repr(obj)
+
+
 class Callable(metaclass=ABCMeta):
 
     __slots__ = ()
@@ -409,6 +507,8 @@ class Callable(metaclass=ABCMeta):
             return _check_methods(C, "__call__")
         return NotImplemented
 
+    __class_getitem__ = classmethod(_CallableGenericAlias)
+
 
 ### SETS ###
 
@@ -542,6 +642,7 @@ class Set(Collection):
             hx = hash(x)
             h ^= (hx ^ (hx << 16) ^ 89869747)  * 3644798167
             h &= MASK
+        h ^= (h >> 11) ^ (h >> 25)
         h = h * 69069 + 907133923
         h &= MASK
         if h > MAX:
@@ -550,6 +651,7 @@ class Set(Collection):
             h = 590923713
         return h
 
+
 Set.register(frozenset)
 
 
@@ -632,6 +734,7 @@ class MutableSet(Set):
                 self.discard(value)
         return self
 
+
 MutableSet.register(set)
 
 
@@ -688,6 +791,7 @@ class Mapping(Collection):
 
     __reversed__ = None
 
+
 Mapping.register(mappingproxy)
 
 
@@ -704,13 +808,15 @@ class MappingView(Sized):
     def __repr__(self):
         return '{0.__class__.__name__}({0._mapping!r})'.format(self)
 
+    __class_getitem__ = classmethod(GenericAlias)
+
 
 class KeysView(MappingView, Set):
 
     __slots__ = ()
 
     @classmethod
-    def _from_iterable(self, it):
+    def _from_iterable(cls, it):
         return set(it)
 
     def __contains__(self, key):
@@ -719,6 +825,7 @@ class KeysView(MappingView, Set):
     def __iter__(self):
         yield from self._mapping
 
+
 KeysView.register(dict_keys)
 
 
@@ -727,7 +834,7 @@ class ItemsView(MappingView, Set):
     __slots__ = ()
 
     @classmethod
-    def _from_iterable(self, it):
+    def _from_iterable(cls, it):
         return set(it)
 
     def __contains__(self, item):
@@ -743,6 +850,7 @@ class ItemsView(MappingView, Set):
         for key in self._mapping:
             yield (key, self._mapping[key])
 
+
 ItemsView.register(dict_items)
 
 
@@ -761,6 +869,7 @@ class ValuesView(MappingView, Collection):
         for key in self._mapping:
             yield self._mapping[key]
 
+
 ValuesView.register(dict_values)
 
 
@@ -821,30 +930,21 @@ class MutableMapping(Mapping):
         except KeyError:
             pass
 
-    def update(*args, **kwds):
+    def update(self, other=(), /, **kwds):
         ''' D.update([E, ]**F) -> None.  Update D from mapping/iterable E and F.
             If E present and has a .keys() method, does:     for k in E: D[k] = E[k]
             If E present and lacks .keys() method, does:     for (k, v) in E: D[k] = v
             In either case, this is followed by: for k, v in F.items(): D[k] = v
         '''
-        if not args:
+        if isinstance(other, Mapping):
-            raise TypeError("descriptor 'update' of 'MutableMapping' object "
+            for key in other:
-                            "needs an argument")
+                self[key] = other[key]
-        self, *args = args
+        elif hasattr(other, "keys"):
-        if len(args) > 1:
+            for key in other.keys():
-            raise TypeError('update expected at most 1 arguments, got %d' %
+                self[key] = other[key]
-                            len(args))
+        else:
-        if args:
+            for key, value in other:
-            other = args[0]
+                self[key] = value
-            if isinstance(other, Mapping):
-                for key in other:
-                    self[key] = other[key]
-            elif hasattr(other, "keys"):
-                for key in other.keys():
-                    self[key] = other[key]
-            else:
-                for key, value in other:
-                    self[key] = value
         for key, value in kwds.items():
             self[key] = value
 
@@ -856,6 +956,7 @@ class MutableMapping(Mapping):
             self[key] = default
         return default
 
+
 MutableMapping.register(dict)
 
 
@@ -923,6 +1024,7 @@ class Sequence(Reversible, Collection):
         'S.count(value) -> integer -- return number of occurrences of value'
         return sum(1 for v in self if v is value or v == value)
 
+
 Sequence.register(tuple)
 Sequence.register(str)
 Sequence.register(range)
@@ -986,6 +1088,8 @@ class MutableSequence(Sequence):
 
     def extend(self, values):
         'S.extend(iterable) -- extend sequence by appending elements from the iterable'
+        if values is self:
+            values = list(values)
         for v in values:
             self.append(v)
 
@@ -1007,5 +1111,6 @@ class MutableSequence(Sequence):
         self.extend(values)
         return self
 
+
 MutableSequence.register(list)
 MutableSequence.register(bytearray)  # Multiply inheriting, see ByteString

extlib/Python/Lib/_dummy_thread.py

@@ -1,163 +0,0 @@
-"""Drop-in replacement for the thread module.
-
-Meant to be used as a brain-dead substitute so that threaded code does
-not need to be rewritten for when the thread module is not present.
-
-Suggested usage is::
-
-    try:
-        import _thread
-    except ImportError:
-        import _dummy_thread as _thread
-
-"""
-# Exports only things specified by thread documentation;
-# skipping obsolete synonyms allocate(), start_new(), exit_thread().
-__all__ = ['error', 'start_new_thread', 'exit', 'get_ident', 'allocate_lock',
-           'interrupt_main', 'LockType']
-
-# A dummy value
-TIMEOUT_MAX = 2**31
-
-# NOTE: this module can be imported early in the extension building process,
-# and so top level imports of other modules should be avoided.  Instead, all
-# imports are done when needed on a function-by-function basis.  Since threads
-# are disabled, the import lock should not be an issue anyway (??).
-
-error = RuntimeError
-
-def start_new_thread(function, args, kwargs={}):
-    """Dummy implementation of _thread.start_new_thread().
-
-    Compatibility is maintained by making sure that ``args`` is a
-    tuple and ``kwargs`` is a dictionary.  If an exception is raised
-    and it is SystemExit (which can be done by _thread.exit()) it is
-    caught and nothing is done; all other exceptions are printed out
-    by using traceback.print_exc().
-
-    If the executed function calls interrupt_main the KeyboardInterrupt will be
-    raised when the function returns.
-
-    """
-    if type(args) != type(tuple()):
-        raise TypeError("2nd arg must be a tuple")
-    if type(kwargs) != type(dict()):
-        raise TypeError("3rd arg must be a dict")
-    global _main
-    _main = False
-    try:
-        function(*args, **kwargs)
-    except SystemExit:
-        pass
-    except:
-        import traceback
-        traceback.print_exc()
-    _main = True
-    global _interrupt
-    if _interrupt:
-        _interrupt = False
-        raise KeyboardInterrupt
-
-def exit():
-    """Dummy implementation of _thread.exit()."""
-    raise SystemExit
-
-def get_ident():
-    """Dummy implementation of _thread.get_ident().
-
-    Since this module should only be used when _threadmodule is not
-    available, it is safe to assume that the current process is the
-    only thread.  Thus a constant can be safely returned.
-    """
-    return 1
-
-def allocate_lock():
-    """Dummy implementation of _thread.allocate_lock()."""
-    return LockType()
-
-def stack_size(size=None):
-    """Dummy implementation of _thread.stack_size()."""
-    if size is not None:
-        raise error("setting thread stack size not supported")
-    return 0
-
-def _set_sentinel():
-    """Dummy implementation of _thread._set_sentinel()."""
-    return LockType()
-
-class LockType(object):
-    """Class implementing dummy implementation of _thread.LockType.
-
-    Compatibility is maintained by maintaining self.locked_status
-    which is a boolean that stores the state of the lock.  Pickling of
-    the lock, though, should not be done since if the _thread module is
-    then used with an unpickled ``lock()`` from here problems could
-    occur from this class not having atomic methods.
-
-    """
-
-    def __init__(self):
-        self.locked_status = False
-
-    def acquire(self, waitflag=None, timeout=-1):
-        """Dummy implementation of acquire().
-
-        For blocking calls, self.locked_status is automatically set to
-        True and returned appropriately based on value of
-        ``waitflag``.  If it is non-blocking, then the value is
-        actually checked and not set if it is already acquired.  This
-        is all done so that threading.Condition's assert statements
-        aren't triggered and throw a little fit.
-
-        """
-        if waitflag is None or waitflag:
-            self.locked_status = True
-            return True
-        else:
-            if not self.locked_status:
-                self.locked_status = True
-                return True
-            else:
-                if timeout > 0:
-                    import time
-                    time.sleep(timeout)
-                return False
-
-    __enter__ = acquire
-
-    def __exit__(self, typ, val, tb):
-        self.release()
-
-    def release(self):
-        """Release the dummy lock."""
-        # XXX Perhaps shouldn't actually bother to test?  Could lead
-        #     to problems for complex, threaded code.
-        if not self.locked_status:
-            raise error
-        self.locked_status = False
-        return True
-
-    def locked(self):
-        return self.locked_status
-
-    def __repr__(self):
-        return "<%s %s.%s object at %s>" % (
-            "locked" if self.locked_status else "unlocked",
-            self.__class__.__module__,
-            self.__class__.__qualname__,
-            hex(id(self))
-        )
-
-# Used to signal that interrupt_main was called in a "thread"
-_interrupt = False
-# True when not executing in a "thread"
-_main = True
-
-def interrupt_main():
-    """Set _interrupt flag to True to have start_new_thread raise
-    KeyboardInterrupt upon exiting."""
-    if _main:
-        raise KeyboardInterrupt
-    else:
-        global _interrupt
-        _interrupt = True

extlib/Python/Lib/_markupbase.py

@@ -157,6 +157,7 @@ class ParserBase:
             match= _msmarkedsectionclose.search(rawdata, i+3)
         else:
             self.error('unknown status keyword %r in marked section' % rawdata[i+3:j])
+            match = None
         if not match:
             return -1
         if report:

extlib/Python/Lib/_osx_support.py

@@ -17,7 +17,7 @@ __all__ = [
 _UNIVERSAL_CONFIG_VARS = ('CFLAGS', 'LDFLAGS', 'CPPFLAGS', 'BASECFLAGS',
                             'BLDSHARED', 'LDSHARED', 'CC', 'CXX',
                             'PY_CFLAGS', 'PY_LDFLAGS', 'PY_CPPFLAGS',
-                            'PY_CORE_CFLAGS')
+                            'PY_CORE_CFLAGS', 'PY_CORE_LDFLAGS')
 
 # configuration variables that may contain compiler calls
 _COMPILER_CONFIG_VARS = ('BLDSHARED', 'LDSHARED', 'CC', 'CXX')
@@ -52,7 +52,7 @@ def _find_executable(executable, path=None):
         return executable
 
 
-def _read_output(commandstring):
+def _read_output(commandstring, capture_stderr=False):
     """Output from successful command execution or None"""
     # Similar to os.popen(commandstring, "r").read(),
     # but without actually using os.popen because that
@@ -67,7 +67,10 @@ def _read_output(commandstring):
             os.getpid(),), "w+b")
 
     with contextlib.closing(fp) as fp:
-        cmd = "%s 2>/dev/null >'%s'" % (commandstring, fp.name)
+        if capture_stderr:
+            cmd = "%s >'%s' 2>&1" % (commandstring, fp.name)
+        else:
+            cmd = "%s 2>/dev/null >'%s'" % (commandstring, fp.name)
         return fp.read().decode('utf-8').strip() if not os.system(cmd) else None
 
 
@@ -110,6 +113,26 @@ def _get_system_version():
 
     return _SYSTEM_VERSION
 
+_SYSTEM_VERSION_TUPLE = None
+def _get_system_version_tuple():
+    """
+    Return the macOS system version as a tuple
+
+    The return value is safe to use to compare
+    two version numbers.
+    """
+    global _SYSTEM_VERSION_TUPLE
+    if _SYSTEM_VERSION_TUPLE is None:
+        osx_version = _get_system_version()
+        if osx_version:
+            try:
+                _SYSTEM_VERSION_TUPLE = tuple(int(i) for i in osx_version.split('.'))
+            except ValueError:
+                _SYSTEM_VERSION_TUPLE = ()
+
+    return _SYSTEM_VERSION_TUPLE
+
+
 def _remove_original_values(_config_vars):
     """Remove original unmodified values for testing"""
     # This is needed for higher-level cross-platform tests of get_platform.
@@ -125,6 +148,33 @@ def _save_modified_value(_config_vars, cv, newvalue):
         _config_vars[_INITPRE + cv] = oldvalue
     _config_vars[cv] = newvalue
 
+
+_cache_default_sysroot = None
+def _default_sysroot(cc):
+    """ Returns the root of the default SDK for this system, or '/' """
+    global _cache_default_sysroot
+
+    if _cache_default_sysroot is not None:
+        return _cache_default_sysroot
+
+    contents = _read_output('%s -c -E -v - </dev/null' % (cc,), True)
+    in_incdirs = False
+    for line in contents.splitlines():
+        if line.startswith("#include <...>"):
+            in_incdirs = True
+        elif line.startswith("End of search list"):
+            in_incdirs = False
+        elif in_incdirs:
+            line = line.strip()
+            if line == '/usr/include':
+                _cache_default_sysroot = '/'
+            elif line.endswith(".sdk/usr/include"):
+                _cache_default_sysroot = line[:-12]
+    if _cache_default_sysroot is None:
+        _cache_default_sysroot = '/'
+
+    return _cache_default_sysroot
+
 def _supports_universal_builds():
     """Returns True if universal builds are supported on this system"""
     # As an approximation, we assume that if we are running on 10.4 or above,
@@ -132,14 +182,18 @@ def _supports_universal_builds():
     # builds, in particular -isysroot and -arch arguments to the compiler. This
     # is in support of allowing 10.4 universal builds to run on 10.3.x systems.
 
-    osx_version = _get_system_version()
+    osx_version = _get_system_version_tuple()
-    if osx_version:
-        try:
-            osx_version = tuple(int(i) for i in osx_version.split('.'))
-        except ValueError:
-            osx_version = ''
     return bool(osx_version >= (10, 4)) if osx_version else False
 
+def _supports_arm64_builds():
+    """Returns True if arm64 builds are supported on this system"""
+    # There are two sets of systems supporting macOS/arm64 builds:
+    # 1. macOS 11 and later, unconditionally
+    # 2. macOS 10.15 with Xcode 12.2 or later
+    # For now the second category is ignored.
+    osx_version = _get_system_version_tuple()
+    return osx_version >= (11, 0) if osx_version else False
+
 
 def _find_appropriate_compiler(_config_vars):
     """Find appropriate C compiler for extension module builds"""
@@ -211,7 +265,7 @@ def _remove_universal_flags(_config_vars):
         if cv in _config_vars and cv not in os.environ:
             flags = _config_vars[cv]
             flags = re.sub(r'-arch\s+\w+\s', ' ', flags, flags=re.ASCII)
-            flags = re.sub('-isysroot [^ \t]*', ' ', flags)
+            flags = re.sub(r'-isysroot\s*\S+', ' ', flags)
             _save_modified_value(_config_vars, cv, flags)
 
     return _config_vars
@@ -287,7 +341,7 @@ def _check_for_unavailable_sdk(_config_vars):
     # to /usr and /System/Library by either a standalone CLT
     # package or the CLT component within Xcode.
     cflags = _config_vars.get('CFLAGS', '')
-    m = re.search(r'-isysroot\s+(\S+)', cflags)
+    m = re.search(r'-isysroot\s*(\S+)', cflags)
     if m is not None:
         sdk = m.group(1)
         if not os.path.exists(sdk):
@@ -295,7 +349,7 @@ def _check_for_unavailable_sdk(_config_vars):
                 # Do not alter a config var explicitly overridden by env var
                 if cv in _config_vars and cv not in os.environ:
                     flags = _config_vars[cv]
-                    flags = re.sub(r'-isysroot\s+\S+(?:\s|$)', ' ', flags)
+                    flags = re.sub(r'-isysroot\s*\S+(?:\s|$)', ' ', flags)
                     _save_modified_value(_config_vars, cv, flags)
 
     return _config_vars
@@ -320,7 +374,7 @@ def compiler_fixup(compiler_so, cc_args):
         stripArch = stripSysroot = True
     else:
         stripArch = '-arch' in cc_args
-        stripSysroot = '-isysroot' in cc_args
+        stripSysroot = any(arg for arg in cc_args if arg.startswith('-isysroot'))
 
     if stripArch or 'ARCHFLAGS' in os.environ:
         while True:
@@ -331,6 +385,12 @@ def compiler_fixup(compiler_so, cc_args):
             except ValueError:
                 break
 
+    elif not _supports_arm64_builds():
+        # Look for "-arch arm64" and drop that
+        for idx in reversed(range(len(compiler_so))):
+            if compiler_so[idx] == '-arch' and compiler_so[idx+1] == "arm64":
+                del compiler_so[idx:idx+2]
+
     if 'ARCHFLAGS' in os.environ and not stripArch:
         # User specified different -arch flags in the environ,
         # see also distutils.sysconfig
@@ -338,23 +398,34 @@ def compiler_fixup(compiler_so, cc_args):
 
     if stripSysroot:
         while True:
-            try:
+            indices = [i for i,x in enumerate(compiler_so) if x.startswith('-isysroot')]
-                index = compiler_so.index('-isysroot')
+            if not indices:
+                break
+            index = indices[0]
+            if compiler_so[index] == '-isysroot':
                 # Strip this argument and the next one:
                 del compiler_so[index:index+2]
-            except ValueError:
+            else:
-                break
+                # It's '-isysroot/some/path' in one arg
+                del compiler_so[index:index+1]
 
     # Check if the SDK that is used during compilation actually exists,
     # the universal build requires the usage of a universal SDK and not all
     # users have that installed by default.
     sysroot = None
-    if '-isysroot' in cc_args:
+    argvar = cc_args
-        idx = cc_args.index('-isysroot')
+    indices = [i for i,x in enumerate(cc_args) if x.startswith('-isysroot')]
-        sysroot = cc_args[idx+1]
+    if not indices:
-    elif '-isysroot' in compiler_so:
+        argvar = compiler_so
-        idx = compiler_so.index('-isysroot')
+        indices = [i for i,x in enumerate(compiler_so) if x.startswith('-isysroot')]
-        sysroot = compiler_so[idx+1]
+
+    for idx in indices:
+        if argvar[idx] == '-isysroot':
+            sysroot = argvar[idx+1]
+            break
+        else:
+            sysroot = argvar[idx][len('-isysroot'):]
+            break
 
     if sysroot and not os.path.isdir(sysroot):
         from distutils import log
@@ -411,7 +482,7 @@ def customize_compiler(_config_vars):
 
     This customization is performed when the first
     extension module build is requested
-    in distutils.sysconfig.customize_compiler).
+    in distutils.sysconfig.customize_compiler.
     """
 
     # Find a compiler to use for extension module builds
@@ -470,6 +541,8 @@ def get_platform_osx(_config_vars, osname, release, machine):
 
             if len(archs) == 1:
                 machine = archs[0]
+            elif archs == ('arm64', 'x86_64'):
+                machine = 'universal2'
             elif archs == ('i386', 'ppc'):
                 machine = 'fat'
             elif archs == ('i386', 'x86_64'):

extlib/Python/Lib/_py_abc.py

@@ -32,7 +32,7 @@ class ABCMeta(type):
     #       external code.
     _abc_invalidation_counter = 0
 
-    def __new__(mcls, name, bases, namespace, **kwargs):
+    def __new__(mcls, name, bases, namespace, /, **kwargs):
         cls = super().__new__(mcls, name, bases, namespace, **kwargs)
         # Compute set of abstract method names
         abstracts = {name

extlib/Python/Lib/_pydecimal.py

@@ -140,8 +140,11 @@ __all__ = [
     # Limits for the C version for compatibility
     'MAX_PREC',  'MAX_EMAX', 'MIN_EMIN', 'MIN_ETINY',
 
-    # C version: compile time choice that enables the thread local context
+    # C version: compile time choice that enables the thread local context (deprecated, now always true)
-    'HAVE_THREADS'
+    'HAVE_THREADS',
+
+    # C version: compile time choice that enables the coroutine local context
+    'HAVE_CONTEXTVAR'
 ]
 
 __xname__ = __name__    # sys.modules lookup (--without-threads)
@@ -172,6 +175,7 @@ ROUND_05UP = 'ROUND_05UP'
 
 # Compatibility with the C version
 HAVE_THREADS = True
+HAVE_CONTEXTVAR = True
 if sys.maxsize == 2**63-1:
     MAX_PREC = 999999999999999999
     MAX_EMAX = 999999999999999999
@@ -2021,7 +2025,7 @@ class Decimal(object):
         if not other and not self:
             return context._raise_error(InvalidOperation,
                                         'at least one of pow() 1st argument '
-                                        'and 2nd argument must be nonzero ;'
+                                        'and 2nd argument must be nonzero; '
                                         '0**0 is not defined')
 
         # compute sign of result
@@ -5631,8 +5635,6 @@ class _WorkRep(object):
     def __repr__(self):
         return "(%r, %r, %r)" % (self.sign, self.int, self.exp)
 
-    __str__ = __repr__
-
 
 
 def _normalize(op1, op2, prec = 0):

extlib/Python/Lib/_pyio.py

@@ -33,6 +33,12 @@ DEFAULT_BUFFER_SIZE = 8 * 1024  # bytes
 # Rebind for compatibility
 BlockingIOError = BlockingIOError
 
+# Does io.IOBase finalizer log the exception if the close() method fails?
+# The exception is ignored silently by default in release build.
+_IOBASE_EMITS_UNRAISABLE = (hasattr(sys, "gettotalrefcount") or sys.flags.dev_mode)
+# Does open() check its 'errors' argument?
+_CHECK_ERRORS = _IOBASE_EMITS_UNRAISABLE
+
 
 def open(file, mode="r", buffering=-1, encoding=None, errors=None,
          newline=None, closefd=True, opener=None):
@@ -198,6 +204,11 @@ def open(file, mode="r", buffering=-1, encoding=None, errors=None,
         raise ValueError("binary mode doesn't take an errors argument")
     if binary and newline is not None:
         raise ValueError("binary mode doesn't take a newline argument")
+    if binary and buffering == 1:
+        import warnings
+        warnings.warn("line buffering (buffering=1) isn't supported in binary "
+                      "mode, the default buffer size will be used",
+                      RuntimeWarning, 2)
     raw = FileIO(file,
                  (creating and "x" or "") +
                  (reading and "r" or "") +
@@ -245,11 +256,34 @@ def open(file, mode="r", buffering=-1, encoding=None, errors=None,
         result.close()
         raise
 
+# Define a default pure-Python implementation for open_code()
+# that does not allow hooks. Warn on first use. Defined for tests.
+def _open_code_with_warning(path):
+    """Opens the provided file with mode ``'rb'``. This function
+    should be used when the intent is to treat the contents as
+    executable code.
+
+    ``path`` should be an absolute path.
+
+    When supported by the runtime, this function can be hooked
+    in order to allow embedders more control over code files.
+    This functionality is not supported on the current runtime.
+    """
+    import warnings
+    warnings.warn("_pyio.open_code() may not be using hooks",
+                  RuntimeWarning, 2)
+    return open(path, "rb")
+
+try:
+    open_code = io.open_code
+except AttributeError:
+    open_code = _open_code_with_warning
+
 
 class DocDescriptor:
     """Helper for builtins.open.__doc__
     """
-    def __get__(self, obj, typ):
+    def __get__(self, obj, typ=None):
         return (
             "open(file, mode='r', buffering=-1, encoding=None, "
                  "errors=None, newline=None, closefd=True)\n\n" +
@@ -280,23 +314,21 @@ except AttributeError:
 
 class IOBase(metaclass=abc.ABCMeta):
 
-    """The abstract base class for all I/O classes, acting on streams of
+    """The abstract base class for all I/O classes.
-    bytes. There is no public constructor.
 
     This class provides dummy implementations for many methods that
     derived classes can override selectively; the default implementations
     represent a file that cannot be read, written or seeked.
 
-    Even though IOBase does not declare read, readinto, or write because
+    Even though IOBase does not declare read or write because
     their signatures will vary, implementations and clients should
     consider those methods part of the interface. Also, implementations
     may raise UnsupportedOperation when operations they do not support are
     called.
 
     The basic type used for binary data read from or written to a file is
-    bytes. Other bytes-like objects are accepted as method arguments too. In
+    bytes. Other bytes-like objects are accepted as method arguments too.
-    some cases (such as readinto), a writable object is required. Text I/O
+    Text I/O classes work with str data.
-    classes work with str data.
 
     Note that calling any method (even inquiries) on a closed stream is
     undefined. Implementations may raise OSError in this case.
@@ -374,15 +406,28 @@ class IOBase(metaclass=abc.ABCMeta):
 
     def __del__(self):
         """Destructor.  Calls close()."""
-        # The try/except block is in case this is called at program
-        # exit time, when it's possible that globals have already been
-        # deleted, and then the close() call might fail.  Since
-        # there's nothing we can do about such failures and they annoy
-        # the end users, we suppress the traceback.
         try:
+            closed = self.closed
+        except AttributeError:
+            # If getting closed fails, then the object is probably
+            # in an unusable state, so ignore.
+            return
+
+        if closed:
+            return
+
+        if _IOBASE_EMITS_UNRAISABLE:
             self.close()
-        except:
+        else:
-            pass
+            # The try/except block is in case this is called at program
+            # exit time, when it's possible that globals have already been
+            # deleted, and then the close() call might fail.  Since
+            # there's nothing we can do about such failures and they annoy
+            # the end users, we suppress the traceback.
+            try:
+                self.close()
+            except:
+                pass
 
     ### Inquiries ###
 
@@ -547,6 +592,11 @@ class IOBase(metaclass=abc.ABCMeta):
         return lines
 
     def writelines(self, lines):
+        """Write a list of lines to the stream.
+
+        Line separators are not added, so it is usual for each of the lines
+        provided to have a line separator at the end.
+        """
         self._checkClosed()
         for line in lines:
             self.write(line)
@@ -753,6 +803,9 @@ class _BufferedIOMixin(BufferedIOBase):
         return pos
 
     def truncate(self, pos=None):
+        self._checkClosed()
+        self._checkWritable()
+
         # Flush the stream.  We're mixing buffered I/O with lower-level I/O,
         # and a flush may be necessary to synch both views of the current
         # file state.
@@ -809,15 +862,14 @@ class _BufferedIOMixin(BufferedIOBase):
         return self.raw.mode
 
     def __getstate__(self):
-        raise TypeError("can not serialize a '{0}' object"
+        raise TypeError(f"cannot pickle {self.__class__.__name__!r} object")
-                        .format(self.__class__.__name__))
 
     def __repr__(self):
         modname = self.__class__.__module__
         clsname = self.__class__.__qualname__
         try:
             name = self.name
-        except Exception:
+        except AttributeError:
             return "<{}.{}>".format(modname, clsname)
         else:
             return "<{}.{} name={!r}>".format(modname, clsname, name)
@@ -835,6 +887,10 @@ class BytesIO(BufferedIOBase):
 
     """Buffered I/O implementation using an in-memory bytes buffer."""
 
+    # Initialize _buffer as soon as possible since it's used by __del__()
+    # which calls close()
+    _buffer = None
+
     def __init__(self, initial_bytes=None):
         buf = bytearray()
         if initial_bytes is not None:
@@ -862,7 +918,8 @@ class BytesIO(BufferedIOBase):
         return memoryview(self._buffer)
 
     def close(self):
-        self._buffer.clear()
+        if self._buffer is not None:
+            self._buffer.clear()
         super().close()
 
     def read(self, size=-1):
@@ -1518,7 +1575,7 @@ class FileIO(RawIOBase):
                     raise IsADirectoryError(errno.EISDIR,
                                             os.strerror(errno.EISDIR), file)
             except AttributeError:
-                # Ignore the AttribueError if stat.S_ISDIR or errno.EISDIR
+                # Ignore the AttributeError if stat.S_ISDIR or errno.EISDIR
                 # don't exist.
                 pass
             self._blksize = getattr(fdfstat, 'st_blksize', 0)
@@ -1534,7 +1591,11 @@ class FileIO(RawIOBase):
                 # For consistent behaviour, we explicitly seek to the
                 # end of file (otherwise, it might be done only on the
                 # first write()).
-                os.lseek(fd, 0, SEEK_END)
+                try:
+                    os.lseek(fd, 0, SEEK_END)
+                except OSError as e:
+                    if e.errno != errno.ESPIPE:
+                        raise
         except:
             if owned_fd is not None:
                 os.close(owned_fd)
@@ -1549,7 +1610,7 @@ class FileIO(RawIOBase):
             self.close()
 
     def __getstate__(self):
-        raise TypeError("cannot serialize '%s' object", self.__class__.__name__)
+        raise TypeError(f"cannot pickle {self.__class__.__name__!r} object")
 
     def __repr__(self):
         class_name = '%s.%s' % (self.__class__.__module__,
@@ -1759,8 +1820,7 @@ class TextIOBase(IOBase):
     """Base class for text I/O.
 
     This class provides a character and line based interface to stream
-    I/O. There is no readinto method because Python's character strings
+    I/O.
-    are immutable. There is no public constructor.
     """
 
     def read(self, size=-1):
@@ -1933,6 +1993,10 @@ class TextIOWrapper(TextIOBase):
 
     _CHUNK_SIZE = 2048
 
+    # Initialize _buffer as soon as possible since it's used by __del__()
+    # which calls close()
+    _buffer = None
+
     # The write_through argument has no effect here since this
     # implementation always writes through.  The argument is present only
     # so that the signature can match the signature of the C version.
@@ -1966,6 +2030,8 @@ class TextIOWrapper(TextIOBase):
         else:
             if not isinstance(errors, str):
                 raise ValueError("invalid errors: %r" % errors)
+            if _CHECK_ERRORS:
+                codecs.lookup_error(errors)
 
         self._buffer = buffer
         self._decoded_chars = ''  # buffer for text returned from decoder
@@ -2023,13 +2089,13 @@ class TextIOWrapper(TextIOBase):
                                  self.__class__.__qualname__)
         try:
             name = self.name
-        except Exception:
+        except AttributeError:
             pass
         else:
             result += " name={0!r}".format(name)
         try:
             mode = self.mode
-        except Exception:
+        except AttributeError:
             pass
         else:
             result += " mode={0!r}".format(mode)
@@ -2149,6 +2215,7 @@ class TextIOWrapper(TextIOBase):
         self.buffer.write(b)
         if self._line_buffering and (haslf or "\r" in s):
             self.flush()
+        self._set_decoded_chars('')
         self._snapshot = None
         if self._decoder:
             self._decoder.reset()
@@ -2234,7 +2301,7 @@ class TextIOWrapper(TextIOBase):
         return not eof
 
     def _pack_cookie(self, position, dec_flags=0,
-                           bytes_to_feed=0, need_eof=0, chars_to_skip=0):
+                           bytes_to_feed=0, need_eof=False, chars_to_skip=0):
         # The meaning of a tell() cookie is: seek to position, set the
         # decoder flags to dec_flags, read bytes_to_feed bytes, feed them
         # into the decoder with need_eof as the EOF flag, then skip
@@ -2248,7 +2315,7 @@ class TextIOWrapper(TextIOBase):
         rest, dec_flags = divmod(rest, 1<<64)
         rest, bytes_to_feed = divmod(rest, 1<<64)
         need_eof, chars_to_skip = divmod(rest, 1<<64)
-        return position, dec_flags, bytes_to_feed, need_eof, chars_to_skip
+        return position, dec_flags, bytes_to_feed, bool(need_eof), chars_to_skip
 
     def tell(self):
         if not self._seekable:
@@ -2282,7 +2349,7 @@ class TextIOWrapper(TextIOBase):
             # current pos.
             # Rationale: calling decoder.decode() has a large overhead
             # regardless of chunk size; we want the number of such calls to
-            # be O(1) in most situations (common decoders, non-crazy input).
+            # be O(1) in most situations (common decoders, sensible input).
             # Actually, it will be exactly 1 for fixed-size codecs (all
             # 8-bit codecs, also UTF-16 and UTF-32).
             skip_bytes = int(self._b2cratio * chars_to_skip)
@@ -2322,7 +2389,7 @@ class TextIOWrapper(TextIOBase):
             # (a point where the decoder has nothing buffered, so seek()
             # can safely start from there and advance to this location).
             bytes_fed = 0
-            need_eof = 0
+            need_eof = False
             # Chars decoded since `start_pos`
             chars_decoded = 0
             for i in range(skip_bytes, len(next_input)):
@@ -2339,7 +2406,7 @@ class TextIOWrapper(TextIOBase):
             else:
                 # We didn't get enough decoded data; signal EOF to get more.
                 chars_decoded += len(decoder.decode(b'', final=True))
-                need_eof = 1
+                need_eof = True
                 if chars_decoded < chars_to_skip:
                     raise OSError("can't reconstruct logical file position")
 
@@ -2381,18 +2448,18 @@ class TextIOWrapper(TextIOBase):
             raise ValueError("tell on closed file")
         if not self._seekable:
             raise UnsupportedOperation("underlying stream is not seekable")
-        if whence == 1: # seek relative to current position
+        if whence == SEEK_CUR:
             if cookie != 0:
                 raise UnsupportedOperation("can't do nonzero cur-relative seeks")
             # Seeking to the current position should attempt to
             # sync the underlying buffer with the current position.
             whence = 0
             cookie = self.tell()
-        if whence == 2: # seek relative to end of file
+        elif whence == SEEK_END:
             if cookie != 0:
                 raise UnsupportedOperation("can't do nonzero end-relative seeks")
             self.flush()
-            position = self.buffer.seek(0, 2)
+            position = self.buffer.seek(0, whence)
             self._set_decoded_chars('')
             self._snapshot = None
             if self._decoder:

extlib/Python/Lib/_strptime.py

@@ -77,15 +77,6 @@ class LocaleTime(object):
         if time.tzname != self.tzname or time.daylight != self.daylight:
             raise ValueError("timezone changed during initialization")
 
-    def __pad(self, seq, front):
-        # Add '' to seq to either the front (is True), else the back.
-        seq = list(seq)
-        if front:
-            seq.insert(0, '')
-        else:
-            seq.append('')
-        return seq
-
     def __calc_weekday(self):
         # Set self.a_weekday and self.f_weekday using the calendar
         # module.
@@ -191,7 +182,7 @@ class TimeRE(dict):
             self.locale_time = LocaleTime()
         base = super()
         base.__init__({
-            # The " \d" part of the regex is to make %c from ANSI C work
+            # The " [1-9]" part of the regex is to make %c from ANSI C work
             'd': r"(?P<d>3[0-1]|[1-2]\d|0[1-9]|[1-9]| [1-9])",
             'f': r"(?P<f>[0-9]{1,6})",
             'H': r"(?P<H>2[0-3]|[0-1]\d|\d)",
@@ -210,7 +201,7 @@ class TimeRE(dict):
             #XXX: Does 'Y' need to worry about having less or more than
             #     4 digits?
             'Y': r"(?P<Y>\d\d\d\d)",
-            'z': r"(?P<z>[+-]\d\d:?[0-5]\d(:?[0-5]\d(\.\d{1,6})?)?|Z)",
+            'z': r"(?P<z>[+-]\d\d:?[0-5]\d(:?[0-5]\d(\.\d{1,6})?)?|(?-i:Z))",
             'A': self.__seqToRE(self.locale_time.f_weekday, 'A'),
             'a': self.__seqToRE(self.locale_time.a_weekday, 'a'),
             'B': self.__seqToRE(self.locale_time.f_month[1:], 'B'),

extlib/Python/Lib/_threading_local.py

@@ -56,7 +56,7 @@ You can create custom local objects by subclassing the local class:
 
   >>> class MyLocal(local):
   ...     number = 2
-  ...     def __init__(self, **kw):
+  ...     def __init__(self, /, **kw):
   ...         self.__dict__.update(kw)
   ...     def squared(self):
   ...         return self.number ** 2
@@ -204,7 +204,7 @@ def _patch(self):
 class local:
     __slots__ = '_local__impl', '__dict__'
 
-    def __new__(cls, *args, **kw):
+    def __new__(cls, /, *args, **kw):
         if (args or kw) and (cls.__init__ is object.__init__):
             raise TypeError("Initialization arguments are not supported")
         self = object.__new__(cls)

extlib/Python/Lib/_weakrefset.py

@@ -3,6 +3,7 @@
 # by abc.py to load everything else at startup.
 
 from _weakref import ref
+from types import GenericAlias
 
 __all__ = ['WeakSet']
 
@@ -50,10 +51,14 @@ class WeakSet:
             self.update(data)
 
     def _commit_removals(self):
-        l = self._pending_removals
+        pop = self._pending_removals.pop
         discard = self.data.discard
-        while l:
+        while True:
-            discard(l.pop())
+            try:
+                item = pop()
+            except IndexError:
+                return
+            discard(item)
 
     def __iter__(self):
         with _IterationGuard(self):
@@ -194,3 +199,8 @@ class WeakSet:
 
     def isdisjoint(self, other):
         return len(self.intersection(other)) == 0
+
+    def __repr__(self):
+        return repr(self.data)
+
+    __class_getitem__ = classmethod(GenericAlias)

extlib/Python/Lib/abc.py

@@ -11,7 +11,8 @@ def abstractmethod(funcobj):
     class that has a metaclass derived from ABCMeta cannot be
     instantiated unless all of its abstract methods are overridden.
     The abstract methods can be called using any of the normal
-    'super' call mechanisms.
+    'super' call mechanisms.  abstractmethod() may be used to declare
+    abstract methods for properties and descriptors.
 
     Usage:
 
@@ -27,17 +28,14 @@ def abstractmethod(funcobj):
 class abstractclassmethod(classmethod):
     """A decorator indicating abstract classmethods.
 
-    Similar to abstractmethod.
+    Deprecated, use 'classmethod' with 'abstractmethod' instead:
 
-    Usage:
+        class C(ABC):
-
+            @classmethod
-        class C(metaclass=ABCMeta):
+            @abstractmethod
-            @abstractclassmethod
             def my_abstract_classmethod(cls, ...):
                 ...
 
-    'abstractclassmethod' is deprecated. Use 'classmethod' with
-    'abstractmethod' instead.
     """
 
     __isabstractmethod__ = True
@@ -50,17 +48,14 @@ class abstractclassmethod(classmethod):
 class abstractstaticmethod(staticmethod):
     """A decorator indicating abstract staticmethods.
 
-    Similar to abstractmethod.
+    Deprecated, use 'staticmethod' with 'abstractmethod' instead:
 
-    Usage:
+        class C(ABC):
-
+            @staticmethod
-        class C(metaclass=ABCMeta):
+            @abstractmethod
-            @abstractstaticmethod
             def my_abstract_staticmethod(...):
                 ...
 
-    'abstractstaticmethod' is deprecated. Use 'staticmethod' with
-    'abstractmethod' instead.
     """
 
     __isabstractmethod__ = True
@@ -73,29 +68,14 @@ class abstractstaticmethod(staticmethod):
 class abstractproperty(property):
     """A decorator indicating abstract properties.
 
-    Requires that the metaclass is ABCMeta or derived from it.  A
+    Deprecated, use 'property' with 'abstractmethod' instead:
-    class that has a metaclass derived from ABCMeta cannot be
-    instantiated unless all of its abstract properties are overridden.
-    The abstract properties can be called using any of the normal
-    'super' call mechanisms.
 
-    Usage:
+        class C(ABC):
-
+            @property
-        class C(metaclass=ABCMeta):
+            @abstractmethod
-            @abstractproperty
             def my_abstract_property(self):
                 ...
 
-    This defines a read-only property; you can also define a read-write
-    abstract property using the 'long' form of property declaration:
-
-        class C(metaclass=ABCMeta):
-            def getx(self): ...
-            def setx(self, value): ...
-            x = abstractproperty(getx, setx)
-
-    'abstractproperty' is deprecated. Use 'property' with 'abstractmethod'
-    instead.
     """
 
     __isabstractmethod__ = True

extlib/Python/Lib/aifc.py

@@ -138,7 +138,7 @@ import struct
 import builtins
 import warnings
 
-__all__ = ["Error", "open", "openfp"]
+__all__ = ["Error", "open"]
 
 class Error(Exception):
     pass
@@ -920,10 +920,6 @@ def open(f, mode=None):
     else:
         raise Error("mode must be 'r', 'rb', 'w', or 'wb'")
 
-def openfp(f, mode=None):
-    warnings.warn("aifc.openfp is deprecated since Python 3.7. "
-                  "Use aifc.open instead.", DeprecationWarning, stacklevel=2)
-    return open(f, mode=mode)
 
 if __name__ == '__main__':
     import sys

extlib/Python/Lib/antigravity.py

@@ -11,7 +11,7 @@ def geohash(latitude, longitude, datedow):
     37.857713 -122.544543
 
     '''
-    # http://xkcd.com/426/
+    # https://xkcd.com/426/
-    h = hashlib.md5(datedow).hexdigest()
+    h = hashlib.md5(datedow, usedforsecurity=False).hexdigest()
     p, q = [('%f' % float.fromhex('0.' + x)) for x in (h[:16], h[16:32])]
     print('%d%s %d%s' % (latitude, p[1:], longitude, q[1:]))

extlib/Python/Lib/argparse.py

@@ -1,4 +1,5 @@
 # Author: Steven J. Bethard <steven.bethard@gmail.com>.
+# New maintainer as of 29 August 2019:  Raymond Hettinger <raymond.hettinger@gmail.com>
 
 """Command-line parsing library
 
@@ -66,6 +67,7 @@ __all__ = [
     'ArgumentParser',
     'ArgumentError',
     'ArgumentTypeError',
+    'BooleanOptionalAction',
     'FileType',
     'HelpFormatter',
     'ArgumentDefaultsHelpFormatter',
@@ -127,7 +129,7 @@ class _AttributeHolder(object):
         return '%s(%s)' % (type_name, ', '.join(arg_strings))
 
     def _get_kwargs(self):
-        return sorted(self.__dict__.items())
+        return list(self.__dict__.items())
 
     def _get_args(self):
         return []
@@ -164,15 +166,12 @@ class HelpFormatter(object):
 
         # default setting for width
         if width is None:
-            try:
+            import shutil
-                width = int(_os.environ['COLUMNS'])
+            width = shutil.get_terminal_size().columns
-            except (KeyError, ValueError):
-                width = 80
             width -= 2
 
         self._prog = prog
         self._indent_increment = indent_increment
-        self._max_help_position = max_help_position
         self._max_help_position = min(max_help_position,
                                       max(width - 20, indent_increment * 2))
         self._width = width
@@ -265,7 +264,7 @@ class HelpFormatter(object):
                 invocations.append(get_invocation(subaction))
 
             # update the maximum item length
-            invocation_length = max([len(s) for s in invocations])
+            invocation_length = max(map(len, invocations))
             action_length = invocation_length + self._current_indent
             self._action_max_length = max(self._action_max_length,
                                           action_length)
@@ -393,6 +392,9 @@ class HelpFormatter(object):
         group_actions = set()
         inserts = {}
         for group in groups:
+            if not group._group_actions:
+                raise ValueError(f'empty group {group}')
+
             try:
                 start = actions.index(group._group_actions[0])
             except ValueError:
@@ -407,13 +409,19 @@ class HelpFormatter(object):
                             inserts[start] += ' ['
                         else:
                             inserts[start] = '['
-                        inserts[end] = ']'
+                        if end in inserts:
+                            inserts[end] += ']'
+                        else:
+                            inserts[end] = ']'
                     else:
                         if start in inserts:
                             inserts[start] += ' ('
                         else:
                             inserts[start] = '('
-                        inserts[end] = ')'
+                        if end in inserts:
+                            inserts[end] += ')'
+                        else:
+                            inserts[end] = ')'
                     for i in range(start + 1, end):
                         inserts[i] = '|'
 
@@ -450,7 +458,7 @@ class HelpFormatter(object):
                 # if the Optional doesn't take a value, format is:
                 #    -s or --long
                 if action.nargs == 0:
-                    part = '%s' % option_string
+                    part = action.format_usage()
 
                 # if the Optional takes a value, format is:
                 #    -s ARGS or --long ARGS
@@ -521,12 +529,13 @@ class HelpFormatter(object):
         parts = [action_header]
 
         # if there was help for the action, add lines of help text
-        if action.help:
+        if action.help and action.help.strip():
             help_text = self._expand_help(action)
-            help_lines = self._split_lines(help_text, help_width)
+            if help_text:
-            parts.append('%*s%s\n' % (indent_first, '', help_lines[0]))
+                help_lines = self._split_lines(help_text, help_width)
-            for line in help_lines[1:]:
+                parts.append('%*s%s\n' % (indent_first, '', help_lines[0]))
-                parts.append('%*s%s\n' % (help_position, '', line))
+                for line in help_lines[1:]:
+                    parts.append('%*s%s\n' % (help_position, '', line))
 
         # or add a newline if the description doesn't end with one
         elif not action_header.endswith('\n'):
@@ -586,7 +595,11 @@ class HelpFormatter(object):
         elif action.nargs == OPTIONAL:
             result = '[%s]' % get_metavar(1)
         elif action.nargs == ZERO_OR_MORE:
-            result = '[%s [%s ...]]' % get_metavar(2)
+            metavar = get_metavar(1)
+            if len(metavar) == 2:
+                result = '[%s [%s ...]]' % metavar
+            else:
+                result = '[%s ...]' % metavar
         elif action.nargs == ONE_OR_MORE:
             result = '%s [%s ...]' % get_metavar(2)
         elif action.nargs == REMAINDER:
@@ -596,7 +609,10 @@ class HelpFormatter(object):
         elif action.nargs == SUPPRESS:
             result = ''
         else:
-            formats = ['%s' for _ in range(action.nargs)]
+            try:
+                formats = ['%s' for _ in range(action.nargs)]
+            except TypeError:
+                raise ValueError("invalid nargs value") from None
             result = ' '.join(formats) % get_metavar(action.nargs)
         return result
 
@@ -710,11 +726,13 @@ def _get_action_name(argument):
     if argument is None:
         return None
     elif argument.option_strings:
-        return  '/'.join(argument.option_strings)
+        return '/'.join(argument.option_strings)
     elif argument.metavar not in (None, SUPPRESS):
         return argument.metavar
     elif argument.dest not in (None, SUPPRESS):
         return argument.dest
+    elif argument.choices:
+        return '{' + ','.join(argument.choices) + '}'
     else:
         return None
 
@@ -830,14 +848,58 @@ class Action(_AttributeHolder):
             'default',
             'type',
             'choices',
+            'required',
             'help',
             'metavar',
         ]
         return [(name, getattr(self, name)) for name in names]
 
+    def format_usage(self):
+        return self.option_strings[0]
+
     def __call__(self, parser, namespace, values, option_string=None):
         raise NotImplementedError(_('.__call__() not defined'))
 
+class BooleanOptionalAction(Action):
+    def __init__(self,
+                 option_strings,
+                 dest,
+                 default=None,
+                 type=None,
+                 choices=None,
+                 required=False,
+                 help=None,
+                 metavar=None):
+
+        _option_strings = []
+        for option_string in option_strings:
+            _option_strings.append(option_string)
+
+            if option_string.startswith('--'):
+                option_string = '--no-' + option_string[2:]
+                _option_strings.append(option_string)
+
+        if help is not None and default is not None and default is not SUPPRESS:
+            help += " (default: %(default)s)"
+
+        super().__init__(
+            option_strings=_option_strings,
+            dest=dest,
+            nargs=0,
+            default=default,
+            type=type,
+            choices=choices,
+            required=required,
+            help=help,
+            metavar=metavar)
+
+    def __call__(self, parser, namespace, values, option_string=None):
+        if option_string in self.option_strings:
+            setattr(namespace, self.dest, not option_string.startswith('--no-'))
+
+    def format_usage(self):
+        return ' | '.join(self.option_strings)
+
 
 class _StoreAction(Action):
 
@@ -853,7 +915,7 @@ class _StoreAction(Action):
                  help=None,
                  metavar=None):
         if nargs == 0:
-            raise ValueError('nargs for store actions must be > 0; if you '
+            raise ValueError('nargs for store actions must be != 0; if you '
                              'have nothing to store, actions such as store '
                              'true or store const may be more appropriate')
         if const is not None and nargs != OPTIONAL:
@@ -945,7 +1007,7 @@ class _AppendAction(Action):
                  help=None,
                  metavar=None):
         if nargs == 0:
-            raise ValueError('nargs for append actions must be > 0; if arg '
+            raise ValueError('nargs for append actions must be != 0; if arg '
                              'strings are not supplying the value to append, '
                              'the append const action may be more appropriate')
         if const is not None and nargs != OPTIONAL:
@@ -1157,6 +1219,12 @@ class _SubParsersAction(Action):
             vars(namespace).setdefault(_UNRECOGNIZED_ARGS_ATTR, [])
             getattr(namespace, _UNRECOGNIZED_ARGS_ATTR).extend(arg_strings)
 
+class _ExtendAction(_AppendAction):
+    def __call__(self, parser, namespace, values, option_string=None):
+        items = getattr(namespace, self.dest, None)
+        items = _copy_items(items)
+        items.extend(values)
+        setattr(namespace, self.dest, items)
 
 # ==============
 # Type classes
@@ -1189,9 +1257,9 @@ class FileType(object):
         # the special argument "-" means sys.std{in,out}
         if string == '-':
             if 'r' in self._mode:
-                return _sys.stdin
+                return _sys.stdin.buffer if 'b' in self._mode else _sys.stdin
-            elif 'w' in self._mode:
+            elif any(c in self._mode for c in 'wax'):
-                return _sys.stdout
+                return _sys.stdout.buffer if 'b' in self._mode else _sys.stdout
             else:
                 msg = _('argument "-" with mode %r') % self._mode
                 raise ValueError(msg)
@@ -1201,8 +1269,9 @@ class FileType(object):
             return open(string, self._mode, self._bufsize, self._encoding,
                         self._errors)
         except OSError as e:
-            message = _("can't open '%s': %s")
+            args = {'filename': string, 'error': e}
-            raise ArgumentTypeError(message % (string, e))
+            message = _("can't open '%(filename)s': %(error)s")
+            raise ArgumentTypeError(message % args)
 
     def __repr__(self):
         args = self._mode, self._bufsize
@@ -1265,6 +1334,7 @@ class _ActionsContainer(object):
         self.register('action', 'help', _HelpAction)
         self.register('action', 'version', _VersionAction)
         self.register('action', 'parsers', _SubParsersAction)
+        self.register('action', 'extend', _ExtendAction)
 
         # raise an exception if the conflict handler is invalid
         self._get_handler()
@@ -1357,6 +1427,10 @@ class _ActionsContainer(object):
         if not callable(type_func):
             raise ValueError('%r is not callable' % (type_func,))
 
+        if type_func is FileType:
+            raise ValueError('%r is a FileType class object, instance of it'
+                             ' must be passed' % (type_func,))
+
         # raise an error if the metavar does not match the type
         if hasattr(self, "_get_formatter"):
             try:
@@ -1471,10 +1545,8 @@ class _ActionsContainer(object):
 
             # strings starting with two prefix characters are long options
             option_strings.append(option_string)
-            if option_string[0] in self.prefix_chars:
+            if len(option_string) > 1 and option_string[1] in self.prefix_chars:
-                if len(option_string) > 1:
+                long_option_strings.append(option_string)
-                    if option_string[1] in self.prefix_chars:
-                        long_option_strings.append(option_string)
 
         # infer destination, '--foo-bar' -> 'foo_bar' and '-x' -> 'x'
         dest = kwargs.pop('dest', None)
@@ -1614,6 +1686,8 @@ class ArgumentParser(_AttributeHolder, _ActionsContainer):
         - conflict_handler -- String indicating how to handle conflicts
         - add_help -- Add a -h/-help option
         - allow_abbrev -- Allow long options to be abbreviated unambiguously
+        - exit_on_error -- Determines whether or not ArgumentParser exits with
+            error info when an error occurs
     """
 
     def __init__(self,
@@ -1628,7 +1702,8 @@ class ArgumentParser(_AttributeHolder, _ActionsContainer):
                  argument_default=None,
                  conflict_handler='error',
                  add_help=True,
-                 allow_abbrev=True):
+                 allow_abbrev=True,
+                 exit_on_error=True):
 
         superinit = super(ArgumentParser, self).__init__
         superinit(description=description,
@@ -1647,6 +1722,7 @@ class ArgumentParser(_AttributeHolder, _ActionsContainer):
         self.fromfile_prefix_chars = fromfile_prefix_chars
         self.add_help = add_help
         self.allow_abbrev = allow_abbrev
+        self.exit_on_error = exit_on_error
 
         add_group = self.add_argument_group
         self._positionals = add_group(_('positional arguments'))
@@ -1777,15 +1853,19 @@ class ArgumentParser(_AttributeHolder, _ActionsContainer):
                 setattr(namespace, dest, self._defaults[dest])
 
         # parse the arguments and exit if there are any errors
-        try:
+        if self.exit_on_error:
+            try:
+                namespace, args = self._parse_known_args(args, namespace)
+            except ArgumentError:
+                err = _sys.exc_info()[1]
+                self.error(str(err))
+        else:
             namespace, args = self._parse_known_args(args, namespace)
-            if hasattr(namespace, _UNRECOGNIZED_ARGS_ATTR):
+
-                args.extend(getattr(namespace, _UNRECOGNIZED_ARGS_ATTR))
+        if hasattr(namespace, _UNRECOGNIZED_ARGS_ATTR):
-                delattr(namespace, _UNRECOGNIZED_ARGS_ATTR)
+            args.extend(getattr(namespace, _UNRECOGNIZED_ARGS_ATTR))
-            return namespace, args
+            delattr(namespace, _UNRECOGNIZED_ARGS_ATTR)
-        except ArgumentError:
+        return namespace, args
-            err = _sys.exc_info()[1]
-            self.error(str(err))
 
     def _parse_known_args(self, arg_strings, namespace):
         # replace arg strings that are file references
@@ -2074,10 +2154,11 @@ class ArgumentParser(_AttributeHolder, _ActionsContainer):
                 OPTIONAL: _('expected at most one argument'),
                 ONE_OR_MORE: _('expected at least one argument'),
             }
-            default = ngettext('expected %s argument',
+            msg = nargs_errors.get(action.nargs)
+            if msg is None:
+                msg = ngettext('expected %s argument',
                                'expected %s arguments',
                                action.nargs) % action.nargs
-            msg = nargs_errors.get(action.nargs, default)
             raise ArgumentError(action, msg)
 
         # return the number of arguments matched
@@ -2124,24 +2205,23 @@ class ArgumentParser(_AttributeHolder, _ActionsContainer):
                 action = self._option_string_actions[option_string]
                 return action, option_string, explicit_arg
 
-        if self.allow_abbrev:
+        # search through all possible prefixes of the option string
-            # search through all possible prefixes of the option string
+        # and all actions in the parser for possible interpretations
-            # and all actions in the parser for possible interpretations
+        option_tuples = self._get_option_tuples(arg_string)
-            option_tuples = self._get_option_tuples(arg_string)
 
-            # if multiple actions match, the option string was ambiguous
+        # if multiple actions match, the option string was ambiguous
-            if len(option_tuples) > 1:
+        if len(option_tuples) > 1:
-                options = ', '.join([option_string
+            options = ', '.join([option_string
-                    for action, option_string, explicit_arg in option_tuples])
+                for action, option_string, explicit_arg in option_tuples])
-                args = {'option': arg_string, 'matches': options}
+            args = {'option': arg_string, 'matches': options}
-                msg = _('ambiguous option: %(option)s could match %(matches)s')
+            msg = _('ambiguous option: %(option)s could match %(matches)s')
-                self.error(msg % args)
+            self.error(msg % args)
 
-            # if exactly one action matched, this segmentation is good,
+        # if exactly one action matched, this segmentation is good,
-            # so return the parsed action
+        # so return the parsed action
-            elif len(option_tuples) == 1:
+        elif len(option_tuples) == 1:
-                option_tuple, = option_tuples
+            option_tuple, = option_tuples
-                return option_tuple
+            return option_tuple
 
         # if it was not found as an option, but it looks like a negative
         # number, it was meant to be positional
@@ -2165,16 +2245,17 @@ class ArgumentParser(_AttributeHolder, _ActionsContainer):
         # split at the '='
         chars = self.prefix_chars
         if option_string[0] in chars and option_string[1] in chars:
-            if '=' in option_string:
+            if self.allow_abbrev:
-                option_prefix, explicit_arg = option_string.split('=', 1)
+                if '=' in option_string:
-            else:
+                    option_prefix, explicit_arg = option_string.split('=', 1)
-                option_prefix = option_string
+                else:
-                explicit_arg = None
+                    option_prefix = option_string
-            for option_string in self._option_string_actions:
+                    explicit_arg = None
-                if option_string.startswith(option_prefix):
+                for option_string in self._option_string_actions:
-                    action = self._option_string_actions[option_string]
+                    if option_string.startswith(option_prefix):
-                    tup = action, option_string, explicit_arg
+                        action = self._option_string_actions[option_string]
-                    result.append(tup)
+                        tup = action, option_string, explicit_arg
+                        result.append(tup)
 
         # single character options can be concatenated with their arguments
         # but multiple character options always have to have their argument

extlib/Python/Lib/asynchat.py

@@ -117,7 +117,7 @@ class async_chat(asyncore.dispatcher):
             data = self.recv(self.ac_in_buffer_size)
         except BlockingIOError:
             return
-        except OSError as why:
+        except OSError:
             self.handle_error()
             return
 

extlib/Python/Lib/asyncio/__init__.py

@@ -8,6 +8,7 @@ import sys
 from .base_events import *
 from .coroutines import *
 from .events import *
+from .exceptions import *
 from .futures import *
 from .locks import *
 from .protocols import *
@@ -16,6 +17,7 @@ from .queues import *
 from .streams import *
 from .subprocess import *
 from .tasks import *
+from .threads import *
 from .transports import *
 
 # Exposed for _asynciomodule.c to implement now deprecated
@@ -25,6 +27,7 @@ from .tasks import _all_tasks_compat  # NoQA
 __all__ = (base_events.__all__ +
            coroutines.__all__ +
            events.__all__ +
+           exceptions.__all__ +
            futures.__all__ +
            locks.__all__ +
            protocols.__all__ +
@@ -33,6 +36,7 @@ __all__ = (base_events.__all__ +
            streams.__all__ +
            subprocess.__all__ +
            tasks.__all__ +
+           threads.__all__ +
            transports.__all__)
 
 if sys.platform == 'win32':  # pragma: no cover

extlib/Python/Lib/asyncio/base_events.py

@@ -16,11 +16,12 @@ to modify the meaning of the API call itself.
 import collections
 import collections.abc
 import concurrent.futures
+import functools
 import heapq
 import itertools
-import logging
 import os
 import socket
+import stat
 import subprocess
 import threading
 import time
@@ -37,15 +38,18 @@ except ImportError:  # pragma: no cover
 from . import constants
 from . import coroutines
 from . import events
+from . import exceptions
 from . import futures
 from . import protocols
 from . import sslproto
+from . import staggered
 from . import tasks
 from . import transports
+from . import trsock
 from .log import logger
 
 
-__all__ = 'BaseEventLoop',
+__all__ = 'BaseEventLoop','Server',
 
 
 # Minimum number of _scheduled timer handles before cleanup of
@@ -56,10 +60,15 @@ _MIN_SCHEDULED_TIMER_HANDLES = 100
 # before cleanup of cancelled handles is performed.
 _MIN_CANCELLED_TIMER_HANDLES_FRACTION = 0.5
 
-# Exceptions which must not call the exception handler in fatal error
+
-# methods (_fatal_error())
+_HAS_IPv6 = hasattr(socket, 'AF_INET6')
-_FATAL_ERROR_IGNORE = (BrokenPipeError,
+
-                       ConnectionResetError, ConnectionAbortedError)
+# Maximum timeout passed to select to avoid OS limitations
+MAXIMUM_SELECT_TIMEOUT = 24 * 3600
+
+# Used for deprecation and removal of `loop.create_datagram_endpoint()`'s
+# *reuse_address* parameter
+_unset = object()
 
 
 def _format_handle(handle):
@@ -91,7 +100,7 @@ def _set_reuseport(sock):
                              'SO_REUSEPORT defined but not implemented.')
 
 
-def _ipaddr_info(host, port, family, type, proto):
+def _ipaddr_info(host, port, family, type, proto, flowinfo=0, scopeid=0):
     # Try to skip getaddrinfo if "host" is already an IP. Users might have
     # handled name resolution in their own code and pass in resolved IPs.
     if not hasattr(socket, 'inet_pton'):
@@ -123,7 +132,7 @@ def _ipaddr_info(host, port, family, type, proto):
 
     if family == socket.AF_UNSPEC:
         afs = [socket.AF_INET]
-        if hasattr(socket, 'AF_INET6'):
+        if _HAS_IPv6:
             afs.append(socket.AF_INET6)
     else:
         afs = [family]
@@ -139,7 +148,10 @@ def _ipaddr_info(host, port, family, type, proto):
         try:
             socket.inet_pton(af, host)
             # The host has already been resolved.
-            return af, type, proto, '', (host, port)
+            if _HAS_IPv6 and af == socket.AF_INET6:
+                return af, type, proto, '', (host, port, flowinfo, scopeid)
+            else:
+                return af, type, proto, '', (host, port)
         except OSError:
             pass
 
@@ -147,16 +159,54 @@ def _ipaddr_info(host, port, family, type, proto):
     return None
 
 
+def _interleave_addrinfos(addrinfos, first_address_family_count=1):
+    """Interleave list of addrinfo tuples by family."""
+    # Group addresses by family
+    addrinfos_by_family = collections.OrderedDict()
+    for addr in addrinfos:
+        family = addr[0]
+        if family not in addrinfos_by_family:
+            addrinfos_by_family[family] = []
+        addrinfos_by_family[family].append(addr)
+    addrinfos_lists = list(addrinfos_by_family.values())
+
+    reordered = []
+    if first_address_family_count > 1:
+        reordered.extend(addrinfos_lists[0][:first_address_family_count - 1])
+        del addrinfos_lists[0][:first_address_family_count - 1]
+    reordered.extend(
+        a for a in itertools.chain.from_iterable(
+            itertools.zip_longest(*addrinfos_lists)
+        ) if a is not None)
+    return reordered
+
+
 def _run_until_complete_cb(fut):
     if not fut.cancelled():
         exc = fut.exception()
-        if isinstance(exc, BaseException) and not isinstance(exc, Exception):
+        if isinstance(exc, (SystemExit, KeyboardInterrupt)):
             # Issue #22429: run_forever() already finished, no need to
             # stop it.
             return
     futures._get_loop(fut).stop()
 
 
+if hasattr(socket, 'TCP_NODELAY'):
+    def _set_nodelay(sock):
+        if (sock.family in {socket.AF_INET, socket.AF_INET6} and
+                sock.type == socket.SOCK_STREAM and
+                sock.proto == socket.IPPROTO_TCP):
+            sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
+else:
+    def _set_nodelay(sock):
+        pass
+
+
+def _check_ssl_socket(sock):
+    if ssl is not None and isinstance(sock, ssl.SSLSocket):
+        raise TypeError("Socket cannot be of type SSLSocket")
+
+
 class _SendfileFallbackProtocol(protocols.Protocol):
     def __init__(self, transp):
         if not isinstance(transp, transports._FlowControlMixin):
@@ -279,8 +329,8 @@ class Server(events.AbstractServer):
     @property
     def sockets(self):
         if self._sockets is None:
-            return []
+            return ()
-        return list(self._sockets)
+        return tuple(trsock.TransportSocket(s) for s in self._sockets)
 
     def close(self):
         sockets = self._sockets
@@ -305,7 +355,7 @@ class Server(events.AbstractServer):
         self._start_serving()
         # Skip one loop iteration so that all 'loop.add_reader'
         # go through.
-        await tasks.sleep(0, loop=self._loop)
+        await tasks.sleep(0)
 
     async def serve_forever(self):
         if self._serving_forever_fut is not None:
@@ -319,7 +369,7 @@ class Server(events.AbstractServer):
 
         try:
             await self._serving_forever_fut
-        except futures.CancelledError:
+        except exceptions.CancelledError:
             try:
                 self.close()
                 await self.wait_closed()
@@ -365,6 +415,8 @@ class BaseEventLoop(events.AbstractEventLoop):
         self._asyncgens = weakref.WeakSet()
         # Set to True when `loop.shutdown_asyncgens` is called.
         self._asyncgens_shutdown_called = False
+        # Set to True when `loop.shutdown_default_executor` is called.
+        self._executor_shutdown_called = False
 
     def __repr__(self):
         return (
@@ -376,18 +428,20 @@ class BaseEventLoop(events.AbstractEventLoop):
         """Create a Future object attached to the loop."""
         return futures.Future(loop=self)
 
-    def create_task(self, coro):
+    def create_task(self, coro, *, name=None):
         """Schedule a coroutine object.
 
         Return a task object.
         """
         self._check_closed()
         if self._task_factory is None:
-            task = tasks.Task(coro, loop=self)
+            task = tasks.Task(coro, loop=self, name=name)
             if task._source_traceback:
                 del task._source_traceback[-1]
         else:
             task = self._task_factory(self, coro)
+            tasks._set_task_name(task, name)
+
         return task
 
     def set_task_factory(self, factory):
@@ -460,13 +514,14 @@ class BaseEventLoop(events.AbstractEventLoop):
         if self._closed:
             raise RuntimeError('Event loop is closed')
 
+    def _check_default_executor(self):
+        if self._executor_shutdown_called:
+            raise RuntimeError('Executor shutdown has been called')
+
     def _asyncgen_finalizer_hook(self, agen):
         self._asyncgens.discard(agen)
         if not self.is_closed():
-            self.create_task(agen.aclose())
+            self.call_soon_threadsafe(self.create_task, agen.aclose())
-            # Wake up the loop if the finalizer was called from
-            # a different thread.
-            self._write_to_self()
 
     def _asyncgen_firstiter_hook(self, agen):
         if self._asyncgens_shutdown_called:
@@ -489,7 +544,7 @@ class BaseEventLoop(events.AbstractEventLoop):
         closing_agens = list(self._asyncgens)
         self._asyncgens.clear()
 
-        results = await tasks.gather(
+        results = await tasks._gather(
             *[ag.aclose() for ag in closing_agens],
             return_exceptions=True,
             loop=self)
@@ -503,14 +558,37 @@ class BaseEventLoop(events.AbstractEventLoop):
                     'asyncgen': agen
                 })
 
-    def run_forever(self):
+    async def shutdown_default_executor(self):
-        """Run until stop() is called."""
+        """Schedule the shutdown of the default executor."""
-        self._check_closed()
+        self._executor_shutdown_called = True
+        if self._default_executor is None:
+            return
+        future = self.create_future()
+        thread = threading.Thread(target=self._do_shutdown, args=(future,))
+        thread.start()
+        try:
+            await future
+        finally:
+            thread.join()
+
+    def _do_shutdown(self, future):
+        try:
+            self._default_executor.shutdown(wait=True)
+            self.call_soon_threadsafe(future.set_result, None)
+        except Exception as ex:
+            self.call_soon_threadsafe(future.set_exception, ex)
+
+    def _check_running(self):
         if self.is_running():
             raise RuntimeError('This event loop is already running')
         if events._get_running_loop() is not None:
             raise RuntimeError(
                 'Cannot run the event loop while another loop is running')
+
+    def run_forever(self):
+        """Run until stop() is called."""
+        self._check_closed()
+        self._check_running()
         self._set_coroutine_origin_tracking(self._debug)
         self._thread_id = threading.get_ident()
 
@@ -542,6 +620,7 @@ class BaseEventLoop(events.AbstractEventLoop):
         Return the Future's result, or raise its exception.
         """
         self._check_closed()
+        self._check_running()
 
         new_task = not futures.isfuture(future)
         future = tasks.ensure_future(future, loop=self)
@@ -592,6 +671,7 @@ class BaseEventLoop(events.AbstractEventLoop):
         self._closed = True
         self._ready.clear()
         self._scheduled.clear()
+        self._executor_shutdown_called = True
         executor = self._default_executor
         if executor is not None:
             self._default_executor = None
@@ -601,10 +681,9 @@ class BaseEventLoop(events.AbstractEventLoop):
         """Returns True if the event loop was closed."""
         return self._closed
 
-    def __del__(self):
+    def __del__(self, _warn=warnings.warn):
         if not self.is_closed():
-            warnings.warn(f"unclosed event loop {self!r}", ResourceWarning,
+            _warn(f"unclosed event loop {self!r}", ResourceWarning, source=self)
-                          source=self)
             if not self.is_running():
                 self.close()
 
@@ -729,13 +808,23 @@ class BaseEventLoop(events.AbstractEventLoop):
             self._check_callback(func, 'run_in_executor')
         if executor is None:
             executor = self._default_executor
+            # Only check when the default executor is being used
+            self._check_default_executor()
             if executor is None:
-                executor = concurrent.futures.ThreadPoolExecutor()
+                executor = concurrent.futures.ThreadPoolExecutor(
+                    thread_name_prefix='asyncio'
+                )
                 self._default_executor = executor
         return futures.wrap_future(
             executor.submit(func, *args), loop=self)
 
     def set_default_executor(self, executor):
+        if not isinstance(executor, concurrent.futures.ThreadPoolExecutor):
+            warnings.warn(
+                'Using the default executor that is not an instance of '
+                'ThreadPoolExecutor is deprecated and will be prohibited '
+                'in Python 3.9',
+                DeprecationWarning, 2)
         self._default_executor = executor
 
     def _getaddrinfo_debug(self, host, port, family, type, proto, flags):
@@ -780,11 +869,12 @@ class BaseEventLoop(events.AbstractEventLoop):
                             *, fallback=True):
         if self._debug and sock.gettimeout() != 0:
             raise ValueError("the socket must be non-blocking")
+        _check_ssl_socket(sock)
         self._check_sendfile_params(sock, file, offset, count)
         try:
             return await self._sock_sendfile_native(sock, file,
                                                     offset, count)
-        except events.SendfileNotAvailableError as exc:
+        except exceptions.SendfileNotAvailableError as exc:
             if not fallback:
                 raise
         return await self._sock_sendfile_fallback(sock, file,
@@ -793,9 +883,9 @@ class BaseEventLoop(events.AbstractEventLoop):
     async def _sock_sendfile_native(self, sock, file, offset, count):
         # NB: sendfile syscall is not supported for SSL sockets and
         # non-mmap files even if sendfile is supported by OS
-        raise events.SendfileNotAvailableError(
+        raise exceptions.SendfileNotAvailableError(
             f"syscall sendfile is not available for socket {sock!r} "
-            "and file {file!r} combination")
+            f"and file {file!r} combination")
 
     async def _sock_sendfile_fallback(self, sock, file, offset, count):
         if offset:
@@ -816,7 +906,7 @@ class BaseEventLoop(events.AbstractEventLoop):
                 read = await self.run_in_executor(None, file.readinto, view)
                 if not read:
                     break  # EOF
-                await self.sock_sendall(sock, view)
+                await self.sock_sendall(sock, view[:read])
                 total_sent += read
             return total_sent
         finally:
@@ -844,12 +934,49 @@ class BaseEventLoop(events.AbstractEventLoop):
                 "offset must be a non-negative integer (got {!r})".format(
                     offset))
 
+    async def _connect_sock(self, exceptions, addr_info, local_addr_infos=None):
+        """Create, bind and connect one socket."""
+        my_exceptions = []
+        exceptions.append(my_exceptions)
+        family, type_, proto, _, address = addr_info
+        sock = None
+        try:
+            sock = socket.socket(family=family, type=type_, proto=proto)
+            sock.setblocking(False)
+            if local_addr_infos is not None:
+                for _, _, _, _, laddr in local_addr_infos:
+                    try:
+                        sock.bind(laddr)
+                        break
+                    except OSError as exc:
+                        msg = (
+                            f'error while attempting to bind on '
+                            f'address {laddr!r}: '
+                            f'{exc.strerror.lower()}'
+                        )
+                        exc = OSError(exc.errno, msg)
+                        my_exceptions.append(exc)
+                else:  # all bind attempts failed
+                    raise my_exceptions.pop()
+            await self.sock_connect(sock, address)
+            return sock
+        except OSError as exc:
+            my_exceptions.append(exc)
+            if sock is not None:
+                sock.close()
+            raise
+        except:
+            if sock is not None:
+                sock.close()
+            raise
+
     async def create_connection(
             self, protocol_factory, host=None, port=None,
             *, ssl=None, family=0,
             proto=0, flags=0, sock=None,
             local_addr=None, server_hostname=None,
-            ssl_handshake_timeout=None):
+            ssl_handshake_timeout=None,
+            happy_eyeballs_delay=None, interleave=None):
         """Connect to a TCP server.
 
         Create a streaming transport connection to a given Internet host and
@@ -884,6 +1011,13 @@ class BaseEventLoop(events.AbstractEventLoop):
             raise ValueError(
                 'ssl_handshake_timeout is only meaningful with ssl')
 
+        if sock is not None:
+            _check_ssl_socket(sock)
+
+        if happy_eyeballs_delay is not None and interleave is None:
+            # If using happy eyeballs, default to interleave addresses by family
+            interleave = 1
+
         if host is not None or port is not None:
             if sock is not None:
                 raise ValueError(
@@ -902,43 +1036,31 @@ class BaseEventLoop(events.AbstractEventLoop):
                     flags=flags, loop=self)
                 if not laddr_infos:
                     raise OSError('getaddrinfo() returned empty list')
+            else:
+                laddr_infos = None
+
+            if interleave:
+                infos = _interleave_addrinfos(infos, interleave)
 
             exceptions = []
-            for family, type, proto, cname, address in infos:
+            if happy_eyeballs_delay is None:
-                try:
+                # not using happy eyeballs
-                    sock = socket.socket(family=family, type=type, proto=proto)
+                for addrinfo in infos:
-                    sock.setblocking(False)
+                    try:
-                    if local_addr is not None:
+                        sock = await self._connect_sock(
-                        for _, _, _, _, laddr in laddr_infos:
+                            exceptions, addrinfo, laddr_infos)
-                            try:
+                        break
-                                sock.bind(laddr)
+                    except OSError:
-                                break
+                        continue
-                            except OSError as exc:
+            else:  # using happy eyeballs
-                                msg = (
+                sock, _, _ = await staggered.staggered_race(
-                                    f'error while attempting to bind on '
+                    (functools.partial(self._connect_sock,
-                                    f'address {laddr!r}: '
+                                       exceptions, addrinfo, laddr_infos)
-                                    f'{exc.strerror.lower()}'
+                     for addrinfo in infos),
-                                )
+                    happy_eyeballs_delay, loop=self)
-                                exc = OSError(exc.errno, msg)
+
-                                exceptions.append(exc)
+            if sock is None:
-                        else:
+                exceptions = [exc for sub in exceptions for exc in sub]
-                            sock.close()
-                            sock = None
-                            continue
-                    if self._debug:
-                        logger.debug("connect %r to %r", sock, address)
-                    await self.sock_connect(sock, address)
-                except OSError as exc:
-                    if sock is not None:
-                        sock.close()
-                    exceptions.append(exc)
-                except:
-                    if sock is not None:
-                        sock.close()
-                    raise
-                else:
-                    break
-            else:
                 if len(exceptions) == 1:
                     raise exceptions[0]
                 else:
@@ -1037,7 +1159,7 @@ class BaseEventLoop(events.AbstractEventLoop):
             try:
                 return await self._sendfile_native(transport, file,
                                                    offset, count)
-            except events.SendfileNotAvailableError as exc:
+            except exceptions.SendfileNotAvailableError as exc:
                 if not fallback:
                     raise
 
@@ -1050,7 +1172,7 @@ class BaseEventLoop(events.AbstractEventLoop):
                                              offset, count)
 
     async def _sendfile_native(self, transp, file, offset, count):
-        raise events.SendfileNotAvailableError(
+        raise exceptions.SendfileNotAvailableError(
             "sendfile syscall is not supported")
 
     async def _sendfile_fallback(self, transp, file, offset, count):
@@ -1067,11 +1189,11 @@ class BaseEventLoop(events.AbstractEventLoop):
                     if blocksize <= 0:
                         return total_sent
                 view = memoryview(buf)[:blocksize]
-                read = file.readinto(view)
+                read = await self.run_in_executor(None, file.readinto, view)
                 if not read:
                     return total_sent  # EOF
                 await proto.drain()
-                transp.write(view)
+                transp.write(view[:read])
                 total_sent += read
         finally:
             if total_sent > 0 and hasattr(file, 'seek'):
@@ -1116,7 +1238,7 @@ class BaseEventLoop(events.AbstractEventLoop):
 
         try:
             await waiter
-        except Exception:
+        except BaseException:
             transport.close()
             conmade_cb.cancel()
             resume_cb.cancel()
@@ -1127,7 +1249,7 @@ class BaseEventLoop(events.AbstractEventLoop):
     async def create_datagram_endpoint(self, protocol_factory,
                                        local_addr=None, remote_addr=None, *,
                                        family=0, proto=0, flags=0,
-                                       reuse_address=None, reuse_port=None,
+                                       reuse_address=_unset, reuse_port=None,
                                        allow_broadcast=None, sock=None):
         """Create datagram connection."""
         if sock is not None:
@@ -1136,7 +1258,7 @@ class BaseEventLoop(events.AbstractEventLoop):
                     f'A UDP Socket was expected, got {sock!r}')
             if (local_addr or remote_addr or
                     family or proto or flags or
-                    reuse_address or reuse_port or allow_broadcast):
+                    reuse_port or allow_broadcast):
                 # show the problematic kwargs in exception msg
                 opts = dict(local_addr=local_addr, remote_addr=remote_addr,
                             family=family, proto=proto, flags=flags,
@@ -1157,15 +1279,28 @@ class BaseEventLoop(events.AbstractEventLoop):
                 for addr in (local_addr, remote_addr):
                     if addr is not None and not isinstance(addr, str):
                         raise TypeError('string is expected')
+
+                if local_addr and local_addr[0] not in (0, '\x00'):
+                    try:
+                        if stat.S_ISSOCK(os.stat(local_addr).st_mode):
+                            os.remove(local_addr)
+                    except FileNotFoundError:
+                        pass
+                    except OSError as err:
+                        # Directory may have permissions only to create socket.
+                        logger.error('Unable to check or remove stale UNIX '
+                                     'socket %r: %r',
+                                     local_addr, err)
+
                 addr_pairs_info = (((family, proto),
                                     (local_addr, remote_addr)), )
             else:
                 # join address by (family, protocol)
-                addr_infos = collections.OrderedDict()
+                addr_infos = {}  # Using order preserving dict
                 for idx, addr in ((0, local_addr), (1, remote_addr)):
                     if addr is not None:
-                        assert isinstance(addr, tuple) and len(addr) == 2, (
+                        if not (isinstance(addr, tuple) and len(addr) == 2):
-                            '2-tuple is expected')
+                            raise TypeError('2-tuple is expected')
 
                         infos = await self._ensure_resolved(
                             addr, family=family, type=socket.SOCK_DGRAM,
@@ -1190,8 +1325,18 @@ class BaseEventLoop(events.AbstractEventLoop):
 
             exceptions = []
 
-            if reuse_address is None:
+            # bpo-37228
-                reuse_address = os.name == 'posix' and sys.platform != 'cygwin'
+            if reuse_address is not _unset:
+                if reuse_address:
+                    raise ValueError("Passing `reuse_address=True` is no "
+                                     "longer supported, as the usage of "
+                                     "SO_REUSEPORT in UDP poses a significant "
+                                     "security concern.")
+                else:
+                    warnings.warn("The *reuse_address* parameter has been "
+                                  "deprecated as of 3.5.10 and is scheduled "
+                                  "for removal in 3.11.", DeprecationWarning,
+                                  stacklevel=2)
 
             for ((family, proto),
                  (local_address, remote_address)) in addr_pairs_info:
@@ -1200,9 +1345,6 @@ class BaseEventLoop(events.AbstractEventLoop):
                 try:
                     sock = socket.socket(
                         family=family, type=socket.SOCK_DGRAM, proto=proto)
-                    if reuse_address:
-                        sock.setsockopt(
-                            socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
                     if reuse_port:
                         _set_reuseport(sock)
                     if allow_broadcast:
@@ -1213,7 +1355,8 @@ class BaseEventLoop(events.AbstractEventLoop):
                     if local_addr:
                         sock.bind(local_address)
                     if remote_addr:
-                        await self.sock_connect(sock, remote_address)
+                        if not allow_broadcast:
+                            await self.sock_connect(sock, remote_address)
                         r_addr = remote_address
                 except OSError as exc:
                     if sock is not None:
@@ -1254,7 +1397,7 @@ class BaseEventLoop(events.AbstractEventLoop):
                                family=0, type=socket.SOCK_STREAM,
                                proto=0, flags=0, loop):
         host, port = address[:2]
-        info = _ipaddr_info(host, port, family, type, proto)
+        info = _ipaddr_info(host, port, family, type, proto, *address[2:])
         if info is not None:
             # "host" is already a resolved IP.
             return [info]
@@ -1304,12 +1447,14 @@ class BaseEventLoop(events.AbstractEventLoop):
             raise ValueError(
                 'ssl_handshake_timeout is only meaningful with ssl')
 
+        if sock is not None:
+            _check_ssl_socket(sock)
+
         if host is not None or port is not None:
             if sock is not None:
                 raise ValueError(
                     'host/port and sock can not be specified at the same time')
 
-            AF_INET6 = getattr(socket, 'AF_INET6', 0)
             if reuse_address is None:
                 reuse_address = os.name == 'posix' and sys.platform != 'cygwin'
             sockets = []
@@ -1324,7 +1469,7 @@ class BaseEventLoop(events.AbstractEventLoop):
             fs = [self._create_server_getaddrinfo(host, port, family=family,
                                                   flags=flags)
                   for host in hosts]
-            infos = await tasks.gather(*fs, loop=self)
+            infos = await tasks._gather(*fs, loop=self)
             infos = set(itertools.chain.from_iterable(infos))
 
             completed = False
@@ -1349,7 +1494,9 @@ class BaseEventLoop(events.AbstractEventLoop):
                     # Disable IPv4/IPv6 dual stack support (enabled by
                     # default on Linux) which makes a single socket
                     # listen on both address families.
-                    if af == AF_INET6 and hasattr(socket, 'IPPROTO_IPV6'):
+                    if (_HAS_IPv6 and
+                            af == socket.AF_INET6 and
+                            hasattr(socket, 'IPPROTO_IPV6')):
                         sock.setsockopt(socket.IPPROTO_IPV6,
                                         socket.IPV6_V6ONLY,
                                         True)
@@ -1380,7 +1527,7 @@ class BaseEventLoop(events.AbstractEventLoop):
             server._start_serving()
             # Skip one loop iteration so that all 'loop.add_reader'
             # go through.
-            await tasks.sleep(0, loop=self)
+            await tasks.sleep(0)
 
         if self._debug:
             logger.info("%r is serving", server)
@@ -1405,6 +1552,9 @@ class BaseEventLoop(events.AbstractEventLoop):
             raise ValueError(
                 'ssl_handshake_timeout is only meaningful with ssl')
 
+        if sock is not None:
+            _check_ssl_socket(sock)
+
         transport, protocol = await self._create_connection_transport(
             sock, protocol_factory, ssl, '', server_side=True,
             ssl_handshake_timeout=ssl_handshake_timeout)
@@ -1466,6 +1616,7 @@ class BaseEventLoop(events.AbstractEventLoop):
                                stderr=subprocess.PIPE,
                                universal_newlines=False,
                                shell=True, bufsize=0,
+                               encoding=None, errors=None, text=None,
                                **kwargs):
         if not isinstance(cmd, (bytes, str)):
             raise ValueError("cmd must be a string")
@@ -1475,6 +1626,13 @@ class BaseEventLoop(events.AbstractEventLoop):
             raise ValueError("shell must be True")
         if bufsize != 0:
             raise ValueError("bufsize must be 0")
+        if text:
+            raise ValueError("text must be False")
+        if encoding is not None:
+            raise ValueError("encoding must be None")
+        if errors is not None:
+            raise ValueError("errors must be None")
+
         protocol = protocol_factory()
         debug_log = None
         if self._debug:
@@ -1491,19 +1649,23 @@ class BaseEventLoop(events.AbstractEventLoop):
     async def subprocess_exec(self, protocol_factory, program, *args,
                               stdin=subprocess.PIPE, stdout=subprocess.PIPE,
                               stderr=subprocess.PIPE, universal_newlines=False,
-                              shell=False, bufsize=0, **kwargs):
+                              shell=False, bufsize=0,
+                              encoding=None, errors=None, text=None,
+                              **kwargs):
         if universal_newlines:
             raise ValueError("universal_newlines must be False")
         if shell:
             raise ValueError("shell must be False")
         if bufsize != 0:
             raise ValueError("bufsize must be 0")
+        if text:
+            raise ValueError("text must be False")
+        if encoding is not None:
+            raise ValueError("encoding must be None")
+        if errors is not None:
+            raise ValueError("errors must be None")
+
         popen_args = (program,) + args
-        for arg in popen_args:
-            if not isinstance(arg, (str, bytes)):
-                raise TypeError(
-                    f"program arguments must be a bytes or text string, "
-                    f"not {type(arg).__name__}")
         protocol = protocol_factory()
         debug_log = None
         if self._debug:
@@ -1615,7 +1777,9 @@ class BaseEventLoop(events.AbstractEventLoop):
         if self._exception_handler is None:
             try:
                 self.default_exception_handler(context)
-            except Exception:
+            except (SystemExit, KeyboardInterrupt):
+                raise
+            except BaseException:
                 # Second protection layer for unexpected errors
                 # in the default implementation, as well as for subclassed
                 # event loops with overloaded "default_exception_handler".
@@ -1624,7 +1788,9 @@ class BaseEventLoop(events.AbstractEventLoop):
         else:
             try:
                 self._exception_handler(self, context)
-            except Exception as exc:
+            except (SystemExit, KeyboardInterrupt):
+                raise
+            except BaseException as exc:
                 # Exception in the user set custom exception handler.
                 try:
                     # Let's try default handler.
@@ -1633,7 +1799,9 @@ class BaseEventLoop(events.AbstractEventLoop):
                         'exception': exc,
                         'context': context,
                     })
-                except Exception:
+                except (SystemExit, KeyboardInterrupt):
+                    raise
+                except BaseException:
                     # Guard 'default_exception_handler' in case it is
                     # overloaded.
                     logger.error('Exception in default exception handler '
@@ -1696,30 +1864,9 @@ class BaseEventLoop(events.AbstractEventLoop):
         elif self._scheduled:
             # Compute the desired timeout.
             when = self._scheduled[0]._when
-            timeout = max(0, when - self.time())
+            timeout = min(max(0, when - self.time()), MAXIMUM_SELECT_TIMEOUT)
 
-        if self._debug and timeout != 0:
+        event_list = self._selector.select(timeout)
-            t0 = self.time()
-            event_list = self._selector.select(timeout)
-            dt = self.time() - t0
-            if dt >= 1.0:
-                level = logging.INFO
-            else:
-                level = logging.DEBUG
-            nevent = len(event_list)
-            if timeout is None:
-                logger.log(level, 'poll took %.3f ms: %s events',
-                           dt * 1e3, nevent)
-            elif nevent:
-                logger.log(level,
-                           'poll %.3f ms took %.3f ms: %s events',
-                           timeout * 1e3, dt * 1e3, nevent)
-            elif dt >= 1.0:
-                logger.log(level,
-                           'poll %.3f ms took %.3f ms: timeout',
-                           timeout * 1e3, dt * 1e3)
-        else:
-            event_list = self._selector.select(timeout)
         self._process_events(event_list)
 
         # Handle 'later' callbacks that are ready.

extlib/Python/Lib/asyncio/base_futures.py

@@ -1,19 +1,10 @@
 __all__ = ()
 
-import concurrent.futures._base
 import reprlib
+from _thread import get_ident
 
 from . import format_helpers
 
-Error = concurrent.futures._base.Error
-CancelledError = concurrent.futures.CancelledError
-TimeoutError = concurrent.futures.TimeoutError
-
-
-class InvalidStateError(Error):
-    """The operation is not allowed in this state."""
-
-
 # States for Future.
 _PENDING = 'PENDING'
 _CANCELLED = 'CANCELLED'
@@ -51,6 +42,16 @@ def _format_callbacks(cb):
     return f'cb=[{cb}]'
 
 
+# bpo-42183: _repr_running is needed for repr protection
+# when a Future or Task result contains itself directly or indirectly.
+# The logic is borrowed from @reprlib.recursive_repr decorator.
+# Unfortunately, the direct decorator usage is impossible because of
+# AttributeError: '_asyncio.Task' object has no attribute '__module__' error.
+#
+# After fixing this thing we can return to the decorator based approach.
+_repr_running = set()
+
+
 def _future_repr_info(future):
     # (Future) -> str
     """helper function for Future.__repr__"""
@@ -59,9 +60,17 @@ def _future_repr_info(future):
         if future._exception is not None:
             info.append(f'exception={future._exception!r}')
         else:
-            # use reprlib to limit the length of the output, especially
+            key = id(future), get_ident()
-            # for very long strings
+            if key in _repr_running:
-            result = reprlib.repr(future._result)
+                result = '...'
+            else:
+                _repr_running.add(key)
+                try:
+                    # use reprlib to limit the length of the output, especially
+                    # for very long strings
+                    result = reprlib.repr(future._result)
+                finally:
+                    _repr_running.discard(key)
             info.append(f'result={result}')
     if future._callbacks:
         info.append(_format_callbacks(future._callbacks))

extlib/Python/Lib/asyncio/base_subprocess.py

@@ -120,10 +120,9 @@ class BaseSubprocessTransport(transports.SubprocessTransport):
 
             # Don't clear the _proc reference yet: _post_init() may still run
 
-    def __del__(self):
+    def __del__(self, _warn=warnings.warn):
         if not self._closed:
-            warnings.warn(f"unclosed transport {self!r}", ResourceWarning,
+            _warn(f"unclosed transport {self!r}", ResourceWarning, source=self)
-                          source=self)
             self.close()
 
     def get_pid(self):
@@ -183,7 +182,9 @@ class BaseSubprocessTransport(transports.SubprocessTransport):
             for callback, data in self._pending_calls:
                 loop.call_soon(callback, *data)
             self._pending_calls = None
-        except Exception as exc:
+        except (SystemExit, KeyboardInterrupt):
+            raise
+        except BaseException as exc:
             if waiter is not None and not waiter.cancelled():
                 waiter.set_exception(exc)
         else:

extlib/Python/Lib/asyncio/base_tasks.py

@@ -12,21 +12,30 @@ def _task_repr_info(task):
         # replace status
         info[0] = 'cancelling'
 
+    info.insert(1, 'name=%r' % task.get_name())
+
     coro = coroutines._format_coroutine(task._coro)
-    info.insert(1, f'coro=<{coro}>')
+    info.insert(2, f'coro=<{coro}>')
 
     if task._fut_waiter is not None:
-        info.insert(2, f'wait_for={task._fut_waiter!r}')
+        info.insert(3, f'wait_for={task._fut_waiter!r}')
     return info
 
 
 def _task_get_stack(task, limit):
     frames = []
-    try:
+    if hasattr(task._coro, 'cr_frame'):
-        # 'async def' coroutines
+        # case 1: 'async def' coroutines
         f = task._coro.cr_frame
-    except AttributeError:
+    elif hasattr(task._coro, 'gi_frame'):
+        # case 2: legacy coroutines
         f = task._coro.gi_frame
+    elif hasattr(task._coro, 'ag_frame'):
+        # case 3: async generators
+        f = task._coro.ag_frame
+    else:
+        # case 4: unknown objects
+        f = None
     if f is not None:
         while f is not None:
             if limit is not None:

extlib/Python/Lib/asyncio/coroutines.py

@@ -7,6 +7,7 @@ import os
 import sys
 import traceback
 import types
+import warnings
 
 from . import base_futures
 from . import constants
@@ -107,6 +108,9 @@ def coroutine(func):
     If the coroutine is not yielded from before it is destroyed,
     an error message is logged.
     """
+    warnings.warn('"@coroutine" decorator is deprecated since Python 3.8, use "async def" instead',
+                  DeprecationWarning,
+                  stacklevel=2)
     if inspect.iscoroutinefunction(func):
         # In Python 3.5 that's all we need to do for coroutines
         # defined with "async def".

extlib/Python/Lib/asyncio/events.py

@@ -3,7 +3,7 @@
 __all__ = (
     'AbstractEventLoopPolicy',
     'AbstractEventLoop', 'AbstractServer',
-    'Handle', 'TimerHandle', 'SendfileNotAvailableError',
+    'Handle', 'TimerHandle',
     'get_event_loop_policy', 'set_event_loop_policy',
     'get_event_loop', 'set_event_loop', 'new_event_loop',
     'get_child_watcher', 'set_child_watcher',
@@ -21,14 +21,6 @@ import threading
 from . import format_helpers
 
 
-class SendfileNotAvailableError(RuntimeError):
-    """Sendfile syscall is not available.
-
-    Raised if OS does not support sendfile syscall for given socket or
-    file type.
-    """
-
-
 class Handle:
     """Object returned by callback registration methods."""
 
@@ -86,7 +78,9 @@ class Handle:
     def _run(self):
         try:
             self._context.run(self._callback, *self._args)
-        except Exception as exc:
+        except (SystemExit, KeyboardInterrupt):
+            raise
+        except BaseException as exc:
             cb = format_helpers._format_callback_source(
                 self._callback, self._args)
             msg = f'Exception in callback {cb}'
@@ -124,20 +118,24 @@ class TimerHandle(Handle):
         return hash(self._when)
 
     def __lt__(self, other):
-        return self._when < other._when
+        if isinstance(other, TimerHandle):
+            return self._when < other._when
+        return NotImplemented
 
     def __le__(self, other):
-        if self._when < other._when:
+        if isinstance(other, TimerHandle):
-            return True
+            return self._when < other._when or self.__eq__(other)
-        return self.__eq__(other)
+        return NotImplemented
 
     def __gt__(self, other):
-        return self._when > other._when
+        if isinstance(other, TimerHandle):
+            return self._when > other._when
+        return NotImplemented
 
     def __ge__(self, other):
-        if self._when > other._when:
+        if isinstance(other, TimerHandle):
-            return True
+            return self._when > other._when or self.__eq__(other)
-        return self.__eq__(other)
+        return NotImplemented
 
     def __eq__(self, other):
         if isinstance(other, TimerHandle):
@@ -147,10 +145,6 @@ class TimerHandle(Handle):
                     self._cancelled == other._cancelled)
         return NotImplemented
 
-    def __ne__(self, other):
-        equal = self.__eq__(other)
-        return NotImplemented if equal is NotImplemented else not equal
-
     def cancel(self):
         if not self._cancelled:
             self._loop._timer_handle_cancelled(self)
@@ -254,19 +248,23 @@ class AbstractEventLoop:
         """Shutdown all active asynchronous generators."""
         raise NotImplementedError
 
+    async def shutdown_default_executor(self):
+        """Schedule the shutdown of the default executor."""
+        raise NotImplementedError
+
     # Methods scheduling callbacks.  All these return Handles.
 
     def _timer_handle_cancelled(self, handle):
         """Notification that a TimerHandle has been cancelled."""
         raise NotImplementedError
 
-    def call_soon(self, callback, *args):
+    def call_soon(self, callback, *args, context=None):
-        return self.call_later(0, callback, *args)
+        return self.call_later(0, callback, *args, context=context)
 
-    def call_later(self, delay, callback, *args):
+    def call_later(self, delay, callback, *args, context=None):
         raise NotImplementedError
 
-    def call_at(self, when, callback, *args):
+    def call_at(self, when, callback, *args, context=None):
         raise NotImplementedError
 
     def time(self):
@@ -277,15 +275,15 @@ class AbstractEventLoop:
 
     # Method scheduling a coroutine object: create a task.
 
-    def create_task(self, coro):
+    def create_task(self, coro, *, name=None):
         raise NotImplementedError
 
     # Methods for interacting with threads.
 
-    def call_soon_threadsafe(self, callback, *args):
+    def call_soon_threadsafe(self, callback, *args, context=None):
         raise NotImplementedError
 
-    async def run_in_executor(self, executor, func, *args):
+    def run_in_executor(self, executor, func, *args):
         raise NotImplementedError
 
     def set_default_executor(self, executor):
@@ -305,7 +303,8 @@ class AbstractEventLoop:
             *, ssl=None, family=0, proto=0,
             flags=0, sock=None, local_addr=None,
             server_hostname=None,
-            ssl_handshake_timeout=None):
+            ssl_handshake_timeout=None,
+            happy_eyeballs_delay=None, interleave=None):
         raise NotImplementedError
 
     async def create_server(
@@ -397,7 +396,7 @@ class AbstractEventLoop:
         The return value is a Server object, which can be used to stop
         the service.
 
-        path is a str, representing a file systsem path to bind the
+        path is a str, representing a file system path to bind the
         server socket to.
 
         sock can optionally be specified in order to use a preexisting
@@ -466,7 +465,7 @@ class AbstractEventLoop:
         # The reason to accept file-like object instead of just file descriptor
         # is: we need to own pipe and close it at transport finishing
         # Can got complicated errors if pass f.fileno(),
-        # close fd in pipe transport then close f and vise versa.
+        # close fd in pipe transport then close f and vice versa.
         raise NotImplementedError
 
     async def connect_write_pipe(self, protocol_factory, pipe):
@@ -479,7 +478,7 @@ class AbstractEventLoop:
         # The reason to accept file-like object instead of just file descriptor
         # is: we need to own pipe and close it at transport finishing
         # Can got complicated errors if pass f.fileno(),
-        # close fd in pipe transport then close f and vise versa.
+        # close fd in pipe transport then close f and vice versa.
         raise NotImplementedError
 
     async def subprocess_shell(self, protocol_factory, cmd, *,
@@ -630,13 +629,13 @@ class BaseDefaultEventLoopPolicy(AbstractEventLoopPolicy):
         self._local = self._Local()
 
     def get_event_loop(self):
-        """Get the event loop.
+        """Get the event loop for the current context.
 
-        This may be None or an instance of EventLoop.
+        Returns an instance of EventLoop or raises an exception.
         """
         if (self._local._loop is None and
                 not self._local._set_called and
-                isinstance(threading.current_thread(), threading._MainThread)):
+                threading.current_thread() is threading.main_thread()):
             self.set_event_loop(self.new_event_loop())
 
         if self._local._loop is None:

extlib/Python/Lib/asyncio/futures.py

@@ -1,7 +1,6 @@
 """A Future class similar to the one in PEP 3148."""
 
 __all__ = (
-    'CancelledError', 'TimeoutError', 'InvalidStateError',
     'Future', 'wrap_future', 'isfuture',
 )
 
@@ -9,15 +8,14 @@ import concurrent.futures
 import contextvars
 import logging
 import sys
+from types import GenericAlias
 
 from . import base_futures
 from . import events
+from . import exceptions
 from . import format_helpers
 
 
-CancelledError = base_futures.CancelledError
-InvalidStateError = base_futures.InvalidStateError
-TimeoutError = base_futures.TimeoutError
 isfuture = base_futures.isfuture
 
 
@@ -54,6 +52,9 @@ class Future:
     _exception = None
     _loop = None
     _source_traceback = None
+    _cancel_message = None
+    # A saved CancelledError for later chaining as an exception context.
+    _cancelled_exc = None
 
     # This field is used for a dual purpose:
     # - Its presence is a marker to declare that a class implements
@@ -106,6 +107,8 @@ class Future:
             context['source_traceback'] = self._source_traceback
         self._loop.call_exception_handler(context)
 
+    __class_getitem__ = classmethod(GenericAlias)
+
     @property
     def _log_traceback(self):
         return self.__log_traceback
@@ -118,9 +121,27 @@ class Future:
 
     def get_loop(self):
         """Return the event loop the Future is bound to."""
-        return self._loop
+        loop = self._loop
+        if loop is None:
+            raise RuntimeError("Future object is not initialized.")
+        return loop
 
-    def cancel(self):
+    def _make_cancelled_error(self):
+        """Create the CancelledError to raise if the Future is cancelled.
+
+        This should only be called once when handling a cancellation since
+        it erases the saved context exception value.
+        """
+        if self._cancel_message is None:
+            exc = exceptions.CancelledError()
+        else:
+            exc = exceptions.CancelledError(self._cancel_message)
+        exc.__context__ = self._cancelled_exc
+        # Remove the reference since we don't need this anymore.
+        self._cancelled_exc = None
+        return exc
+
+    def cancel(self, msg=None):
         """Cancel the future and schedule callbacks.
 
         If the future is already done or cancelled, return False.  Otherwise,
@@ -131,6 +152,7 @@ class Future:
         if self._state != _PENDING:
             return False
         self._state = _CANCELLED
+        self._cancel_message = msg
         self.__schedule_callbacks()
         return True
 
@@ -170,9 +192,10 @@ class Future:
         the future is done and has an exception set, this exception is raised.
         """
         if self._state == _CANCELLED:
-            raise CancelledError
+            exc = self._make_cancelled_error()
+            raise exc
         if self._state != _FINISHED:
-            raise InvalidStateError('Result is not ready.')
+            raise exceptions.InvalidStateError('Result is not ready.')
         self.__log_traceback = False
         if self._exception is not None:
             raise self._exception
@@ -187,9 +210,10 @@ class Future:
         InvalidStateError.
         """
         if self._state == _CANCELLED:
-            raise CancelledError
+            exc = self._make_cancelled_error()
+            raise exc
         if self._state != _FINISHED:
-            raise InvalidStateError('Exception is not set.')
+            raise exceptions.InvalidStateError('Exception is not set.')
         self.__log_traceback = False
         return self._exception
 
@@ -231,7 +255,7 @@ class Future:
         InvalidStateError.
         """
         if self._state != _PENDING:
-            raise InvalidStateError('{}: {!r}'.format(self._state, self))
+            raise exceptions.InvalidStateError(f'{self._state}: {self!r}')
         self._result = result
         self._state = _FINISHED
         self.__schedule_callbacks()
@@ -243,7 +267,7 @@ class Future:
         InvalidStateError.
         """
         if self._state != _PENDING:
-            raise InvalidStateError('{}: {!r}'.format(self._state, self))
+            raise exceptions.InvalidStateError(f'{self._state}: {self!r}')
         if isinstance(exception, type):
             exception = exception()
         if type(exception) is StopIteration:
@@ -288,6 +312,18 @@ def _set_result_unless_cancelled(fut, result):
     fut.set_result(result)
 
 
+def _convert_future_exc(exc):
+    exc_class = type(exc)
+    if exc_class is concurrent.futures.CancelledError:
+        return exceptions.CancelledError(*exc.args)
+    elif exc_class is concurrent.futures.TimeoutError:
+        return exceptions.TimeoutError(*exc.args)
+    elif exc_class is concurrent.futures.InvalidStateError:
+        return exceptions.InvalidStateError(*exc.args)
+    else:
+        return exc
+
+
 def _set_concurrent_future_state(concurrent, source):
     """Copy state from a future to a concurrent.futures.Future."""
     assert source.done()
@@ -297,7 +333,7 @@ def _set_concurrent_future_state(concurrent, source):
         return
     exception = source.exception()
     if exception is not None:
-        concurrent.set_exception(exception)
+        concurrent.set_exception(_convert_future_exc(exception))
     else:
         result = source.result()
         concurrent.set_result(result)
@@ -317,7 +353,7 @@ def _copy_future_state(source, dest):
     else:
         exception = source.exception()
         if exception is not None:
-            dest.set_exception(exception)
+            dest.set_exception(_convert_future_exc(exception))
         else:
             result = source.result()
             dest.set_result(result)

extlib/Python/Lib/asyncio/locks.py

@@ -6,88 +6,10 @@ import collections
 import warnings
 
 from . import events
-from . import futures
+from . import exceptions
-from .coroutines import coroutine
-
-
-class _ContextManager:
-    """Context manager.
-
-    This enables the following idiom for acquiring and releasing a
-    lock around a block:
-
-        with (yield from lock):
-            <block>
-
-    while failing loudly when accidentally using:
-
-        with lock:
-            <block>
-
-    Deprecated, use 'async with' statement:
-        async with lock:
-            <block>
-    """
-
-    def __init__(self, lock):
-        self._lock = lock
-
-    def __enter__(self):
-        # We have no use for the "as ..."  clause in the with
-        # statement for locks.
-        return None
-
-    def __exit__(self, *args):
-        try:
-            self._lock.release()
-        finally:
-            self._lock = None  # Crudely prevent reuse.
 
 
 class _ContextManagerMixin:
-    def __enter__(self):
-        raise RuntimeError(
-            '"yield from" should be used as context manager expression')
-
-    def __exit__(self, *args):
-        # This must exist because __enter__ exists, even though that
-        # always raises; that's how the with-statement works.
-        pass
-
-    @coroutine
-    def __iter__(self):
-        # This is not a coroutine.  It is meant to enable the idiom:
-        #
-        #     with (yield from lock):
-        #         <block>
-        #
-        # as an alternative to:
-        #
-        #     yield from lock.acquire()
-        #     try:
-        #         <block>
-        #     finally:
-        #         lock.release()
-        # Deprecated, use 'async with' statement:
-        #     async with lock:
-        #         <block>
-        warnings.warn("'with (yield from lock)' is deprecated "
-                      "use 'async with lock' instead",
-                      DeprecationWarning, stacklevel=2)
-        yield from self.acquire()
-        return _ContextManager(self)
-
-    async def __acquire_ctx(self):
-        await self.acquire()
-        return _ContextManager(self)
-
-    def __await__(self):
-        warnings.warn("'with await lock' is deprecated "
-                      "use 'async with lock' instead",
-                      DeprecationWarning, stacklevel=2)
-        # To make "with await lock" work.
-        return self.__acquire_ctx().__await__()
-
     async def __aenter__(self):
         await self.acquire()
         # We have no use for the "as ..."  clause in the with
@@ -153,12 +75,15 @@ class Lock(_ContextManagerMixin):
     """
 
     def __init__(self, *, loop=None):
-        self._waiters = collections.deque()
+        self._waiters = None
         self._locked = False
-        if loop is not None:
+        if loop is None:
-            self._loop = loop
-        else:
             self._loop = events.get_event_loop()
+        else:
+            self._loop = loop
+            warnings.warn("The loop argument is deprecated since Python 3.8, "
+                          "and scheduled for removal in Python 3.10.",
+                          DeprecationWarning, stacklevel=2)
 
     def __repr__(self):
         res = super().__repr__()
@@ -177,10 +102,13 @@ class Lock(_ContextManagerMixin):
         This method blocks until the lock is unlocked, then sets it to
         locked and returns True.
         """
-        if not self._locked and all(w.cancelled() for w in self._waiters):
+        if (not self._locked and (self._waiters is None or
+                all(w.cancelled() for w in self._waiters))):
             self._locked = True
             return True
 
+        if self._waiters is None:
+            self._waiters = collections.deque()
         fut = self._loop.create_future()
         self._waiters.append(fut)
 
@@ -192,7 +120,7 @@ class Lock(_ContextManagerMixin):
                 await fut
             finally:
                 self._waiters.remove(fut)
-        except futures.CancelledError:
+        except exceptions.CancelledError:
             if not self._locked:
                 self._wake_up_first()
             raise
@@ -219,6 +147,8 @@ class Lock(_ContextManagerMixin):
 
     def _wake_up_first(self):
         """Wake up the first waiter if it isn't done."""
+        if not self._waiters:
+            return
         try:
             fut = next(iter(self._waiters))
         except StopIteration:
@@ -243,10 +173,13 @@ class Event:
     def __init__(self, *, loop=None):
         self._waiters = collections.deque()
         self._value = False
-        if loop is not None:
+        if loop is None:
-            self._loop = loop
-        else:
             self._loop = events.get_event_loop()
+        else:
+            self._loop = loop
+            warnings.warn("The loop argument is deprecated since Python 3.8, "
+                          "and scheduled for removal in Python 3.10.",
+                          DeprecationWarning, stacklevel=2)
 
     def __repr__(self):
         res = super().__repr__()
@@ -307,13 +240,16 @@ class Condition(_ContextManagerMixin):
     """
 
     def __init__(self, lock=None, *, loop=None):
-        if loop is not None:
+        if loop is None:
-            self._loop = loop
-        else:
             self._loop = events.get_event_loop()
+        else:
+            self._loop = loop
+            warnings.warn("The loop argument is deprecated since Python 3.8, "
+                          "and scheduled for removal in Python 3.10.",
+                          DeprecationWarning, stacklevel=2)
 
         if lock is None:
-            lock = Lock(loop=self._loop)
+            lock = Lock(loop=loop)
         elif lock._loop is not self._loop:
             raise ValueError("loop argument must agree with lock")
 
@@ -363,11 +299,11 @@ class Condition(_ContextManagerMixin):
                 try:
                     await self.acquire()
                     break
-                except futures.CancelledError:
+                except exceptions.CancelledError:
                     cancelled = True
 
             if cancelled:
-                raise futures.CancelledError
+                raise exceptions.CancelledError
 
     async def wait_for(self, predicate):
         """Wait until a predicate becomes true.
@@ -435,10 +371,14 @@ class Semaphore(_ContextManagerMixin):
             raise ValueError("Semaphore initial value must be >= 0")
         self._value = value
         self._waiters = collections.deque()
-        if loop is not None:
+        if loop is None:
-            self._loop = loop
-        else:
             self._loop = events.get_event_loop()
+        else:
+            self._loop = loop
+            warnings.warn("The loop argument is deprecated since Python 3.8, "
+                          "and scheduled for removal in Python 3.10.",
+                          DeprecationWarning, stacklevel=2)
+        self._wakeup_scheduled = False
 
     def __repr__(self):
         res = super().__repr__()
@@ -452,6 +392,7 @@ class Semaphore(_ContextManagerMixin):
             waiter = self._waiters.popleft()
             if not waiter.done():
                 waiter.set_result(None)
+                self._wakeup_scheduled = True
                 return
 
     def locked(self):
@@ -467,16 +408,17 @@ class Semaphore(_ContextManagerMixin):
         called release() to make it larger than 0, and then return
         True.
         """
-        while self._value <= 0:
+        # _wakeup_scheduled is set if *another* task is scheduled to wakeup
+        # but its acquire() is not resumed yet
+        while self._wakeup_scheduled or self._value <= 0:
             fut = self._loop.create_future()
             self._waiters.append(fut)
             try:
                 await fut
-            except:
+                # reset _wakeup_scheduled *after* waiting for a future
-                # See the similar code in Queue.get.
+                self._wakeup_scheduled = False
-                fut.cancel()
+            except exceptions.CancelledError:
-                if self._value > 0 and not fut.cancelled():
+                self._wake_up_next()
-                    self._wake_up_next()
                 raise
         self._value -= 1
         return True
@@ -498,6 +440,11 @@ class BoundedSemaphore(Semaphore):
     """
 
     def __init__(self, value=1, *, loop=None):
+        if loop:
+            warnings.warn("The loop argument is deprecated since Python 3.8, "
+                          "and scheduled for removal in Python 3.10.",
+                          DeprecationWarning, stacklevel=2)
+
         self._bound_value = value
         super().__init__(value, loop=loop)
 

extlib/Python/Lib/asyncio/proactor_events.py

@@ -10,17 +10,39 @@ import io
 import os
 import socket
 import warnings
+import signal
+import threading
+import collections
 
 from . import base_events
 from . import constants
-from . import events
 from . import futures
+from . import exceptions
 from . import protocols
 from . import sslproto
 from . import transports
+from . import trsock
 from .log import logger
 
 
+def _set_socket_extra(transport, sock):
+    transport._extra['socket'] = trsock.TransportSocket(sock)
+
+    try:
+        transport._extra['sockname'] = sock.getsockname()
+    except socket.error:
+        if transport._loop.get_debug():
+            logger.warning(
+                "getsockname() failed on %r", sock, exc_info=True)
+
+    if 'peername' not in transport._extra:
+        try:
+            transport._extra['peername'] = sock.getpeername()
+        except socket.error:
+            # UDP sockets may not have a peer name
+            transport._extra['peername'] = None
+
+
 class _ProactorBasePipeTransport(transports._FlowControlMixin,
                                  transports.BaseTransport):
     """Base class for pipe and socket transports."""
@@ -88,15 +110,14 @@ class _ProactorBasePipeTransport(transports._FlowControlMixin,
             self._read_fut.cancel()
             self._read_fut = None
 
-    def __del__(self):
+    def __del__(self, _warn=warnings.warn):
         if self._sock is not None:
-            warnings.warn(f"unclosed transport {self!r}", ResourceWarning,
+            _warn(f"unclosed transport {self!r}", ResourceWarning, source=self)
-                          source=self)
             self.close()
 
     def _fatal_error(self, exc, message='Fatal error on pipe transport'):
         try:
-            if isinstance(exc, base_events._FATAL_ERROR_IGNORE):
+            if isinstance(exc, OSError):
                 if self._loop.get_debug():
                     logger.debug("%r: %s", self, message, exc_info=True)
             else:
@@ -110,7 +131,7 @@ class _ProactorBasePipeTransport(transports._FlowControlMixin,
             self._force_close(exc)
 
     def _force_close(self, exc):
-        if self._empty_waiter is not None:
+        if self._empty_waiter is not None and not self._empty_waiter.done():
             if exc is None:
                 self._empty_waiter.set_result(None)
             else:
@@ -137,7 +158,7 @@ class _ProactorBasePipeTransport(transports._FlowControlMixin,
             # end then it may fail with ERROR_NETNAME_DELETED if we
             # just close our end.  First calling shutdown() seems to
             # cure it, but maybe using DisconnectEx() would be better.
-            if hasattr(self._sock, 'shutdown'):
+            if hasattr(self._sock, 'shutdown') and self._sock.fileno() != -1:
                 self._sock.shutdown(socket.SHUT_RDWR)
             self._sock.close()
             self._sock = None
@@ -212,7 +233,9 @@ class _ProactorReadPipeTransport(_ProactorBasePipeTransport,
 
         try:
             keep_open = self._protocol.eof_received()
-        except Exception as exc:
+        except (SystemExit, KeyboardInterrupt):
+            raise
+        except BaseException as exc:
             self._fatal_error(
                 exc, 'Fatal error: protocol.eof_received() call failed.')
             return
@@ -235,7 +258,9 @@ class _ProactorReadPipeTransport(_ProactorBasePipeTransport,
         if isinstance(self._protocol, protocols.BufferedProtocol):
             try:
                 protocols._feed_data_to_buffered_proto(self._protocol, data)
-            except Exception as exc:
+            except (SystemExit, KeyboardInterrupt):
+                raise
+            except BaseException as exc:
                 self._fatal_error(exc,
                                   'Fatal error: protocol.buffer_updated() '
                                   'call failed.')
@@ -282,7 +307,7 @@ class _ProactorReadPipeTransport(_ProactorBasePipeTransport,
             self._force_close(exc)
         except OSError as exc:
             self._fatal_error(exc, 'Fatal read error on pipe transport')
-        except futures.CancelledError:
+        except exceptions.CancelledError:
             if not self._closing:
                 raise
         else:
@@ -343,6 +368,10 @@ class _ProactorBaseWritePipeTransport(_ProactorBasePipeTransport,
 
     def _loop_writing(self, f=None, data=None):
         try:
+            if f is not None and self._write_fut is None and self._closing:
+                # XXX most likely self._force_close() has been called, and
+                # it has set self._write_fut to None.
+                return
             assert f is self._write_fut
             self._write_fut = None
             self._pending_write = 0
@@ -421,6 +450,135 @@ class _ProactorWritePipeTransport(_ProactorBaseWritePipeTransport):
             self.close()
 
 
+class _ProactorDatagramTransport(_ProactorBasePipeTransport,
+                                 transports.DatagramTransport):
+    max_size = 256 * 1024
+    def __init__(self, loop, sock, protocol, address=None,
+                 waiter=None, extra=None):
+        self._address = address
+        self._empty_waiter = None
+        # We don't need to call _protocol.connection_made() since our base
+        # constructor does it for us.
+        super().__init__(loop, sock, protocol, waiter=waiter, extra=extra)
+
+        # The base constructor sets _buffer = None, so we set it here
+        self._buffer = collections.deque()
+        self._loop.call_soon(self._loop_reading)
+
+    def _set_extra(self, sock):
+        _set_socket_extra(self, sock)
+
+    def get_write_buffer_size(self):
+        return sum(len(data) for data, _ in self._buffer)
+
+    def abort(self):
+        self._force_close(None)
+
+    def sendto(self, data, addr=None):
+        if not isinstance(data, (bytes, bytearray, memoryview)):
+            raise TypeError('data argument must be bytes-like object (%r)',
+                            type(data))
+
+        if not data:
+            return
+
+        if self._address is not None and addr not in (None, self._address):
+            raise ValueError(
+                f'Invalid address: must be None or {self._address}')
+
+        if self._conn_lost and self._address:
+            if self._conn_lost >= constants.LOG_THRESHOLD_FOR_CONNLOST_WRITES:
+                logger.warning('socket.sendto() raised exception.')
+            self._conn_lost += 1
+            return
+
+        # Ensure that what we buffer is immutable.
+        self._buffer.append((bytes(data), addr))
+
+        if self._write_fut is None:
+            # No current write operations are active, kick one off
+            self._loop_writing()
+        # else: A write operation is already kicked off
+
+        self._maybe_pause_protocol()
+
+    def _loop_writing(self, fut=None):
+        try:
+            if self._conn_lost:
+                return
+
+            assert fut is self._write_fut
+            self._write_fut = None
+            if fut:
+                # We are in a _loop_writing() done callback, get the result
+                fut.result()
+
+            if not self._buffer or (self._conn_lost and self._address):
+                # The connection has been closed
+                if self._closing:
+                    self._loop.call_soon(self._call_connection_lost, None)
+                return
+
+            data, addr = self._buffer.popleft()
+            if self._address is not None:
+                self._write_fut = self._loop._proactor.send(self._sock,
+                                                            data)
+            else:
+                self._write_fut = self._loop._proactor.sendto(self._sock,
+                                                              data,
+                                                              addr=addr)
+        except OSError as exc:
+            self._protocol.error_received(exc)
+        except Exception as exc:
+            self._fatal_error(exc, 'Fatal write error on datagram transport')
+        else:
+            self._write_fut.add_done_callback(self._loop_writing)
+            self._maybe_resume_protocol()
+
+    def _loop_reading(self, fut=None):
+        data = None
+        try:
+            if self._conn_lost:
+                return
+
+            assert self._read_fut is fut or (self._read_fut is None and
+                                             self._closing)
+
+            self._read_fut = None
+            if fut is not None:
+                res = fut.result()
+
+                if self._closing:
+                    # since close() has been called we ignore any read data
+                    data = None
+                    return
+
+                if self._address is not None:
+                    data, addr = res, self._address
+                else:
+                    data, addr = res
+
+            if self._conn_lost:
+                return
+            if self._address is not None:
+                self._read_fut = self._loop._proactor.recv(self._sock,
+                                                           self.max_size)
+            else:
+                self._read_fut = self._loop._proactor.recvfrom(self._sock,
+                                                               self.max_size)
+        except OSError as exc:
+            self._protocol.error_received(exc)
+        except exceptions.CancelledError:
+            if not self._closing:
+                raise
+        else:
+            if self._read_fut is not None:
+                self._read_fut.add_done_callback(self._loop_reading)
+        finally:
+            if data:
+                self._protocol.datagram_received(data, addr)
+
+
 class _ProactorDuplexPipeTransport(_ProactorReadPipeTransport,
                                    _ProactorBaseWritePipeTransport,
                                    transports.Transport):
@@ -440,23 +598,13 @@ class _ProactorSocketTransport(_ProactorReadPipeTransport,
 
     _sendfile_compatible = constants._SendfileMode.TRY_NATIVE
 
+    def __init__(self, loop, sock, protocol, waiter=None,
+                 extra=None, server=None):
+        super().__init__(loop, sock, protocol, waiter, extra, server)
+        base_events._set_nodelay(sock)
+
     def _set_extra(self, sock):
-        self._extra['socket'] = sock
+        _set_socket_extra(self, sock)
-
-        try:
-            self._extra['sockname'] = sock.getsockname()
-        except (socket.error, AttributeError):
-            if self._loop.get_debug():
-                logger.warning(
-                    "getsockname() failed on %r", sock, exc_info=True)
-
-        if 'peername' not in self._extra:
-            try:
-                self._extra['peername'] = sock.getpeername()
-            except (socket.error, AttributeError):
-                if self._loop.get_debug():
-                    logger.warning("getpeername() failed on %r",
-                                   sock, exc_info=True)
 
     def can_write_eof(self):
         return True
@@ -480,6 +628,9 @@ class BaseProactorEventLoop(base_events.BaseEventLoop):
         self._accept_futures = {}   # socket file descriptor => Future
         proactor.set_loop(self)
         self._make_self_pipe()
+        if threading.current_thread() is threading.main_thread():
+            # wakeup fd can only be installed to a file descriptor from the main thread
+            signal.set_wakeup_fd(self._csock.fileno())
 
     def _make_socket_transport(self, sock, protocol, waiter=None,
                                extra=None, server=None):
@@ -499,6 +650,11 @@ class BaseProactorEventLoop(base_events.BaseEventLoop):
                                  extra=extra, server=server)
         return ssl_protocol._app_transport
 
+    def _make_datagram_transport(self, sock, protocol,
+                                 address=None, waiter=None, extra=None):
+        return _ProactorDatagramTransport(self, sock, protocol, address,
+                                          waiter, extra)
+
     def _make_duplex_pipe_transport(self, sock, protocol, waiter=None,
                                     extra=None):
         return _ProactorDuplexPipeTransport(self,
@@ -520,6 +676,8 @@ class BaseProactorEventLoop(base_events.BaseEventLoop):
         if self.is_closed():
             return
 
+        if threading.current_thread() is threading.main_thread():
+            signal.set_wakeup_fd(-1)
         # Call these methods before closing the event loop (before calling
         # BaseEventLoop.close), because they can schedule callbacks with
         # call_soon(), which is forbidden when the event loop is closed.
@@ -551,11 +709,11 @@ class BaseProactorEventLoop(base_events.BaseEventLoop):
         try:
             fileno = file.fileno()
         except (AttributeError, io.UnsupportedOperation) as err:
-            raise events.SendfileNotAvailableError("not a regular file")
+            raise exceptions.SendfileNotAvailableError("not a regular file")
         try:
             fsize = os.fstat(fileno).st_size
-        except OSError as err:
+        except OSError:
-            raise events.SendfileNotAvailableError("not a regular file")
+            raise exceptions.SendfileNotAvailableError("not a regular file")
         blocksize = count if count else fsize
         if not blocksize:
             return 0  # empty file
@@ -604,17 +762,26 @@ class BaseProactorEventLoop(base_events.BaseEventLoop):
         self._ssock.setblocking(False)
         self._csock.setblocking(False)
         self._internal_fds += 1
-        self.call_soon(self._loop_self_reading)
 
     def _loop_self_reading(self, f=None):
         try:
             if f is not None:
                 f.result()  # may raise
+            if self._self_reading_future is not f:
+                # When we scheduled this Future, we assigned it to
+                # _self_reading_future. If it's not there now, something has
+                # tried to cancel the loop while this callback was still in the
+                # queue (see windows_events.ProactorEventLoop.run_forever). In
+                # that case stop here instead of continuing to schedule a new
+                # iteration.
+                return
             f = self._proactor.recv(self._ssock, 4096)
-        except futures.CancelledError:
+        except exceptions.CancelledError:
             # _close_self_pipe() has been called, stop waiting for data
             return
-        except Exception as exc:
+        except (SystemExit, KeyboardInterrupt):
+            raise
+        except BaseException as exc:
             self.call_exception_handler({
                 'message': 'Error on reading from the event loop self pipe',
                 'exception': exc,
@@ -625,7 +792,22 @@ class BaseProactorEventLoop(base_events.BaseEventLoop):
             f.add_done_callback(self._loop_self_reading)
 
     def _write_to_self(self):
-        self._csock.send(b'\0')
+        # This may be called from a different thread, possibly after
+        # _close_self_pipe() has been called or even while it is
+        # running.  Guard for self._csock being None or closed.  When
+        # a socket is closed, send() raises OSError (with errno set to
+        # EBADF, but let's not rely on the exact error code).
+        csock = self._csock
+        if csock is None:
+            return
+
+        try:
+            csock.send(b'\0')
+        except OSError:
+            if self._debug:
+                logger.debug("Fail to write a null byte into the "
+                             "self-pipe socket",
+                             exc_info=True)
 
     def _start_serving(self, protocol_factory, sock,
                        sslcontext=None, server=None, backlog=100,
@@ -656,13 +838,13 @@ class BaseProactorEventLoop(base_events.BaseEventLoop):
                     self.call_exception_handler({
                         'message': 'Accept failed on a socket',
                         'exception': exc,
-                        'socket': sock,
+                        'socket': trsock.TransportSocket(sock),
                     })
                     sock.close()
                 elif self._debug:
                     logger.debug("Accept failed on socket %r",
                                  sock, exc_info=True)
-            except futures.CancelledError:
+            except exceptions.CancelledError:
                 sock.close()
             else:
                 self._accept_futures[sock.fileno()] = f

extlib/Python/Lib/asyncio/protocols.py

@@ -16,6 +16,8 @@ class BaseProtocol:
     write-only transport like write pipe
     """
 
+    __slots__ = ()
+
     def connection_made(self, transport):
         """Called when a connection is made.
 
@@ -87,6 +89,8 @@ class Protocol(BaseProtocol):
     * CL: connection_lost()
     """
 
+    __slots__ = ()
+
     def data_received(self, data):
         """Called when some data is received.
 
@@ -105,10 +109,6 @@ class Protocol(BaseProtocol):
 class BufferedProtocol(BaseProtocol):
     """Interface for stream protocol with manual buffer control.
 
-    Important: this has been added to asyncio in Python 3.7
-    *on a provisional basis*!  Consider it as an experimental API that
-    might be changed or removed in Python 3.8.
-
     Event methods, such as `create_server` and `create_connection`,
     accept factories that return protocols that implement this interface.
 
@@ -130,6 +130,8 @@ class BufferedProtocol(BaseProtocol):
     * CL: connection_lost()
     """
 
+    __slots__ = ()
+
     def get_buffer(self, sizehint):
         """Called to allocate a new receive buffer.
 
@@ -160,6 +162,8 @@ class BufferedProtocol(BaseProtocol):
 class DatagramProtocol(BaseProtocol):
     """Interface for datagram protocol."""
 
+    __slots__ = ()
+
     def datagram_received(self, data, addr):
         """Called when some datagram is received."""
 
@@ -173,6 +177,8 @@ class DatagramProtocol(BaseProtocol):
 class SubprocessProtocol(BaseProtocol):
     """Interface for protocol for subprocess calls."""
 
+    __slots__ = ()
+
     def pipe_data_received(self, fd, data):
         """Called when the subprocess writes data into stdout/stderr pipe.
 

extlib/Python/Lib/asyncio/queues.py

@@ -2,6 +2,8 @@ __all__ = ('Queue', 'PriorityQueue', 'LifoQueue', 'QueueFull', 'QueueEmpty')
 
 import collections
 import heapq
+import warnings
+from types import GenericAlias
 
 from . import events
 from . import locks
@@ -34,6 +36,9 @@ class Queue:
             self._loop = events.get_event_loop()
         else:
             self._loop = loop
+            warnings.warn("The loop argument is deprecated since Python 3.8, "
+                          "and scheduled for removal in Python 3.10.",
+                          DeprecationWarning, stacklevel=2)
         self._maxsize = maxsize
 
         # Futures.
@@ -41,7 +46,7 @@ class Queue:
         # Futures.
         self._putters = collections.deque()
         self._unfinished_tasks = 0
-        self._finished = locks.Event(loop=self._loop)
+        self._finished = locks.Event(loop=loop)
         self._finished.set()
         self._init(maxsize)
 
@@ -72,6 +77,8 @@ class Queue:
     def __str__(self):
         return f'<{type(self).__name__} {self._format()}>'
 
+    __class_getitem__ = classmethod(GenericAlias)
+
     def _format(self):
         result = f'maxsize={self._maxsize!r}'
         if getattr(self, '_queue', None):

extlib/Python/Lib/asyncio/runners.py

@@ -5,8 +5,8 @@ from . import events
 from . import tasks
 
 
-def run(main, *, debug=False):
+def run(main, *, debug=None):
-    """Run a coroutine.
+    """Execute the coroutine and return the result.
 
     This function runs the passed coroutine, taking care of
     managing the asyncio event loop and finalizing asynchronous
@@ -39,12 +39,14 @@ def run(main, *, debug=False):
     loop = events.new_event_loop()
     try:
         events.set_event_loop(loop)
-        loop.set_debug(debug)
+        if debug is not None:
+            loop.set_debug(debug)
         return loop.run_until_complete(main)
     finally:
         try:
             _cancel_all_tasks(loop)
             loop.run_until_complete(loop.shutdown_asyncgens())
+            loop.run_until_complete(loop.shutdown_default_executor())
         finally:
             events.set_event_loop(None)
             loop.close()
@@ -59,7 +61,7 @@ def _cancel_all_tasks(loop):
         task.cancel()
 
     loop.run_until_complete(
-        tasks.gather(*to_cancel, loop=loop, return_exceptions=True))
+        tasks._gather(*to_cancel, loop=loop, return_exceptions=True))
 
     for task in to_cancel:
         if task.cancelled():

extlib/Python/Lib/asyncio/selector_events.py

@@ -25,6 +25,7 @@ from . import futures
 from . import protocols
 from . import sslproto
 from . import transports
+from . import trsock
 from .log import logger
 
 
@@ -39,17 +40,6 @@ def _test_selector_event(selector, fd, event):
         return bool(key.events & event)
 
 
-if hasattr(socket, 'TCP_NODELAY'):
-    def _set_nodelay(sock):
-        if (sock.family in {socket.AF_INET, socket.AF_INET6} and
-                sock.type == socket.SOCK_STREAM and
-                sock.proto == socket.IPPROTO_TCP):
-            sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
-else:
-    def _set_nodelay(sock):
-        pass
-
-
 class BaseSelectorEventLoop(base_events.BaseEventLoop):
     """Selector event loop.
 
@@ -138,14 +128,16 @@ class BaseSelectorEventLoop(base_events.BaseEventLoop):
         # a socket is closed, send() raises OSError (with errno set to
         # EBADF, but let's not rely on the exact error code).
         csock = self._csock
-        if csock is not None:
+        if csock is None:
-            try:
+            return
-                csock.send(b'\0')
+
-            except OSError:
+        try:
-                if self._debug:
+            csock.send(b'\0')
-                    logger.debug("Fail to write a null byte into the "
+        except OSError:
-                                 "self-pipe socket",
+            if self._debug:
-                                 exc_info=True)
+                logger.debug("Fail to write a null byte into the "
+                             "self-pipe socket",
+                             exc_info=True)
 
     def _start_serving(self, protocol_factory, sock,
                        sslcontext=None, server=None, backlog=100,
@@ -182,7 +174,7 @@ class BaseSelectorEventLoop(base_events.BaseEventLoop):
                     self.call_exception_handler({
                         'message': 'socket.accept() out of system resource',
                         'exception': exc,
-                        'socket': sock,
+                        'socket': trsock.TransportSocket(sock),
                     })
                     self._remove_reader(sock.fileno())
                     self.call_later(constants.ACCEPT_RETRY_DELAY,
@@ -219,12 +211,14 @@ class BaseSelectorEventLoop(base_events.BaseEventLoop):
 
             try:
                 await waiter
-            except:
+            except BaseException:
                 transport.close()
                 raise
+                # It's now up to the protocol to handle the connection.
 
-            # It's now up to the protocol to handle the connection.
+        except (SystemExit, KeyboardInterrupt):
-        except Exception as exc:
+            raise
+        except BaseException as exc:
             if self._debug:
                 context = {
                     'message':
@@ -269,6 +263,7 @@ class BaseSelectorEventLoop(base_events.BaseEventLoop):
                                   (handle, writer))
             if reader is not None:
                 reader.cancel()
+        return handle
 
     def _remove_reader(self, fd):
         if self.is_closed():
@@ -305,6 +300,7 @@ class BaseSelectorEventLoop(base_events.BaseEventLoop):
                                   (reader, handle))
             if writer is not None:
                 writer.cancel()
+        return handle
 
     def _remove_writer(self, fd):
         """Remove a writer callback."""
@@ -332,7 +328,7 @@ class BaseSelectorEventLoop(base_events.BaseEventLoop):
     def add_reader(self, fd, callback, *args):
         """Add a reader callback."""
         self._ensure_fd_no_transport(fd)
-        return self._add_reader(fd, callback, *args)
+        self._add_reader(fd, callback, *args)
 
     def remove_reader(self, fd):
         """Remove a reader callback."""
@@ -342,7 +338,7 @@ class BaseSelectorEventLoop(base_events.BaseEventLoop):
     def add_writer(self, fd, callback, *args):
         """Add a writer callback.."""
         self._ensure_fd_no_transport(fd)
-        return self._add_writer(fd, callback, *args)
+        self._add_writer(fd, callback, *args)
 
     def remove_writer(self, fd):
         """Remove a writer callback."""
@@ -356,29 +352,37 @@ class BaseSelectorEventLoop(base_events.BaseEventLoop):
         The maximum amount of data to be received at once is specified by
         nbytes.
         """
+        base_events._check_ssl_socket(sock)
         if self._debug and sock.gettimeout() != 0:
             raise ValueError("the socket must be non-blocking")
+        try:
+            return sock.recv(n)
+        except (BlockingIOError, InterruptedError):
+            pass
         fut = self.create_future()
-        self._sock_recv(fut, None, sock, n)
+        fd = sock.fileno()
+        self._ensure_fd_no_transport(fd)
+        handle = self._add_reader(fd, self._sock_recv, fut, sock, n)
+        fut.add_done_callback(
+            functools.partial(self._sock_read_done, fd, handle=handle))
         return await fut
 
-    def _sock_recv(self, fut, registered_fd, sock, n):
+    def _sock_read_done(self, fd, fut, handle=None):
+        if handle is None or not handle.cancelled():
+            self.remove_reader(fd)
+
+    def _sock_recv(self, fut, sock, n):
         # _sock_recv() can add itself as an I/O callback if the operation can't
         # be done immediately. Don't use it directly, call sock_recv().
-        if registered_fd is not None:
+        if fut.done():
-            # Remove the callback early.  It should be rare that the
-            # selector says the fd is ready but the call still returns
-            # EAGAIN, and I am willing to take a hit in that case in
-            # order to simplify the common case.
-            self.remove_reader(registered_fd)
-        if fut.cancelled():
             return
         try:
             data = sock.recv(n)
         except (BlockingIOError, InterruptedError):
-            fd = sock.fileno()
+            return  # try again next time
-            self.add_reader(fd, self._sock_recv, fut, fd, sock, n)
+        except (SystemExit, KeyboardInterrupt):
-        except Exception as exc:
+            raise
+        except BaseException as exc:
             fut.set_exception(exc)
         else:
             fut.set_result(data)
@@ -389,30 +393,34 @@ class BaseSelectorEventLoop(base_events.BaseEventLoop):
         The received data is written into *buf* (a writable buffer).
         The return value is the number of bytes written.
         """
+        base_events._check_ssl_socket(sock)
         if self._debug and sock.gettimeout() != 0:
             raise ValueError("the socket must be non-blocking")
+        try:
+            return sock.recv_into(buf)
+        except (BlockingIOError, InterruptedError):
+            pass
         fut = self.create_future()
-        self._sock_recv_into(fut, None, sock, buf)
+        fd = sock.fileno()
+        self._ensure_fd_no_transport(fd)
+        handle = self._add_reader(fd, self._sock_recv_into, fut, sock, buf)
+        fut.add_done_callback(
+            functools.partial(self._sock_read_done, fd, handle=handle))
         return await fut
 
-    def _sock_recv_into(self, fut, registered_fd, sock, buf):
+    def _sock_recv_into(self, fut, sock, buf):
         # _sock_recv_into() can add itself as an I/O callback if the operation
         # can't be done immediately. Don't use it directly, call
         # sock_recv_into().
-        if registered_fd is not None:
+        if fut.done():
-            # Remove the callback early.  It should be rare that the
-            # selector says the FD is ready but the call still returns
-            # EAGAIN, and I am willing to take a hit in that case in
-            # order to simplify the common case.
-            self.remove_reader(registered_fd)
-        if fut.cancelled():
             return
         try:
             nbytes = sock.recv_into(buf)
         except (BlockingIOError, InterruptedError):
-            fd = sock.fileno()
+            return  # try again next time
-            self.add_reader(fd, self._sock_recv_into, fut, fd, sock, buf)
+        except (SystemExit, KeyboardInterrupt):
-        except Exception as exc:
+            raise
+        except BaseException as exc:
             fut.set_exception(exc)
         else:
             fut.set_result(nbytes)
@@ -426,48 +434,65 @@ class BaseSelectorEventLoop(base_events.BaseEventLoop):
         raised, and there is no way to determine how much data, if any, was
         successfully processed by the receiving end of the connection.
         """
+        base_events._check_ssl_socket(sock)
         if self._debug and sock.gettimeout() != 0:
             raise ValueError("the socket must be non-blocking")
-        fut = self.create_future()
-        if data:
-            self._sock_sendall(fut, None, sock, data)
-        else:
-            fut.set_result(None)
-        return await fut
-
-    def _sock_sendall(self, fut, registered_fd, sock, data):
-        if registered_fd is not None:
-            self.remove_writer(registered_fd)
-        if fut.cancelled():
-            return
-
         try:
             n = sock.send(data)
         except (BlockingIOError, InterruptedError):
             n = 0
-        except Exception as exc:
+
+        if n == len(data):
+            # all data sent
+            return
+
+        fut = self.create_future()
+        fd = sock.fileno()
+        self._ensure_fd_no_transport(fd)
+        # use a trick with a list in closure to store a mutable state
+        handle = self._add_writer(fd, self._sock_sendall, fut, sock,
+                                  memoryview(data), [n])
+        fut.add_done_callback(
+            functools.partial(self._sock_write_done, fd, handle=handle))
+        return await fut
+
+    def _sock_sendall(self, fut, sock, view, pos):
+        if fut.done():
+            # Future cancellation can be scheduled on previous loop iteration
+            return
+        start = pos[0]
+        try:
+            n = sock.send(view[start:])
+        except (BlockingIOError, InterruptedError):
+            return
+        except (SystemExit, KeyboardInterrupt):
+            raise
+        except BaseException as exc:
             fut.set_exception(exc)
             return
 
-        if n == len(data):
+        start += n
+
+        if start == len(view):
             fut.set_result(None)
         else:
-            if n:
+            pos[0] = start
-                data = data[n:]
-            fd = sock.fileno()
-            self.add_writer(fd, self._sock_sendall, fut, fd, sock, data)
 
     async def sock_connect(self, sock, address):
         """Connect to a remote socket at address.
 
         This method is a coroutine.
         """
+        base_events._check_ssl_socket(sock)
         if self._debug and sock.gettimeout() != 0:
             raise ValueError("the socket must be non-blocking")
 
-        if not hasattr(socket, 'AF_UNIX') or sock.family != socket.AF_UNIX:
+        if sock.family == socket.AF_INET or (
+                base_events._HAS_IPv6 and sock.family == socket.AF_INET6):
             resolved = await self._ensure_resolved(
-                address, family=sock.family, proto=sock.proto, loop=self)
+                address, family=sock.family, type=sock.type, proto=sock.proto,
+                loop=self,
+            )
             _, _, _, _, address = resolved[0]
 
         fut = self.create_future()
@@ -483,19 +508,24 @@ class BaseSelectorEventLoop(base_events.BaseEventLoop):
             # connection runs in background. We have to wait until the socket
             # becomes writable to be notified when the connection succeed or
             # fails.
+            self._ensure_fd_no_transport(fd)
+            handle = self._add_writer(
+                fd, self._sock_connect_cb, fut, sock, address)
             fut.add_done_callback(
-                functools.partial(self._sock_connect_done, fd))
+                functools.partial(self._sock_write_done, fd, handle=handle))
-            self.add_writer(fd, self._sock_connect_cb, fut, sock, address)
+        except (SystemExit, KeyboardInterrupt):
-        except Exception as exc:
+            raise
+        except BaseException as exc:
             fut.set_exception(exc)
         else:
             fut.set_result(None)
 
-    def _sock_connect_done(self, fd, fut):
+    def _sock_write_done(self, fd, fut, handle=None):
-        self.remove_writer(fd)
+        if handle is None or not handle.cancelled():
+            self.remove_writer(fd)
 
     def _sock_connect_cb(self, fut, sock, address):
-        if fut.cancelled():
+        if fut.done():
             return
 
         try:
@@ -506,7 +536,9 @@ class BaseSelectorEventLoop(base_events.BaseEventLoop):
         except (BlockingIOError, InterruptedError):
             # socket is still registered, the callback will be retried later
             pass
-        except Exception as exc:
+        except (SystemExit, KeyboardInterrupt):
+            raise
+        except BaseException as exc:
             fut.set_exception(exc)
         else:
             fut.set_result(None)
@@ -519,24 +551,26 @@ class BaseSelectorEventLoop(base_events.BaseEventLoop):
         object usable to send and receive data on the connection, and address
         is the address bound to the socket on the other end of the connection.
         """
+        base_events._check_ssl_socket(sock)
         if self._debug and sock.gettimeout() != 0:
             raise ValueError("the socket must be non-blocking")
         fut = self.create_future()
-        self._sock_accept(fut, False, sock)
+        self._sock_accept(fut, sock)
         return await fut
 
-    def _sock_accept(self, fut, registered, sock):
+    def _sock_accept(self, fut, sock):
         fd = sock.fileno()
-        if registered:
-            self.remove_reader(fd)
-        if fut.cancelled():
-            return
         try:
             conn, address = sock.accept()
             conn.setblocking(False)
         except (BlockingIOError, InterruptedError):
-            self.add_reader(fd, self._sock_accept, fut, True, sock)
+            self._ensure_fd_no_transport(fd)
-        except Exception as exc:
+            handle = self._add_reader(fd, self._sock_accept, fut, sock)
+            fut.add_done_callback(
+                functools.partial(self._sock_read_done, fd, handle=handle))
+        except (SystemExit, KeyboardInterrupt):
+            raise
+        except BaseException as exc:
             fut.set_exception(exc)
         else:
             fut.set_result((conn, address))
@@ -588,8 +622,11 @@ class _SelectorTransport(transports._FlowControlMixin,
 
     def __init__(self, loop, sock, protocol, extra=None, server=None):
         super().__init__(extra, loop)
-        self._extra['socket'] = sock
+        self._extra['socket'] = trsock.TransportSocket(sock)
-        self._extra['sockname'] = sock.getsockname()
+        try:
+            self._extra['sockname'] = sock.getsockname()
+        except OSError:
+            self._extra['sockname'] = None
         if 'peername' not in self._extra:
             try:
                 self._extra['peername'] = sock.getpeername()
@@ -660,15 +697,14 @@ class _SelectorTransport(transports._FlowControlMixin,
             self._loop._remove_writer(self._sock_fd)
             self._loop.call_soon(self._call_connection_lost, None)
 
-    def __del__(self):
+    def __del__(self, _warn=warnings.warn):
         if self._sock is not None:
-            warnings.warn(f"unclosed transport {self!r}", ResourceWarning,
+            _warn(f"unclosed transport {self!r}", ResourceWarning, source=self)
-                          source=self)
             self._sock.close()
 
     def _fatal_error(self, exc, message='Fatal error on transport'):
         # Should be called from exception handler only.
-        if isinstance(exc, base_events._FATAL_ERROR_IGNORE):
+        if isinstance(exc, OSError):
             if self._loop.get_debug():
                 logger.debug("%r: %s", self, message, exc_info=True)
         else:
@@ -733,7 +769,7 @@ class _SelectorSocketTransport(_SelectorTransport):
         # Disable the Nagle algorithm -- small writes will be
         # sent without waiting for the TCP ACK.  This generally
         # decreases the latency (in some cases significantly.)
-        _set_nodelay(self._sock)
+        base_events._set_nodelay(self._sock)
 
         self._loop.call_soon(self._protocol.connection_made, self)
         # only start reading when connection_made() has been called
@@ -782,7 +818,9 @@ class _SelectorSocketTransport(_SelectorTransport):
             buf = self._protocol.get_buffer(-1)
             if not len(buf):
                 raise RuntimeError('get_buffer() returned an empty buffer')
-        except Exception as exc:
+        except (SystemExit, KeyboardInterrupt):
+            raise
+        except BaseException as exc:
             self._fatal_error(
                 exc, 'Fatal error: protocol.get_buffer() call failed.')
             return
@@ -791,7 +829,9 @@ class _SelectorSocketTransport(_SelectorTransport):
             nbytes = self._sock.recv_into(buf)
         except (BlockingIOError, InterruptedError):
             return
-        except Exception as exc:
+        except (SystemExit, KeyboardInterrupt):
+            raise
+        except BaseException as exc:
             self._fatal_error(exc, 'Fatal read error on socket transport')
             return
 
@@ -801,7 +841,9 @@ class _SelectorSocketTransport(_SelectorTransport):
 
         try:
             self._protocol.buffer_updated(nbytes)
-        except Exception as exc:
+        except (SystemExit, KeyboardInterrupt):
+            raise
+        except BaseException as exc:
             self._fatal_error(
                 exc, 'Fatal error: protocol.buffer_updated() call failed.')
 
@@ -812,7 +854,9 @@ class _SelectorSocketTransport(_SelectorTransport):
             data = self._sock.recv(self.max_size)
         except (BlockingIOError, InterruptedError):
             return
-        except Exception as exc:
+        except (SystemExit, KeyboardInterrupt):
+            raise
+        except BaseException as exc:
             self._fatal_error(exc, 'Fatal read error on socket transport')
             return
 
@@ -822,7 +866,9 @@ class _SelectorSocketTransport(_SelectorTransport):
 
         try:
             self._protocol.data_received(data)
-        except Exception as exc:
+        except (SystemExit, KeyboardInterrupt):
+            raise
+        except BaseException as exc:
             self._fatal_error(
                 exc, 'Fatal error: protocol.data_received() call failed.')
 
@@ -832,7 +878,9 @@ class _SelectorSocketTransport(_SelectorTransport):
 
         try:
             keep_open = self._protocol.eof_received()
-        except Exception as exc:
+        except (SystemExit, KeyboardInterrupt):
+            raise
+        except BaseException as exc:
             self._fatal_error(
                 exc, 'Fatal error: protocol.eof_received() call failed.')
             return
@@ -868,7 +916,9 @@ class _SelectorSocketTransport(_SelectorTransport):
                 n = self._sock.send(data)
             except (BlockingIOError, InterruptedError):
                 pass
-            except Exception as exc:
+            except (SystemExit, KeyboardInterrupt):
+                raise
+            except BaseException as exc:
                 self._fatal_error(exc, 'Fatal write error on socket transport')
                 return
             else:
@@ -891,7 +941,9 @@ class _SelectorSocketTransport(_SelectorTransport):
             n = self._sock.send(self._buffer)
         except (BlockingIOError, InterruptedError):
             pass
-        except Exception as exc:
+        except (SystemExit, KeyboardInterrupt):
+            raise
+        except BaseException as exc:
             self._loop._remove_writer(self._sock_fd)
             self._buffer.clear()
             self._fatal_error(exc, 'Fatal write error on socket transport')
@@ -967,7 +1019,9 @@ class _SelectorDatagramTransport(_SelectorTransport):
             pass
         except OSError as exc:
             self._protocol.error_received(exc)
-        except Exception as exc:
+        except (SystemExit, KeyboardInterrupt):
+            raise
+        except BaseException as exc:
             self._fatal_error(exc, 'Fatal read error on datagram transport')
         else:
             self._protocol.datagram_received(data, addr)
@@ -979,9 +1033,11 @@ class _SelectorDatagramTransport(_SelectorTransport):
         if not data:
             return
 
-        if self._address and addr not in (None, self._address):
+        if self._address:
-            raise ValueError(
+            if addr not in (None, self._address):
-                f'Invalid address: must be None or {self._address}')
+                raise ValueError(
+                    f'Invalid address: must be None or {self._address}')
+            addr = self._address
 
         if self._conn_lost and self._address:
             if self._conn_lost >= constants.LOG_THRESHOLD_FOR_CONNLOST_WRITES:
@@ -992,7 +1048,7 @@ class _SelectorDatagramTransport(_SelectorTransport):
         if not self._buffer:
             # Attempt to send it right away first.
             try:
-                if self._address:
+                if self._extra['peername']:
                     self._sock.send(data)
                 else:
                     self._sock.sendto(data, addr)
@@ -1002,7 +1058,9 @@ class _SelectorDatagramTransport(_SelectorTransport):
             except OSError as exc:
                 self._protocol.error_received(exc)
                 return
-            except Exception as exc:
+            except (SystemExit, KeyboardInterrupt):
+                raise
+            except BaseException as exc:
                 self._fatal_error(
                     exc, 'Fatal write error on datagram transport')
                 return
@@ -1015,7 +1073,7 @@ class _SelectorDatagramTransport(_SelectorTransport):
         while self._buffer:
             data, addr = self._buffer.popleft()
             try:
-                if self._address:
+                if self._extra['peername']:
                     self._sock.send(data)
                 else:
                     self._sock.sendto(data, addr)
@@ -1025,7 +1083,9 @@ class _SelectorDatagramTransport(_SelectorTransport):
             except OSError as exc:
                 self._protocol.error_received(exc)
                 return
-            except Exception as exc:
+            except (SystemExit, KeyboardInterrupt):
+                raise
+            except BaseException as exc:
                 self._fatal_error(
                     exc, 'Fatal write error on datagram transport')
                 return

extlib/Python/Lib/asyncio/sslproto.py

@@ -5,7 +5,6 @@ try:
 except ImportError:  # pragma: no cover
     ssl = None
 
-from . import base_events
 from . import constants
 from . import protocols
 from . import transports
@@ -316,10 +315,9 @@ class _SSLProtocolTransport(transports._FlowControlMixin,
         self._closed = True
         self._ssl_protocol._start_shutdown()
 
-    def __del__(self):
+    def __del__(self, _warn=warnings.warn):
         if not self._closed:
-            warnings.warn(f"unclosed transport {self!r}", ResourceWarning,
+            _warn(f"unclosed transport {self!r}", ResourceWarning, source=self)
-                          source=self)
             self.close()
 
     def is_reading(self):
@@ -369,6 +367,12 @@ class _SSLProtocolTransport(transports._FlowControlMixin,
         """Return the current size of the write buffer."""
         return self._ssl_protocol._transport.get_write_buffer_size()
 
+    def get_write_buffer_limits(self):
+        """Get the high and low watermarks for write flow control. 
+        Return a tuple (low, high) where low and high are 
+        positive number of bytes."""
+        return self._ssl_protocol._transport.get_write_buffer_limits()
+
     @property
     def _protocol_paused(self):
         # Required for sendfile fallback pause_writing/resume_writing logic
@@ -499,7 +503,11 @@ class SSLProtocol(protocols.Protocol):
                 self._app_transport._closed = True
         self._transport = None
         self._app_transport = None
+        if getattr(self, '_handshake_timeout_handle', None):
+            self._handshake_timeout_handle.cancel()
         self._wakeup_waiter(exc)
+        self._app_protocol = None
+        self._sslpipe = None
 
     def pause_writing(self):
         """Called when the low-level transport's buffer goes over
@@ -524,7 +532,9 @@ class SSLProtocol(protocols.Protocol):
 
         try:
             ssldata, appdata = self._sslpipe.feed_ssldata(data)
-        except Exception as e:
+        except (SystemExit, KeyboardInterrupt):
+            raise
+        except BaseException as e:
             self._fatal_error(e, 'SSL error in data received')
             return
 
@@ -539,7 +549,9 @@ class SSLProtocol(protocols.Protocol):
                             self._app_protocol, chunk)
                     else:
                         self._app_protocol.data_received(chunk)
-                except Exception as ex:
+                except (SystemExit, KeyboardInterrupt):
+                    raise
+                except BaseException as ex:
                     self._fatal_error(
                         ex, 'application protocol failed to receive SSL data')
                     return
@@ -625,7 +637,9 @@ class SSLProtocol(protocols.Protocol):
                 raise handshake_exc
 
             peercert = sslobj.getpeercert()
-        except Exception as exc:
+        except (SystemExit, KeyboardInterrupt):
+            raise
+        except BaseException as exc:
             if isinstance(exc, ssl.CertificateError):
                 msg = 'SSL handshake failed on verifying the certificate'
             else:
@@ -688,7 +702,9 @@ class SSLProtocol(protocols.Protocol):
                 # delete it and reduce the outstanding buffer size.
                 del self._write_backlog[0]
                 self._write_buffer_size -= len(data)
-        except Exception as exc:
+        except (SystemExit, KeyboardInterrupt):
+            raise
+        except BaseException as exc:
             if self._in_handshake:
                 # Exceptions will be re-raised in _on_handshake_complete.
                 self._on_handshake_complete(exc)
@@ -696,7 +712,7 @@ class SSLProtocol(protocols.Protocol):
                 self._fatal_error(exc, 'Fatal error on SSL transport')
 
     def _fatal_error(self, exc, message='Fatal error on transport'):
-        if isinstance(exc, base_events._FATAL_ERROR_IGNORE):
+        if isinstance(exc, OSError):
             if self._loop.get_debug():
                 logger.debug("%r: %s", self, message, exc_info=True)
         else:

extlib/Python/Lib/asyncio/streams.py

@@ -1,16 +1,19 @@
 __all__ = (
     'StreamReader', 'StreamWriter', 'StreamReaderProtocol',
-    'open_connection', 'start_server',
+    'open_connection', 'start_server')
-    'IncompleteReadError', 'LimitOverrunError',
-)
 
 import socket
+import sys
+import warnings
+import weakref
 
 if hasattr(socket, 'AF_UNIX'):
     __all__ += ('open_unix_connection', 'start_unix_server')
 
 from . import coroutines
 from . import events
+from . import exceptions
+from . import format_helpers
 from . import protocols
 from .log import logger
 from .tasks import sleep
@@ -19,37 +22,6 @@ from .tasks import sleep
 _DEFAULT_LIMIT = 2 ** 16  # 64 KiB
 
 
-class IncompleteReadError(EOFError):
-    """
-    Incomplete read error. Attributes:
-
-    - partial: read bytes string before the end of stream was reached
-    - expected: total number of expected bytes (or None if unknown)
-    """
-    def __init__(self, partial, expected):
-        super().__init__(f'{len(partial)} bytes read on a total of '
-                         f'{expected!r} expected bytes')
-        self.partial = partial
-        self.expected = expected
-
-    def __reduce__(self):
-        return type(self), (self.partial, self.expected)
-
-
-class LimitOverrunError(Exception):
-    """Reached the buffer limit while looking for a separator.
-
-    Attributes:
-    - consumed: total number of to be consumed bytes.
-    """
-    def __init__(self, message, consumed):
-        super().__init__(message)
-        self.consumed = consumed
-
-    def __reduce__(self):
-        return type(self), (self.args[0], self.consumed)
-
-
 async def open_connection(host=None, port=None, *,
                           loop=None, limit=_DEFAULT_LIMIT, **kwds):
     """A wrapper for create_connection() returning a (reader, writer) pair.
@@ -71,6 +43,10 @@ async def open_connection(host=None, port=None, *,
     """
     if loop is None:
         loop = events.get_event_loop()
+    else:
+        warnings.warn("The loop argument is deprecated since Python 3.8, "
+                      "and scheduled for removal in Python 3.10.",
+                      DeprecationWarning, stacklevel=2)
     reader = StreamReader(limit=limit, loop=loop)
     protocol = StreamReaderProtocol(reader, loop=loop)
     transport, _ = await loop.create_connection(
@@ -104,6 +80,10 @@ async def start_server(client_connected_cb, host=None, port=None, *,
     """
     if loop is None:
         loop = events.get_event_loop()
+    else:
+        warnings.warn("The loop argument is deprecated since Python 3.8, "
+                      "and scheduled for removal in Python 3.10.",
+                      DeprecationWarning, stacklevel=2)
 
     def factory():
         reader = StreamReader(limit=limit, loop=loop)
@@ -122,6 +102,10 @@ if hasattr(socket, 'AF_UNIX'):
         """Similar to `open_connection` but works with UNIX Domain Sockets."""
         if loop is None:
             loop = events.get_event_loop()
+        else:
+            warnings.warn("The loop argument is deprecated since Python 3.8, "
+                          "and scheduled for removal in Python 3.10.",
+                          DeprecationWarning, stacklevel=2)
         reader = StreamReader(limit=limit, loop=loop)
         protocol = StreamReaderProtocol(reader, loop=loop)
         transport, _ = await loop.create_unix_connection(
@@ -134,6 +118,10 @@ if hasattr(socket, 'AF_UNIX'):
         """Similar to `start_server` but works with UNIX Domain Sockets."""
         if loop is None:
             loop = events.get_event_loop()
+        else:
+            warnings.warn("The loop argument is deprecated since Python 3.8, "
+                          "and scheduled for removal in Python 3.10.",
+                          DeprecationWarning, stacklevel=2)
 
         def factory():
             reader = StreamReader(limit=limit, loop=loop)
@@ -208,6 +196,9 @@ class FlowControlMixin(protocols.Protocol):
         self._drain_waiter = waiter
         await waiter
 
+    def _get_close_waiter(self, stream):
+        raise NotImplementedError
+
 
 class StreamReaderProtocol(FlowControlMixin, protocols.Protocol):
     """Helper class to adapt between Protocol and StreamReader.
@@ -218,46 +209,86 @@ class StreamReaderProtocol(FlowControlMixin, protocols.Protocol):
     call inappropriate methods of the protocol.)
     """
 
+    _source_traceback = None
+
     def __init__(self, stream_reader, client_connected_cb=None, loop=None):
         super().__init__(loop=loop)
-        self._stream_reader = stream_reader
+        if stream_reader is not None:
+            self._stream_reader_wr = weakref.ref(stream_reader)
+            self._source_traceback = stream_reader._source_traceback
+        else:
+            self._stream_reader_wr = None
+        if client_connected_cb is not None:
+            # This is a stream created by the `create_server()` function.
+            # Keep a strong reference to the reader until a connection
+            # is established.
+            self._strong_reader = stream_reader
+        self._reject_connection = False
         self._stream_writer = None
+        self._transport = None
         self._client_connected_cb = client_connected_cb
         self._over_ssl = False
         self._closed = self._loop.create_future()
 
+    @property
+    def _stream_reader(self):
+        if self._stream_reader_wr is None:
+            return None
+        return self._stream_reader_wr()
+
     def connection_made(self, transport):
-        self._stream_reader.set_transport(transport)
+        if self._reject_connection:
+            context = {
+                'message': ('An open stream was garbage collected prior to '
+                            'establishing network connection; '
+                            'call "stream.close()" explicitly.')
+            }
+            if self._source_traceback:
+                context['source_traceback'] = self._source_traceback
+            self._loop.call_exception_handler(context)
+            transport.abort()
+            return
+        self._transport = transport
+        reader = self._stream_reader
+        if reader is not None:
+            reader.set_transport(transport)
         self._over_ssl = transport.get_extra_info('sslcontext') is not None
         if self._client_connected_cb is not None:
             self._stream_writer = StreamWriter(transport, self,
-                                               self._stream_reader,
+                                               reader,
                                                self._loop)
-            res = self._client_connected_cb(self._stream_reader,
+            res = self._client_connected_cb(reader,
                                             self._stream_writer)
             if coroutines.iscoroutine(res):
                 self._loop.create_task(res)
+            self._strong_reader = None
 
     def connection_lost(self, exc):
-        if self._stream_reader is not None:
+        reader = self._stream_reader
+        if reader is not None:
             if exc is None:
-                self._stream_reader.feed_eof()
+                reader.feed_eof()
             else:
-                self._stream_reader.set_exception(exc)
+                reader.set_exception(exc)
         if not self._closed.done():
             if exc is None:
                 self._closed.set_result(None)
             else:
                 self._closed.set_exception(exc)
         super().connection_lost(exc)
-        self._stream_reader = None
+        self._stream_reader_wr = None
         self._stream_writer = None
+        self._transport = None
 
     def data_received(self, data):
-        self._stream_reader.feed_data(data)
+        reader = self._stream_reader
+        if reader is not None:
+            reader.feed_data(data)
 
     def eof_received(self):
-        self._stream_reader.feed_eof()
+        reader = self._stream_reader
+        if reader is not None:
+            reader.feed_eof()
         if self._over_ssl:
             # Prevent a warning in SSLProtocol.eof_received:
             # "returning true from eof_received()
@@ -265,6 +296,9 @@ class StreamReaderProtocol(FlowControlMixin, protocols.Protocol):
             return False
         return True
 
+    def _get_close_waiter(self, stream):
+        return self._closed
+
     def __del__(self):
         # Prevent reports about unhandled exceptions.
         # Better than self._closed._log_traceback = False hack
@@ -290,6 +324,8 @@ class StreamWriter:
         assert reader is None or isinstance(reader, StreamReader)
         self._reader = reader
         self._loop = loop
+        self._complete_fut = self._loop.create_future()
+        self._complete_fut.set_result(None)
 
     def __repr__(self):
         info = [self.__class__.__name__, f'transport={self._transport!r}']
@@ -320,7 +356,7 @@ class StreamWriter:
         return self._transport.is_closing()
 
     async def wait_closed(self):
-        await self._protocol._closed
+        await self._protocol._get_close_waiter(self)
 
     def get_extra_info(self, name, default=None):
         return self._transport.get_extra_info(name, default)
@@ -338,18 +374,23 @@ class StreamWriter:
             if exc is not None:
                 raise exc
         if self._transport.is_closing():
+            # Wait for protocol.connection_lost() call
+            # Raise connection closing error if any,
+            # ConnectionResetError otherwise
             # Yield to the event loop so connection_lost() may be
             # called.  Without this, _drain_helper() would return
             # immediately, and code that calls
             #     write(...); await drain()
             # in a loop would never call connection_lost(), so it
             # would not see an error when the socket is closed.
-            await sleep(0, loop=self._loop)
+            await sleep(0)
         await self._protocol._drain_helper()
 
 
 class StreamReader:
 
+    _source_traceback = None
+
     def __init__(self, limit=_DEFAULT_LIMIT, loop=None):
         # The line length limit is  a security feature;
         # it also doubles as half the buffer limit.
@@ -368,6 +409,9 @@ class StreamReader:
         self._exception = None
         self._transport = None
         self._paused = False
+        if self._loop.get_debug():
+            self._source_traceback = format_helpers.extract_stack(
+                sys._getframe(1))
 
     def __repr__(self):
         info = ['StreamReader']
@@ -494,9 +538,9 @@ class StreamReader:
         seplen = len(sep)
         try:
             line = await self.readuntil(sep)
-        except IncompleteReadError as e:
+        except exceptions.IncompleteReadError as e:
             return e.partial
-        except LimitOverrunError as e:
+        except exceptions.LimitOverrunError as e:
             if self._buffer.startswith(sep, e.consumed):
                 del self._buffer[:e.consumed + seplen]
             else:
@@ -571,7 +615,7 @@ class StreamReader:
                 # see upper comment for explanation.
                 offset = buflen + 1 - seplen
                 if offset > self._limit:
-                    raise LimitOverrunError(
+                    raise exceptions.LimitOverrunError(
                         'Separator is not found, and chunk exceed the limit',
                         offset)
 
@@ -582,13 +626,13 @@ class StreamReader:
             if self._eof:
                 chunk = bytes(self._buffer)
                 self._buffer.clear()
-                raise IncompleteReadError(chunk, None)
+                raise exceptions.IncompleteReadError(chunk, None)
 
             # _wait_for_data() will resume reading if stream was paused.
             await self._wait_for_data('readuntil')
 
         if isep > self._limit:
-            raise LimitOverrunError(
+            raise exceptions.LimitOverrunError(
                 'Separator is found, but chunk is longer than limit', isep)
 
         chunk = self._buffer[:isep + seplen]
@@ -674,7 +718,7 @@ class StreamReader:
             if self._eof:
                 incomplete = bytes(self._buffer)
                 self._buffer.clear()
-                raise IncompleteReadError(incomplete, n)
+                raise exceptions.IncompleteReadError(incomplete, n)
 
             await self._wait_for_data('readexactly')
 

extlib/Python/Lib/asyncio/subprocess.py

@@ -1,6 +1,7 @@
 __all__ = 'create_subprocess_exec', 'create_subprocess_shell'
 
 import subprocess
+import warnings
 
 from . import events
 from . import protocols
@@ -25,6 +26,7 @@ class SubprocessStreamProtocol(streams.FlowControlMixin,
         self._transport = None
         self._process_exited = False
         self._pipe_fds = []
+        self._stdin_closed = self._loop.create_future()
 
     def __repr__(self):
         info = [self.__class__.__name__]
@@ -76,6 +78,10 @@ class SubprocessStreamProtocol(streams.FlowControlMixin,
             if pipe is not None:
                 pipe.close()
             self.connection_lost(exc)
+            if exc is None:
+                self._stdin_closed.set_result(None)
+            else:
+                self._stdin_closed.set_exception(exc)
             return
         if fd == 1:
             reader = self.stdout
@@ -102,6 +108,10 @@ class SubprocessStreamProtocol(streams.FlowControlMixin,
             self._transport.close()
             self._transport = None
 
+    def _get_close_waiter(self, stream):
+        if stream is self.stdin:
+            return self._stdin_closed
+
 
 class Process:
     def __init__(self, transport, protocol, loop):
@@ -183,8 +193,8 @@ class Process:
             stderr = self._read_stream(2)
         else:
             stderr = self._noop()
-        stdin, stdout, stderr = await tasks.gather(stdin, stdout, stderr,
+        stdin, stdout, stderr = await tasks._gather(stdin, stdout, stderr,
-                                                   loop=self._loop)
+                                                    loop=self._loop)
         await self.wait()
         return (stdout, stderr)
 
@@ -194,6 +204,13 @@ async def create_subprocess_shell(cmd, stdin=None, stdout=None, stderr=None,
                                   **kwds):
     if loop is None:
         loop = events.get_event_loop()
+    else:
+        warnings.warn("The loop argument is deprecated since Python 3.8 "
+                      "and scheduled for removal in Python 3.10.",
+                      DeprecationWarning,
+                      stacklevel=2
+        )
+
     protocol_factory = lambda: SubprocessStreamProtocol(limit=limit,
                                                         loop=loop)
     transport, protocol = await loop.subprocess_shell(
@@ -208,6 +225,12 @@ async def create_subprocess_exec(program, *args, stdin=None, stdout=None,
                                  limit=streams._DEFAULT_LIMIT, **kwds):
     if loop is None:
         loop = events.get_event_loop()
+    else:
+        warnings.warn("The loop argument is deprecated since Python 3.8 "
+                      "and scheduled for removal in Python 3.10.",
+                      DeprecationWarning,
+                      stacklevel=2
+        )
     protocol_factory = lambda: SubprocessStreamProtocol(limit=limit,
                                                         loop=loop)
     transport, protocol = await loop.subprocess_exec(

extlib/Python/Lib/asyncio/tasks.py

@@ -13,15 +13,23 @@ import concurrent.futures
 import contextvars
 import functools
 import inspect
+import itertools
 import types
 import warnings
 import weakref
+from types import GenericAlias
 
 from . import base_tasks
 from . import coroutines
 from . import events
+from . import exceptions
 from . import futures
-from .coroutines import coroutine
+from .coroutines import _is_coroutine
+
+# Helper to generate new task names
+# This uses itertools.count() instead of a "+= 1" operation because the latter
+# is not thread safe. See bpo-11866 for a longer explanation.
+_task_name_counter = itertools.count(1).__next__
 
 
 def current_task(loop=None):
@@ -35,7 +43,22 @@ def all_tasks(loop=None):
     """Return a set of all tasks for the loop."""
     if loop is None:
         loop = events.get_running_loop()
-    return {t for t in _all_tasks
+    # Looping over a WeakSet (_all_tasks) isn't safe as it can be updated from another
+    # thread while we do so. Therefore we cast it to list prior to filtering. The list
+    # cast itself requires iteration, so we repeat it several times ignoring
+    # RuntimeErrors (which are not very likely to occur). See issues 34970 and 36607 for
+    # details.
+    i = 0
+    while True:
+        try:
+            tasks = list(_all_tasks)
+        except RuntimeError:
+            i += 1
+            if i >= 1000:
+                raise
+        else:
+            break
+    return {t for t in tasks
             if futures._get_loop(t) is loop and not t.done()}
 
 
@@ -45,7 +68,32 @@ def _all_tasks_compat(loop=None):
     # method.
     if loop is None:
         loop = events.get_event_loop()
-    return {t for t in _all_tasks if futures._get_loop(t) is loop}
+    # Looping over a WeakSet (_all_tasks) isn't safe as it can be updated from another
+    # thread while we do so. Therefore we cast it to list prior to filtering. The list
+    # cast itself requires iteration, so we repeat it several times ignoring
+    # RuntimeErrors (which are not very likely to occur). See issues 34970 and 36607 for
+    # details.
+    i = 0
+    while True:
+        try:
+            tasks = list(_all_tasks)
+        except RuntimeError:
+            i += 1
+            if i >= 1000:
+                raise
+        else:
+            break
+    return {t for t in tasks if futures._get_loop(t) is loop}
+
+
+def _set_task_name(task, name):
+    if name is not None:
+        try:
+            set_name = task.set_name
+        except AttributeError:
+            pass
+        else:
+            set_name(name)
 
 
 class Task(futures._PyFuture):  # Inherit Python Task implementation
@@ -66,35 +114,7 @@ class Task(futures._PyFuture):  # Inherit Python Task implementation
     # status is still pending
     _log_destroy_pending = True
 
-    @classmethod
+    def __init__(self, coro, *, loop=None, name=None):
-    def current_task(cls, loop=None):
-        """Return the currently running task in an event loop or None.
-
-        By default the current task for the current event loop is returned.
-
-        None is returned when called not in the context of a Task.
-        """
-        warnings.warn("Task.current_task() is deprecated, "
-                      "use asyncio.current_task() instead",
-                      PendingDeprecationWarning,
-                      stacklevel=2)
-        if loop is None:
-            loop = events.get_event_loop()
-        return current_task(loop)
-
-    @classmethod
-    def all_tasks(cls, loop=None):
-        """Return a set of all tasks for an event loop.
-
-        By default all tasks for the current event loop are returned.
-        """
-        warnings.warn("Task.all_tasks() is deprecated, "
-                      "use asyncio.all_tasks() instead",
-                      PendingDeprecationWarning,
-                      stacklevel=2)
-        return _all_tasks_compat(loop)
-
-    def __init__(self, coro, *, loop=None):
         super().__init__(loop=loop)
         if self._source_traceback:
             del self._source_traceback[-1]
@@ -104,6 +124,11 @@ class Task(futures._PyFuture):  # Inherit Python Task implementation
             self._log_destroy_pending = False
             raise TypeError(f"a coroutine was expected, got {coro!r}")
 
+        if name is None:
+            self._name = f'Task-{_task_name_counter()}'
+        else:
+            self._name = str(name)
+
         self._must_cancel = False
         self._fut_waiter = None
         self._coro = coro
@@ -123,9 +148,20 @@ class Task(futures._PyFuture):  # Inherit Python Task implementation
             self._loop.call_exception_handler(context)
         super().__del__()
 
+    __class_getitem__ = classmethod(GenericAlias)
+
     def _repr_info(self):
         return base_tasks._task_repr_info(self)
 
+    def get_coro(self):
+        return self._coro
+
+    def get_name(self):
+        return self._name
+
+    def set_name(self, value):
+        self._name = str(value)
+
     def set_result(self, result):
         raise RuntimeError('Task does not support set_result operation')
 
@@ -166,7 +202,7 @@ class Task(futures._PyFuture):  # Inherit Python Task implementation
         """
         return base_tasks._task_print_stack(self, limit, file)
 
-    def cancel(self):
+    def cancel(self, msg=None):
         """Request that this task cancel itself.
 
         This arranges for a CancelledError to be thrown into the
@@ -190,22 +226,23 @@ class Task(futures._PyFuture):  # Inherit Python Task implementation
         if self.done():
             return False
         if self._fut_waiter is not None:
-            if self._fut_waiter.cancel():
+            if self._fut_waiter.cancel(msg=msg):
                 # Leave self._fut_waiter; it may be a Task that
                 # catches and ignores the cancellation so we may have
                 # to cancel it again later.
                 return True
         # It must be the case that self.__step is already scheduled.
         self._must_cancel = True
+        self._cancel_message = msg
         return True
 
     def __step(self, exc=None):
         if self.done():
-            raise futures.InvalidStateError(
+            raise exceptions.InvalidStateError(
                 f'_step(): already done: {self!r}, {exc!r}')
         if self._must_cancel:
-            if not isinstance(exc, futures.CancelledError):
+            if not isinstance(exc, exceptions.CancelledError):
-                exc = futures.CancelledError()
+                exc = self._make_cancelled_error()
             self._must_cancel = False
         coro = self._coro
         self._fut_waiter = None
@@ -223,16 +260,18 @@ class Task(futures._PyFuture):  # Inherit Python Task implementation
             if self._must_cancel:
                 # Task is cancelled right before coro stops.
                 self._must_cancel = False
-                super().set_exception(futures.CancelledError())
+                super().cancel(msg=self._cancel_message)
             else:
                 super().set_result(exc.value)
-        except futures.CancelledError:
+        except exceptions.CancelledError as exc:
+            # Save the original exception so we can chain it later.
+            self._cancelled_exc = exc
             super().cancel()  # I.e., Future.cancel(self).
-        except Exception as exc:
+        except (KeyboardInterrupt, SystemExit) as exc:
-            super().set_exception(exc)
-        except BaseException as exc:
             super().set_exception(exc)
             raise
+        except BaseException as exc:
+            super().set_exception(exc)
         else:
             blocking = getattr(result, '_asyncio_future_blocking', None)
             if blocking is not None:
@@ -255,7 +294,8 @@ class Task(futures._PyFuture):  # Inherit Python Task implementation
                             self.__wakeup, context=self._context)
                         self._fut_waiter = result
                         if self._must_cancel:
-                            if self._fut_waiter.cancel():
+                            if self._fut_waiter.cancel(
+                                    msg=self._cancel_message):
                                 self._must_cancel = False
                 else:
                     new_exc = RuntimeError(
@@ -286,7 +326,7 @@ class Task(futures._PyFuture):  # Inherit Python Task implementation
     def __wakeup(self, future):
         try:
             future.result()
-        except Exception as exc:
+        except BaseException as exc:
             # This may also be a cancellation.
             self.__step(exc)
         else:
@@ -312,13 +352,15 @@ else:
     Task = _CTask = _asyncio.Task
 
 
-def create_task(coro):
+def create_task(coro, *, name=None):
     """Schedule the execution of a coroutine object in a spawn task.
 
     Return a Task object.
     """
     loop = events.get_running_loop()
-    return loop.create_task(coro)
+    task = loop.create_task(coro)
+    _set_task_name(task, name)
+    return task
 
 
 # wait() and as_completed() similar to those in PEP 3148.
@@ -331,7 +373,7 @@ ALL_COMPLETED = concurrent.futures.ALL_COMPLETED
 async def wait(fs, *, loop=None, timeout=None, return_when=ALL_COMPLETED):
     """Wait for the Futures and coroutines given by fs to complete.
 
-    The sequence futures must not be empty.
+    The fs iterable must not be empty.
 
     Coroutines will be wrapped in Tasks.
 
@@ -352,9 +394,21 @@ async def wait(fs, *, loop=None, timeout=None, return_when=ALL_COMPLETED):
         raise ValueError(f'Invalid return_when value: {return_when}')
 
     if loop is None:
-        loop = events.get_event_loop()
+        loop = events.get_running_loop()
+    else:
+        warnings.warn("The loop argument is deprecated since Python 3.8, "
+                      "and scheduled for removal in Python 3.10.",
+                      DeprecationWarning, stacklevel=2)
 
-    fs = {ensure_future(f, loop=loop) for f in set(fs)}
+    fs = set(fs)
+
+    if any(coroutines.iscoroutine(f) for f in fs):
+        warnings.warn("The explicit passing of coroutine objects to "
+                      "asyncio.wait() is deprecated since Python 3.8, and "
+                      "scheduled for removal in Python 3.11.",
+                      DeprecationWarning, stacklevel=2)
+
+    fs = {ensure_future(f, loop=loop) for f in fs}
 
     return await _wait(fs, timeout, return_when, loop)
 
@@ -378,7 +432,11 @@ async def wait_for(fut, timeout, *, loop=None):
     This function is a coroutine.
     """
     if loop is None:
-        loop = events.get_event_loop()
+        loop = events.get_running_loop()
+    else:
+        warnings.warn("The loop argument is deprecated since Python 3.8, "
+                      "and scheduled for removal in Python 3.10.",
+                      DeprecationWarning, stacklevel=2)
 
     if timeout is None:
         return await fut
@@ -389,8 +447,11 @@ async def wait_for(fut, timeout, *, loop=None):
         if fut.done():
             return fut.result()
 
-        fut.cancel()
+        await _cancel_and_wait(fut, loop=loop)
-        raise futures.TimeoutError()
+        try:
+            return fut.result()
+        except exceptions.CancelledError as exc:
+            raise exceptions.TimeoutError() from exc
 
     waiter = loop.create_future()
     timeout_handle = loop.call_later(timeout, _release_waiter, waiter)
@@ -403,10 +464,16 @@ async def wait_for(fut, timeout, *, loop=None):
         # wait until the future completes or the timeout
         try:
             await waiter
-        except futures.CancelledError:
+        except exceptions.CancelledError:
-            fut.remove_done_callback(cb)
+            if fut.done():
-            fut.cancel()
+                return fut.result()
-            raise
+            else:
+                fut.remove_done_callback(cb)
+                # We must ensure that the task is not running
+                # after wait_for() returns.
+                # See https://bugs.python.org/issue32751
+                await _cancel_and_wait(fut, loop=loop)
+                raise
 
         if fut.done():
             return fut.result()
@@ -416,7 +483,13 @@ async def wait_for(fut, timeout, *, loop=None):
             # after wait_for() returns.
             # See https://bugs.python.org/issue32751
             await _cancel_and_wait(fut, loop=loop)
-            raise futures.TimeoutError()
+            # In case task cancellation failed with some
+            # exception, we should re-raise it
+            # See https://bugs.python.org/issue40607
+            try:
+                return fut.result()
+            except exceptions.CancelledError as exc:
+                raise exceptions.TimeoutError() from exc
     finally:
         timeout_handle.cancel()
 
@@ -453,10 +526,11 @@ async def _wait(fs, timeout, return_when, loop):
     finally:
         if timeout_handle is not None:
             timeout_handle.cancel()
+        for f in fs:
+            f.remove_done_callback(_on_completion)
 
     done, pending = set(), set()
     for f in fs:
-        f.remove_done_callback(_on_completion)
         if f.done():
             done.add(f)
         else:
@@ -500,11 +574,19 @@ def as_completed(fs, *, loop=None, timeout=None):
     Note: The futures 'f' are not necessarily members of fs.
     """
     if futures.isfuture(fs) or coroutines.iscoroutine(fs):
-        raise TypeError(f"expect a list of futures, not {type(fs).__name__}")
+        raise TypeError(f"expect an iterable of futures, not {type(fs).__name__}")
-    loop = loop if loop is not None else events.get_event_loop()
+
-    todo = {ensure_future(f, loop=loop) for f in set(fs)}
+    if loop is not None:
+        warnings.warn("The loop argument is deprecated since Python 3.8, "
+                      "and scheduled for removal in Python 3.10.",
+                      DeprecationWarning, stacklevel=2)
+
     from .queues import Queue  # Import here to avoid circular import problem.
     done = Queue(loop=loop)
+
+    if loop is None:
+        loop = events.get_event_loop()
+    todo = {ensure_future(f, loop=loop) for f in set(fs)}
     timeout_handle = None
 
     def _on_timeout():
@@ -525,7 +607,7 @@ def as_completed(fs, *, loop=None, timeout=None):
         f = await done.get()
         if f is None:
             # Dummy value from _on_timeout().
-            raise futures.TimeoutError
+            raise exceptions.TimeoutError
         return f.result()  # May raise f.exception().
 
     for f in todo:
@@ -550,12 +632,18 @@ def __sleep0():
 
 async def sleep(delay, result=None, *, loop=None):
     """Coroutine that completes after a given time (in seconds)."""
+    if loop is not None:
+        warnings.warn("The loop argument is deprecated since Python 3.8, "
+                      "and scheduled for removal in Python 3.10.",
+                      DeprecationWarning, stacklevel=2)
+
     if delay <= 0:
         await __sleep0()
         return result
 
     if loop is None:
-        loop = events.get_event_loop()
+        loop = events.get_running_loop()
+
     future = loop.create_future()
     h = loop.call_later(delay,
                         futures._set_result_unless_cancelled,
@@ -580,7 +668,8 @@ def ensure_future(coro_or_future, *, loop=None):
         return task
     elif futures.isfuture(coro_or_future):
         if loop is not None and loop is not futures._get_loop(coro_or_future):
-            raise ValueError('loop argument must agree with Future')
+            raise ValueError('The future belongs to a different loop than '
+                             'the one specified as the loop argument')
         return coro_or_future
     elif inspect.isawaitable(coro_or_future):
         return ensure_future(_wrap_awaitable(coro_or_future), loop=loop)
@@ -589,7 +678,7 @@ def ensure_future(coro_or_future, *, loop=None):
                         'required')
 
 
-@coroutine
+@types.coroutine
 def _wrap_awaitable(awaitable):
     """Helper for asyncio.ensure_future().
 
@@ -598,6 +687,8 @@ def _wrap_awaitable(awaitable):
     """
     return (yield from awaitable.__await__())
 
+_wrap_awaitable._is_coroutine = _is_coroutine
+
 
 class _GatheringFuture(futures.Future):
     """Helper for gather().
@@ -612,12 +703,12 @@ class _GatheringFuture(futures.Future):
         self._children = children
         self._cancel_requested = False
 
-    def cancel(self):
+    def cancel(self, msg=None):
         if self.done():
             return False
         ret = False
         for child in self._children:
-            if child.cancel():
+            if child.cancel(msg=msg):
                 ret = True
         if ret:
             # If any child tasks were actually cancelled, we should
@@ -649,7 +740,23 @@ def gather(*coros_or_futures, loop=None, return_exceptions=False):
     the outer Future is *not* cancelled in this case.  (This is to
     prevent the cancellation of one child to cause other children to
     be cancelled.)
+
+    If *return_exceptions* is False, cancelling gather() after it
+    has been marked done won't cancel any submitted awaitables.
+    For instance, gather can be marked done after propagating an
+    exception to the caller, therefore, calling ``gather.cancel()``
+    after catching an exception (raised by one of the awaitables) from
+    gather won't cancel any other awaitables.
     """
+    if loop is not None:
+        warnings.warn("The loop argument is deprecated since Python 3.8, "
+                      "and scheduled for removal in Python 3.10.",
+                      DeprecationWarning, stacklevel=2)
+
+    return _gather(*coros_or_futures, loop=loop, return_exceptions=return_exceptions)
+
+
+def _gather(*coros_or_futures, loop=None, return_exceptions=False):
     if not coros_or_futures:
         if loop is None:
             loop = events.get_event_loop()
@@ -661,7 +768,7 @@ def gather(*coros_or_futures, loop=None, return_exceptions=False):
         nonlocal nfinished
         nfinished += 1
 
-        if outer.done():
+        if outer is None or outer.done():
             if not fut.cancelled():
                 # Mark exception retrieved.
                 fut.exception()
@@ -672,7 +779,7 @@ def gather(*coros_or_futures, loop=None, return_exceptions=False):
                 # Check if 'fut' is cancelled first, as
                 # 'fut.exception()' will *raise* a CancelledError
                 # instead of returning it.
-                exc = futures.CancelledError()
+                exc = fut._make_cancelled_error()
                 outer.set_exception(exc)
                 return
             else:
@@ -688,10 +795,15 @@ def gather(*coros_or_futures, loop=None, return_exceptions=False):
 
             for fut in children:
                 if fut.cancelled():
-                    # Check if 'fut' is cancelled first, as
+                    # Check if 'fut' is cancelled first, as 'fut.exception()'
-                    # 'fut.exception()' will *raise* a CancelledError
+                    # will *raise* a CancelledError instead of returning it.
-                    # instead of returning it.
+                    # Also, since we're adding the exception return value
-                    res = futures.CancelledError()
+                    # to 'results' instead of raising it, don't bother
+                    # setting __context__.  This also lets us preserve
+                    # calling '_make_cancelled_error()' at most once.
+                    res = exceptions.CancelledError(
+                        '' if fut._cancel_message is None else
+                        fut._cancel_message)
                 else:
                     res = fut.exception()
                     if res is None:
@@ -702,7 +814,8 @@ def gather(*coros_or_futures, loop=None, return_exceptions=False):
                 # If gather is being cancelled we must propagate the
                 # cancellation regardless of *return_exceptions* argument.
                 # See issue 32684.
-                outer.set_exception(futures.CancelledError())
+                exc = fut._make_cancelled_error()
+                outer.set_exception(exc)
             else:
                 outer.set_result(results)
 
@@ -710,6 +823,7 @@ def gather(*coros_or_futures, loop=None, return_exceptions=False):
     children = []
     nfuts = 0
     nfinished = 0
+    outer = None  # bpo-46672
     for arg in coros_or_futures:
         if arg not in arg_to_fut:
             fut = ensure_future(arg, loop=loop)
@@ -762,6 +876,10 @@ def shield(arg, *, loop=None):
         except CancelledError:
             res = None
     """
+    if loop is not None:
+        warnings.warn("The loop argument is deprecated since Python 3.8, "
+                      "and scheduled for removal in Python 3.10.",
+                      DeprecationWarning, stacklevel=2)
     inner = ensure_future(arg, loop=loop)
     if inner.done():
         # Shortcut.
@@ -769,7 +887,7 @@ def shield(arg, *, loop=None):
     loop = futures._get_loop(inner)
     outer = loop.create_future()
 
-    def _done_callback(inner):
+    def _inner_done_callback(inner):
         if outer.cancelled():
             if not inner.cancelled():
                 # Mark inner's result as retrieved.
@@ -785,7 +903,13 @@ def shield(arg, *, loop=None):
             else:
                 outer.set_result(inner.result())
 
-    inner.add_done_callback(_done_callback)
+
+    def _outer_done_callback(outer):
+        if not inner.done():
+            inner.remove_done_callback(_inner_done_callback)
+
+    inner.add_done_callback(_inner_done_callback)
+    outer.add_done_callback(_outer_done_callback)
     return outer
 
 
@@ -801,7 +925,9 @@ def run_coroutine_threadsafe(coro, loop):
     def callback():
         try:
             futures._chain_future(ensure_future(coro, loop=loop), future)
-        except Exception as exc:
+        except (SystemExit, KeyboardInterrupt):
+            raise
+        except BaseException as exc:
             if future.set_running_or_notify_cancel():
                 future.set_exception(exc)
             raise

extlib/Python/Lib/asyncio/transports.py

@@ -9,6 +9,8 @@ __all__ = (
 class BaseTransport:
     """Base class for transports."""
 
+    __slots__ = ('_extra',)
+
     def __init__(self, extra=None):
         if extra is None:
             extra = {}
@@ -27,8 +29,8 @@ class BaseTransport:
 
         Buffered data will be flushed asynchronously.  No more data
         will be received.  After all buffered data is flushed, the
-        protocol's connection_lost() method will (eventually) called
+        protocol's connection_lost() method will (eventually) be
-        with None as its argument.
+        called with None as its argument.
         """
         raise NotImplementedError
 
@@ -44,6 +46,8 @@ class BaseTransport:
 class ReadTransport(BaseTransport):
     """Interface for read-only transports."""
 
+    __slots__ = ()
+
     def is_reading(self):
         """Return True if the transport is receiving."""
         raise NotImplementedError
@@ -68,6 +72,8 @@ class ReadTransport(BaseTransport):
 class WriteTransport(BaseTransport):
     """Interface for write-only transports."""
 
+    __slots__ = ()
+
     def set_write_buffer_limits(self, high=None, low=None):
         """Set the high- and low-water limits for write flow control.
 
@@ -93,6 +99,12 @@ class WriteTransport(BaseTransport):
         """Return the current size of the write buffer."""
         raise NotImplementedError
 
+    def get_write_buffer_limits(self):
+        """Get the high and low watermarks for write flow control. 
+        Return a tuple (low, high) where low and high are 
+        positive number of bytes."""
+        raise NotImplementedError
+
     def write(self, data):
         """Write some data bytes to the transport.
 
@@ -154,10 +166,14 @@ class Transport(ReadTransport, WriteTransport):
     except writelines(), which calls write() in a loop.
     """
 
+    __slots__ = ()
+
 
 class DatagramTransport(BaseTransport):
     """Interface for datagram (UDP) transports."""
 
+    __slots__ = ()
+
     def sendto(self, data, addr=None):
         """Send data to the transport.
 
@@ -180,6 +196,8 @@ class DatagramTransport(BaseTransport):
 
 class SubprocessTransport(BaseTransport):
 
+    __slots__ = ()
+
     def get_pid(self):
         """Get subprocess id."""
         raise NotImplementedError
@@ -247,6 +265,8 @@ class _FlowControlMixin(Transport):
     resume_writing() may be called.
     """
 
+    __slots__ = ('_loop', '_protocol_paused', '_high_water', '_low_water')
+
     def __init__(self, extra=None, loop=None):
         super().__init__(extra)
         assert loop is not None
@@ -262,7 +282,9 @@ class _FlowControlMixin(Transport):
             self._protocol_paused = True
             try:
                 self._protocol.pause_writing()
-            except Exception as exc:
+            except (SystemExit, KeyboardInterrupt):
+                raise
+            except BaseException as exc:
                 self._loop.call_exception_handler({
                     'message': 'protocol.pause_writing() failed',
                     'exception': exc,
@@ -276,7 +298,9 @@ class _FlowControlMixin(Transport):
             self._protocol_paused = False
             try:
                 self._protocol.resume_writing()
-            except Exception as exc:
+            except (SystemExit, KeyboardInterrupt):
+                raise
+            except BaseException as exc:
                 self._loop.call_exception_handler({
                     'message': 'protocol.resume_writing() failed',
                     'exception': exc,

extlib/Python/Lib/asyncio/unix_events.py

@@ -2,6 +2,7 @@
 
 import errno
 import io
+import itertools
 import os
 import selectors
 import signal
@@ -12,12 +13,12 @@ import sys
 import threading
 import warnings
 
-
 from . import base_events
 from . import base_subprocess
 from . import constants
 from . import coroutines
 from . import events
+from . import exceptions
 from . import futures
 from . import selector_events
 from . import tasks
@@ -28,7 +29,9 @@ from .log import logger
 __all__ = (
     'SelectorEventLoop',
     'AbstractChildWatcher', 'SafeChildWatcher',
-    'FastChildWatcher', 'DefaultEventLoopPolicy',
+    'FastChildWatcher', 'PidfdChildWatcher',
+    'MultiLoopChildWatcher', 'ThreadedChildWatcher',
+    'DefaultEventLoopPolicy',
 )
 
 
@@ -98,7 +101,7 @@ class _UnixSelectorEventLoop(selector_events.BaseSelectorEventLoop):
 
         try:
             # Register a dummy signal handler to ask Python to write the signal
-            # number in the wakup file descriptor. _process_self_data() will
+            # number in the wakeup file descriptor. _process_self_data() will
             # read signal numbers from this file descriptor to handle signals.
             signal.signal(sig, _sighandler_noop)
 
@@ -168,8 +171,8 @@ class _UnixSelectorEventLoop(selector_events.BaseSelectorEventLoop):
         if not isinstance(sig, int):
             raise TypeError(f'sig must be an int, not {sig!r}')
 
-        if not (1 <= sig < signal.NSIG):
+        if sig not in signal.valid_signals():
-            raise ValueError(f'sig {sig} out of range(1, {signal.NSIG})')
+            raise ValueError(f'invalid signal number {sig}')
 
     def _make_read_pipe_transport(self, pipe, protocol, waiter=None,
                                   extra=None):
@@ -183,6 +186,13 @@ class _UnixSelectorEventLoop(selector_events.BaseSelectorEventLoop):
                                          stdin, stdout, stderr, bufsize,
                                          extra=None, **kwargs):
         with events.get_child_watcher() as watcher:
+            if not watcher.is_active():
+                # Check early.
+                # Raising exception before process creation
+                # prevents subprocess execution if the watcher
+                # is not ready to handle it.
+                raise RuntimeError("asyncio.get_child_watcher() is not activated, "
+                                   "subprocess support is not installed.")
             waiter = self.create_future()
             transp = _UnixSubprocessTransport(self, protocol, args, shell,
                                               stdin, stdout, stderr, bufsize,
@@ -193,7 +203,9 @@ class _UnixSelectorEventLoop(selector_events.BaseSelectorEventLoop):
                                       self._child_watcher_callback, transp)
             try:
                 await waiter
-            except Exception:
+            except (SystemExit, KeyboardInterrupt):
+                raise
+            except BaseException:
                 transp.close()
                 await transp._wait()
                 raise
@@ -311,24 +323,24 @@ class _UnixSelectorEventLoop(selector_events.BaseSelectorEventLoop):
             server._start_serving()
             # Skip one loop iteration so that all 'loop.add_reader'
             # go through.
-            await tasks.sleep(0, loop=self)
+            await tasks.sleep(0)
 
         return server
 
     async def _sock_sendfile_native(self, sock, file, offset, count):
         try:
             os.sendfile
-        except AttributeError as exc:
+        except AttributeError:
-            raise events.SendfileNotAvailableError(
+            raise exceptions.SendfileNotAvailableError(
                 "os.sendfile() is not available")
         try:
             fileno = file.fileno()
         except (AttributeError, io.UnsupportedOperation) as err:
-            raise events.SendfileNotAvailableError("not a regular file")
+            raise exceptions.SendfileNotAvailableError("not a regular file")
         try:
             fsize = os.fstat(fileno).st_size
-        except OSError as err:
+        except OSError:
-            raise events.SendfileNotAvailableError("not a regular file")
+            raise exceptions.SendfileNotAvailableError("not a regular file")
         blocksize = count if count else fsize
         if not blocksize:
             return 0  # empty file
@@ -382,14 +394,16 @@ class _UnixSelectorEventLoop(selector_events.BaseSelectorEventLoop):
                 # one being 'file' is not a regular mmap(2)-like
                 # file, in which case we'll fall back on using
                 # plain send().
-                err = events.SendfileNotAvailableError(
+                err = exceptions.SendfileNotAvailableError(
                     "os.sendfile call failed")
                 self._sock_sendfile_update_filepos(fileno, offset, total_sent)
                 fut.set_exception(err)
             else:
                 self._sock_sendfile_update_filepos(fileno, offset, total_sent)
                 fut.set_exception(exc)
-        except Exception as exc:
+        except (SystemExit, KeyboardInterrupt):
+            raise
+        except BaseException as exc:
             self._sock_sendfile_update_filepos(fileno, offset, total_sent)
             fut.set_exception(exc)
         else:
@@ -431,6 +445,7 @@ class _UnixReadPipeTransport(transports.ReadTransport):
         self._fileno = pipe.fileno()
         self._protocol = protocol
         self._closing = False
+        self._paused = False
 
         mode = os.fstat(self._fileno).st_mode
         if not (stat.S_ISFIFO(mode) or
@@ -492,10 +507,20 @@ class _UnixReadPipeTransport(transports.ReadTransport):
                 self._loop.call_soon(self._call_connection_lost, None)
 
     def pause_reading(self):
+        if self._closing or self._paused:
+            return
+        self._paused = True
         self._loop._remove_reader(self._fileno)
+        if self._loop.get_debug():
+            logger.debug("%r pauses reading", self)
 
     def resume_reading(self):
+        if self._closing or not self._paused:
+            return
+        self._paused = False
         self._loop._add_reader(self._fileno, self._read_ready)
+        if self._loop.get_debug():
+            logger.debug("%r resumes reading", self)
 
     def set_protocol(self, protocol):
         self._protocol = protocol
@@ -510,10 +535,9 @@ class _UnixReadPipeTransport(transports.ReadTransport):
         if not self._closing:
             self._close(None)
 
-    def __del__(self):
+    def __del__(self, _warn=warnings.warn):
         if self._pipe is not None:
-            warnings.warn(f"unclosed transport {self!r}", ResourceWarning,
+            _warn(f"unclosed transport {self!r}", ResourceWarning, source=self)
-                          source=self)
             self._pipe.close()
 
     def _fatal_error(self, exc, message='Fatal error on pipe transport'):
@@ -641,7 +665,9 @@ class _UnixWritePipeTransport(transports._FlowControlMixin,
                 n = os.write(self._fileno, data)
             except (BlockingIOError, InterruptedError):
                 n = 0
-            except Exception as exc:
+            except (SystemExit, KeyboardInterrupt):
+                raise
+            except BaseException as exc:
                 self._conn_lost += 1
                 self._fatal_error(exc, 'Fatal write error on pipe transport')
                 return
@@ -661,7 +687,9 @@ class _UnixWritePipeTransport(transports._FlowControlMixin,
             n = os.write(self._fileno, self._buffer)
         except (BlockingIOError, InterruptedError):
             pass
-        except Exception as exc:
+        except (SystemExit, KeyboardInterrupt):
+            raise
+        except BaseException as exc:
             self._buffer.clear()
             self._conn_lost += 1
             # Remove writer here, _fatal_error() doesn't it
@@ -706,10 +734,9 @@ class _UnixWritePipeTransport(transports._FlowControlMixin,
             # write_eof is all what we needed to close the write pipe
             self.write_eof()
 
-    def __del__(self):
+    def __del__(self, _warn=warnings.warn):
         if self._pipe is not None:
-            warnings.warn(f"unclosed transport {self!r}", ResourceWarning,
+            _warn(f"unclosed transport {self!r}", ResourceWarning, source=self)
-                          source=self)
             self._pipe.close()
 
     def abort(self):
@@ -717,7 +744,7 @@ class _UnixWritePipeTransport(transports._FlowControlMixin,
 
     def _fatal_error(self, exc, message='Fatal error on pipe transport'):
         # should be called by exception handler only
-        if isinstance(exc, base_events._FATAL_ERROR_IGNORE):
+        if isinstance(exc, OSError):
             if self._loop.get_debug():
                 logger.debug("%r: %s", self, message, exc_info=True)
         else:
@@ -758,12 +785,18 @@ class _UnixSubprocessTransport(base_subprocess.BaseSubprocessTransport):
             # other end).  Notably this is needed on AIX, and works
             # just fine on other platforms.
             stdin, stdin_w = socket.socketpair()
-        self._proc = subprocess.Popen(
+        try:
-            args, shell=shell, stdin=stdin, stdout=stdout, stderr=stderr,
+            self._proc = subprocess.Popen(
-            universal_newlines=False, bufsize=bufsize, **kwargs)
+                args, shell=shell, stdin=stdin, stdout=stdout, stderr=stderr,
-        if stdin_w is not None:
+                universal_newlines=False, bufsize=bufsize, **kwargs)
-            stdin.close()
+            if stdin_w is not None:
-            self._proc.stdin = open(stdin_w.detach(), 'wb', buffering=bufsize)
+                stdin.close()
+                self._proc.stdin = open(stdin_w.detach(), 'wb', buffering=bufsize)
+                stdin_w = None
+        finally:
+            if stdin_w is not None:
+                stdin.close()
+                stdin_w.close()
 
 
 class AbstractChildWatcher:
@@ -825,6 +858,15 @@ class AbstractChildWatcher:
         """
         raise NotImplementedError()
 
+    def is_active(self):
+        """Return ``True`` if the watcher is active and is used by the event loop.
+
+        Return True if the watcher is installed and ready to handle process exit
+        notifications.
+
+        """
+        raise NotImplementedError()
+
     def __enter__(self):
         """Enter the watcher's context and allow starting new processes
 
@@ -836,6 +878,98 @@ class AbstractChildWatcher:
         raise NotImplementedError()
 
 
+class PidfdChildWatcher(AbstractChildWatcher):
+    """Child watcher implementation using Linux's pid file descriptors.
+
+    This child watcher polls process file descriptors (pidfds) to await child
+    process termination. In some respects, PidfdChildWatcher is a "Goldilocks"
+    child watcher implementation. It doesn't require signals or threads, doesn't
+    interfere with any processes launched outside the event loop, and scales
+    linearly with the number of subprocesses launched by the event loop. The
+    main disadvantage is that pidfds are specific to Linux, and only work on
+    recent (5.3+) kernels.
+    """
+
+    def __init__(self):
+        self._loop = None
+        self._callbacks = {}
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exc_type, exc_value, exc_traceback):
+        pass
+
+    def is_active(self):
+        return self._loop is not None and self._loop.is_running()
+
+    def close(self):
+        self.attach_loop(None)
+
+    def attach_loop(self, loop):
+        if self._loop is not None and loop is None and self._callbacks:
+            warnings.warn(
+                'A loop is being detached '
+                'from a child watcher with pending handlers',
+                RuntimeWarning)
+        for pidfd, _, _ in self._callbacks.values():
+            self._loop._remove_reader(pidfd)
+            os.close(pidfd)
+        self._callbacks.clear()
+        self._loop = loop
+
+    def add_child_handler(self, pid, callback, *args):
+        existing = self._callbacks.get(pid)
+        if existing is not None:
+            self._callbacks[pid] = existing[0], callback, args
+        else:
+            pidfd = os.pidfd_open(pid)
+            self._loop._add_reader(pidfd, self._do_wait, pid)
+            self._callbacks[pid] = pidfd, callback, args
+
+    def _do_wait(self, pid):
+        pidfd, callback, args = self._callbacks.pop(pid)
+        self._loop._remove_reader(pidfd)
+        try:
+            _, status = os.waitpid(pid, 0)
+        except ChildProcessError:
+            # The child process is already reaped
+            # (may happen if waitpid() is called elsewhere).
+            returncode = 255
+            logger.warning(
+                "child process pid %d exit status already read: "
+                " will report returncode 255",
+                pid)
+        else:
+            returncode = _compute_returncode(status)
+
+        os.close(pidfd)
+        callback(pid, returncode, *args)
+
+    def remove_child_handler(self, pid):
+        try:
+            pidfd, _, _ = self._callbacks.pop(pid)
+        except KeyError:
+            return False
+        self._loop._remove_reader(pidfd)
+        os.close(pidfd)
+        return True
+
+
+def _compute_returncode(status):
+    if os.WIFSIGNALED(status):
+        # The child process died because of a signal.
+        return -os.WTERMSIG(status)
+    elif os.WIFEXITED(status):
+        # The child process exited (e.g sys.exit()).
+        return os.WEXITSTATUS(status)
+    else:
+        # The child exited, but we don't understand its status.
+        # This shouldn't happen, but if it does, let's just
+        # return that status; perhaps that helps debug it.
+        return status
+
+
 class BaseChildWatcher(AbstractChildWatcher):
 
     def __init__(self):
@@ -845,6 +979,9 @@ class BaseChildWatcher(AbstractChildWatcher):
     def close(self):
         self.attach_loop(None)
 
+    def is_active(self):
+        return self._loop is not None and self._loop.is_running()
+
     def _do_waitpid(self, expected_pid):
         raise NotImplementedError()
 
@@ -874,7 +1011,9 @@ class BaseChildWatcher(AbstractChildWatcher):
     def _sig_chld(self):
         try:
             self._do_waitpid_all()
-        except Exception as exc:
+        except (SystemExit, KeyboardInterrupt):
+            raise
+        except BaseException as exc:
             # self._loop should always be available here
             # as '_sig_chld' is added as a signal handler
             # in 'attach_loop'
@@ -883,19 +1022,6 @@ class BaseChildWatcher(AbstractChildWatcher):
                 'exception': exc,
             })
 
-    def _compute_returncode(self, status):
-        if os.WIFSIGNALED(status):
-            # The child process died because of a signal.
-            return -os.WTERMSIG(status)
-        elif os.WIFEXITED(status):
-            # The child process exited (e.g sys.exit()).
-            return os.WEXITSTATUS(status)
-        else:
-            # The child exited, but we don't understand its status.
-            # This shouldn't happen, but if it does, let's just
-            # return that status; perhaps that helps debug it.
-            return status
-
 
 class SafeChildWatcher(BaseChildWatcher):
     """'Safe' child watcher implementation.
@@ -919,11 +1045,6 @@ class SafeChildWatcher(BaseChildWatcher):
         pass
 
     def add_child_handler(self, pid, callback, *args):
-        if self._loop is None:
-            raise RuntimeError(
-                "Cannot add child handler, "
-                "the child watcher does not have a loop attached")
-
         self._callbacks[pid] = (callback, args)
 
         # Prevent a race condition in case the child is already terminated.
@@ -959,7 +1080,7 @@ class SafeChildWatcher(BaseChildWatcher):
                 # The child process is still alive.
                 return
 
-            returncode = self._compute_returncode(status)
+            returncode = _compute_returncode(status)
             if self._loop.get_debug():
                 logger.debug('process %s exited with returncode %s',
                              expected_pid, returncode)
@@ -1020,11 +1141,6 @@ class FastChildWatcher(BaseChildWatcher):
     def add_child_handler(self, pid, callback, *args):
         assert self._forks, "Must use the context manager"
 
-        if self._loop is None:
-            raise RuntimeError(
-                "Cannot add child handler, "
-                "the child watcher does not have a loop attached")
-
         with self._lock:
             try:
                 returncode = self._zombies.pop(pid)
@@ -1057,7 +1173,7 @@ class FastChildWatcher(BaseChildWatcher):
                     # A child process is still alive.
                     return
 
-                returncode = self._compute_returncode(status)
+                returncode = _compute_returncode(status)
 
             with self._lock:
                 try:
@@ -1086,6 +1202,220 @@ class FastChildWatcher(BaseChildWatcher):
                 callback(pid, returncode, *args)
 
 
+class MultiLoopChildWatcher(AbstractChildWatcher):
+    """A watcher that doesn't require running loop in the main thread.
+
+    This implementation registers a SIGCHLD signal handler on
+    instantiation (which may conflict with other code that
+    install own handler for this signal).
+
+    The solution is safe but it has a significant overhead when
+    handling a big number of processes (*O(n)* each time a
+    SIGCHLD is received).
+    """
+
+    # Implementation note:
+    # The class keeps compatibility with AbstractChildWatcher ABC
+    # To achieve this it has empty attach_loop() method
+    # and doesn't accept explicit loop argument
+    # for add_child_handler()/remove_child_handler()
+    # but retrieves the current loop by get_running_loop()
+
+    def __init__(self):
+        self._callbacks = {}
+        self._saved_sighandler = None
+
+    def is_active(self):
+        return self._saved_sighandler is not None
+
+    def close(self):
+        self._callbacks.clear()
+        if self._saved_sighandler is None:
+            return
+
+        handler = signal.getsignal(signal.SIGCHLD)
+        if handler != self._sig_chld:
+            logger.warning("SIGCHLD handler was changed by outside code")
+        else:
+            signal.signal(signal.SIGCHLD, self._saved_sighandler)
+        self._saved_sighandler = None
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        pass
+
+    def add_child_handler(self, pid, callback, *args):
+        loop = events.get_running_loop()
+        self._callbacks[pid] = (loop, callback, args)
+
+        # Prevent a race condition in case the child is already terminated.
+        self._do_waitpid(pid)
+
+    def remove_child_handler(self, pid):
+        try:
+            del self._callbacks[pid]
+            return True
+        except KeyError:
+            return False
+
+    def attach_loop(self, loop):
+        # Don't save the loop but initialize itself if called first time
+        # The reason to do it here is that attach_loop() is called from
+        # unix policy only for the main thread.
+        # Main thread is required for subscription on SIGCHLD signal
+        if self._saved_sighandler is not None:
+            return
+
+        self._saved_sighandler = signal.signal(signal.SIGCHLD, self._sig_chld)
+        if self._saved_sighandler is None:
+            logger.warning("Previous SIGCHLD handler was set by non-Python code, "
+                           "restore to default handler on watcher close.")
+            self._saved_sighandler = signal.SIG_DFL
+
+        # Set SA_RESTART to limit EINTR occurrences.
+        signal.siginterrupt(signal.SIGCHLD, False)
+
+    def _do_waitpid_all(self):
+        for pid in list(self._callbacks):
+            self._do_waitpid(pid)
+
+    def _do_waitpid(self, expected_pid):
+        assert expected_pid > 0
+
+        try:
+            pid, status = os.waitpid(expected_pid, os.WNOHANG)
+        except ChildProcessError:
+            # The child process is already reaped
+            # (may happen if waitpid() is called elsewhere).
+            pid = expected_pid
+            returncode = 255
+            logger.warning(
+                "Unknown child process pid %d, will report returncode 255",
+                pid)
+            debug_log = False
+        else:
+            if pid == 0:
+                # The child process is still alive.
+                return
+
+            returncode = _compute_returncode(status)
+            debug_log = True
+        try:
+            loop, callback, args = self._callbacks.pop(pid)
+        except KeyError:  # pragma: no cover
+            # May happen if .remove_child_handler() is called
+            # after os.waitpid() returns.
+            logger.warning("Child watcher got an unexpected pid: %r",
+                           pid, exc_info=True)
+        else:
+            if loop.is_closed():
+                logger.warning("Loop %r that handles pid %r is closed", loop, pid)
+            else:
+                if debug_log and loop.get_debug():
+                    logger.debug('process %s exited with returncode %s',
+                                 expected_pid, returncode)
+                loop.call_soon_threadsafe(callback, pid, returncode, *args)
+
+    def _sig_chld(self, signum, frame):
+        try:
+            self._do_waitpid_all()
+        except (SystemExit, KeyboardInterrupt):
+            raise
+        except BaseException:
+            logger.warning('Unknown exception in SIGCHLD handler', exc_info=True)
+
+
+class ThreadedChildWatcher(AbstractChildWatcher):
+    """Threaded child watcher implementation.
+
+    The watcher uses a thread per process
+    for waiting for the process finish.
+
+    It doesn't require subscription on POSIX signal
+    but a thread creation is not free.
+
+    The watcher has O(1) complexity, its performance doesn't depend
+    on amount of spawn processes.
+    """
+
+    def __init__(self):
+        self._pid_counter = itertools.count(0)
+        self._threads = {}
+
+    def is_active(self):
+        return True
+
+    def close(self):
+        self._join_threads()
+
+    def _join_threads(self):
+        """Internal: Join all non-daemon threads"""
+        threads = [thread for thread in list(self._threads.values())
+                   if thread.is_alive() and not thread.daemon]
+        for thread in threads:
+            thread.join()
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        pass
+
+    def __del__(self, _warn=warnings.warn):
+        threads = [thread for thread in list(self._threads.values())
+                   if thread.is_alive()]
+        if threads:
+            _warn(f"{self.__class__} has registered but not finished child processes",
+                  ResourceWarning,
+                  source=self)
+
+    def add_child_handler(self, pid, callback, *args):
+        loop = events.get_running_loop()
+        thread = threading.Thread(target=self._do_waitpid,
+                                  name=f"waitpid-{next(self._pid_counter)}",
+                                  args=(loop, pid, callback, args),
+                                  daemon=True)
+        self._threads[pid] = thread
+        thread.start()
+
+    def remove_child_handler(self, pid):
+        # asyncio never calls remove_child_handler() !!!
+        # The method is no-op but is implemented because
+        # abstract base classes require it.
+        return True
+
+    def attach_loop(self, loop):
+        pass
+
+    def _do_waitpid(self, loop, expected_pid, callback, args):
+        assert expected_pid > 0
+
+        try:
+            pid, status = os.waitpid(expected_pid, 0)
+        except ChildProcessError:
+            # The child process is already reaped
+            # (may happen if waitpid() is called elsewhere).
+            pid = expected_pid
+            returncode = 255
+            logger.warning(
+                "Unknown child process pid %d, will report returncode 255",
+                pid)
+        else:
+            returncode = _compute_returncode(status)
+            if loop.get_debug():
+                logger.debug('process %s exited with returncode %s',
+                             expected_pid, returncode)
+
+        if loop.is_closed():
+            logger.warning("Loop %r that handles pid %r is closed", loop, pid)
+        else:
+            loop.call_soon_threadsafe(callback, pid, returncode, *args)
+
+        self._threads.pop(expected_pid)
+
+
 class _UnixDefaultEventLoopPolicy(events.BaseDefaultEventLoopPolicy):
     """UNIX event loop policy with a watcher for child processes."""
     _loop_factory = _UnixSelectorEventLoop
@@ -1097,9 +1427,8 @@ class _UnixDefaultEventLoopPolicy(events.BaseDefaultEventLoopPolicy):
     def _init_watcher(self):
         with events._lock:
             if self._watcher is None:  # pragma: no branch
-                self._watcher = SafeChildWatcher()
+                self._watcher = ThreadedChildWatcher()
-                if isinstance(threading.current_thread(),
+                if threading.current_thread() is threading.main_thread():
-                              threading._MainThread):
                     self._watcher.attach_loop(self._local._loop)
 
     def set_event_loop(self, loop):
@@ -1113,13 +1442,13 @@ class _UnixDefaultEventLoopPolicy(events.BaseDefaultEventLoopPolicy):
         super().set_event_loop(loop)
 
         if (self._watcher is not None and
-                isinstance(threading.current_thread(), threading._MainThread)):
+                threading.current_thread() is threading.main_thread()):
             self._watcher.attach_loop(loop)
 
     def get_child_watcher(self):
         """Get the watcher for child processes.
 
-        If not yet set, a SafeChildWatcher object is automatically created.
+        If not yet set, a ThreadedChildWatcher object is automatically created.
         """
         if self._watcher is None:
             self._init_watcher()

extlib/Python/Lib/asyncio/windows_events.py

@@ -1,5 +1,10 @@
 """Selector and proactor event loops for Windows."""
 
+import sys
+
+if sys.platform != 'win32':  # pragma: no cover
+    raise ImportError('win32 only')
+
 import _overlapped
 import _winapi
 import errno
@@ -7,11 +12,13 @@ import math
 import msvcrt
 import socket
 import struct
+import time
 import weakref
 
 from . import events
 from . import base_subprocess
 from . import futures
+from . import exceptions
 from . import proactor_events
 from . import selector_events
 from . import tasks
@@ -73,9 +80,9 @@ class _OverlappedFuture(futures.Future):
             self._loop.call_exception_handler(context)
         self._ov = None
 
-    def cancel(self):
+    def cancel(self, msg=None):
         self._cancel_overlapped()
-        return super().cancel()
+        return super().cancel(msg=msg)
 
     def set_exception(self, exception):
         super().set_exception(exception)
@@ -147,9 +154,9 @@ class _BaseWaitHandleFuture(futures.Future):
 
         self._unregister_wait_cb(None)
 
-    def cancel(self):
+    def cancel(self, msg=None):
         self._unregister_wait()
-        return super().cancel()
+        return super().cancel(msg=msg)
 
     def set_exception(self, exception):
         self._unregister_wait()
@@ -307,6 +314,25 @@ class ProactorEventLoop(proactor_events.BaseProactorEventLoop):
             proactor = IocpProactor()
         super().__init__(proactor)
 
+    def run_forever(self):
+        try:
+            assert self._self_reading_future is None
+            self.call_soon(self._loop_self_reading)
+            super().run_forever()
+        finally:
+            if self._self_reading_future is not None:
+                ov = self._self_reading_future._ov
+                self._self_reading_future.cancel()
+                # self_reading_future was just cancelled so if it hasn't been
+                # finished yet, it never will be (it's possible that it has
+                # already finished and its callback is waiting in the queue,
+                # where it could still happen if the event loop is restarted).
+                # Unregister it otherwise IocpProactor.close will wait for it
+                # forever
+                if ov is not None:
+                    self._proactor._unregister(ov)
+                self._self_reading_future = None
+
     async def create_pipe_connection(self, protocol_factory, address):
         f = self._proactor.connect_pipe(address)
         pipe = await f
@@ -351,7 +377,7 @@ class ProactorEventLoop(proactor_events.BaseProactorEventLoop):
                 elif self._debug:
                     logger.warning("Accept pipe failed on pipe %r",
                                    pipe, exc_info=True)
-            except futures.CancelledError:
+            except exceptions.CancelledError:
                 if pipe:
                     pipe.close()
             else:
@@ -371,7 +397,9 @@ class ProactorEventLoop(proactor_events.BaseProactorEventLoop):
                                              **kwargs)
         try:
             await waiter
-        except Exception:
+        except (SystemExit, KeyboardInterrupt):
+            raise
+        except BaseException:
             transp.close()
             await transp._wait()
             raise
@@ -392,10 +420,16 @@ class IocpProactor:
         self._unregistered = []
         self._stopped_serving = weakref.WeakSet()
 
+    def _check_closed(self):
+        if self._iocp is None:
+            raise RuntimeError('IocpProactor is closed')
+
     def __repr__(self):
-        return ('<%s overlapped#=%s result#=%s>'
+        info = ['overlapped#=%s' % len(self._cache),
-                % (self.__class__.__name__, len(self._cache),
+                'result#=%s' % len(self._results)]
-                   len(self._results)))
+        if self._iocp is None:
+            info.append('closed')
+        return '<%s %s>' % (self.__class__.__name__, " ".join(info))
 
     def set_loop(self, loop):
         self._loop = loop
@@ -444,7 +478,7 @@ class IocpProactor:
             else:
                 ov.ReadFileInto(conn.fileno(), buf)
         except BrokenPipeError:
-            return self._result(b'')
+            return self._result(0)
 
         def finish_recv(trans, key, ov):
             try:
@@ -458,6 +492,44 @@ class IocpProactor:
 
         return self._register(ov, conn, finish_recv)
 
+    def recvfrom(self, conn, nbytes, flags=0):
+        self._register_with_iocp(conn)
+        ov = _overlapped.Overlapped(NULL)
+        try:
+            ov.WSARecvFrom(conn.fileno(), nbytes, flags)
+        except BrokenPipeError:
+            return self._result((b'', None))
+
+        def finish_recv(trans, key, ov):
+            try:
+                return ov.getresult()
+            except OSError as exc:
+                if exc.winerror in (_overlapped.ERROR_NETNAME_DELETED,
+                                    _overlapped.ERROR_OPERATION_ABORTED):
+                    raise ConnectionResetError(*exc.args)
+                else:
+                    raise
+
+        return self._register(ov, conn, finish_recv)
+
+    def sendto(self, conn, buf, flags=0, addr=None):
+        self._register_with_iocp(conn)
+        ov = _overlapped.Overlapped(NULL)
+
+        ov.WSASendTo(conn.fileno(), buf, flags, addr)
+
+        def finish_send(trans, key, ov):
+            try:
+                return ov.getresult()
+            except OSError as exc:
+                if exc.winerror in (_overlapped.ERROR_NETNAME_DELETED,
+                                    _overlapped.ERROR_OPERATION_ABORTED):
+                    raise ConnectionResetError(*exc.args)
+                else:
+                    raise
+
+        return self._register(ov, conn, finish_send)
+
     def send(self, conn, buf, flags=0):
         self._register_with_iocp(conn)
         ov = _overlapped.Overlapped(NULL)
@@ -497,7 +569,7 @@ class IocpProactor:
             # Coroutine closing the accept socket if the future is cancelled
             try:
                 await future
-            except futures.CancelledError:
+            except exceptions.CancelledError:
                 conn.close()
                 raise
 
@@ -507,6 +579,14 @@ class IocpProactor:
         return future
 
     def connect(self, conn, address):
+        if conn.type == socket.SOCK_DGRAM:
+            # WSAConnect will complete immediately for UDP sockets so we don't
+            # need to register any IOCP operation
+            _overlapped.WSAConnect(conn.fileno(), address)
+            fut = self._loop.create_future()
+            fut.set_result(None)
+            return fut
+
         self._register_with_iocp(conn)
         # The socket needs to be locally bound before we call ConnectEx().
         try:
@@ -582,7 +662,7 @@ class IocpProactor:
 
             # ConnectPipe() failed with ERROR_PIPE_BUSY: retry later
             delay = min(delay * 2, CONNECT_PIPE_MAX_DELAY)
-            await tasks.sleep(delay, loop=self._loop)
+            await tasks.sleep(delay)
 
         return windows_utils.PipeHandle(handle)
 
@@ -602,6 +682,8 @@ class IocpProactor:
         return fut
 
     def _wait_for_handle(self, handle, timeout, _is_cancel):
+        self._check_closed()
+
         if timeout is None:
             ms = _winapi.INFINITE
         else:
@@ -644,6 +726,8 @@ class IocpProactor:
             # that succeed immediately.
 
     def _register(self, ov, obj, callback):
+        self._check_closed()
+
         # Return a future which will be set with the result of the
         # operation when it completes.  The future's value is actually
         # the value returned by callback().
@@ -680,6 +764,7 @@ class IocpProactor:
         already be signalled (pending in the proactor event queue). It is also
         safe if the event is never signalled (because it was cancelled).
         """
+        self._check_closed()
         self._unregistered.append(ov)
 
     def _get_accept_socket(self, family):
@@ -749,6 +834,10 @@ class IocpProactor:
         self._stopped_serving.add(obj)
 
     def close(self):
+        if self._iocp is None:
+            # already closed
+            return
+
         # Cancel remaining registered operations.
         for address, (fut, ov, obj, callback) in list(self._cache.items()):
             if fut.cancelled():
@@ -771,14 +860,25 @@ class IocpProactor:
                             context['source_traceback'] = fut._source_traceback
                         self._loop.call_exception_handler(context)
 
+        # Wait until all cancelled overlapped complete: don't exit with running
+        # overlapped to prevent a crash. Display progress every second if the
+        # loop is still running.
+        msg_update = 1.0
+        start_time = time.monotonic()
+        next_msg = start_time + msg_update
         while self._cache:
-            if not self._poll(1):
+            if next_msg <= time.monotonic():
-                logger.debug('taking long time to close proactor')
+                logger.debug('%r is running after closing for %.1f seconds',
+                             self, time.monotonic() - start_time)
+                next_msg = time.monotonic() + msg_update
+
+            # handle a few events, or timeout
+            self._poll(msg_update)
 
         self._results = []
-        if self._iocp is not None:
+
-            _winapi.CloseHandle(self._iocp)
+        _winapi.CloseHandle(self._iocp)
-            self._iocp = None
+        self._iocp = None
 
     def __del__(self):
         self.close()
@@ -810,4 +910,4 @@ class WindowsProactorEventLoopPolicy(events.BaseDefaultEventLoopPolicy):
     _loop_factory = ProactorEventLoop
 
 
-DefaultEventLoopPolicy = WindowsSelectorEventLoopPolicy
+DefaultEventLoopPolicy = WindowsProactorEventLoopPolicy

extlib/Python/Lib/asyncio/windows_utils.py

@@ -107,10 +107,9 @@ class PipeHandle:
             CloseHandle(self._handle)
             self._handle = None
 
-    def __del__(self):
+    def __del__(self, _warn=warnings.warn):
         if self._handle is not None:
-            warnings.warn(f"unclosed {self!r}", ResourceWarning,
+            _warn(f"unclosed {self!r}", ResourceWarning, source=self)
-                          source=self)
             self.close()
 
     def __enter__(self):

extlib/Python/Lib/asyncore.py

@@ -228,7 +228,7 @@ class dispatcher:
         if sock:
             # Set to nonblocking just to make sure for cases where we
             # get a socket from a blocking source.
-            sock.setblocking(0)
+            sock.setblocking(False)
             self.set_socket(sock, map)
             self.connected = True
             # The constructor no longer requires that the socket
@@ -262,8 +262,6 @@ class dispatcher:
                 status.append(repr(self.addr))
         return '<%s at %#x>' % (' '.join(status), id(self))
 
-    __str__ = __repr__
-
     def add_channel(self, map=None):
         #self.log_info('adding channel %s' % self)
         if map is None:
@@ -282,7 +280,7 @@ class dispatcher:
     def create_socket(self, family=socket.AF_INET, type=socket.SOCK_STREAM):
         self.family_and_type = family, type
         sock = socket.socket(family, type)
-        sock.setblocking(0)
+        sock.setblocking(False)
         self.set_socket(sock)
 
     def set_socket(self, sock, map=None):

extlib/Python/Lib/base64.py

@@ -82,7 +82,7 @@ def b64decode(s, altchars=None, validate=False):
         altchars = _bytes_from_decode_data(altchars)
         assert len(altchars) == 2, repr(altchars)
         s = s.translate(bytes.maketrans(altchars, b'+/'))
-    if validate and not re.match(b'^[A-Za-z0-9+/]*={0,2}$', s):
+    if validate and not re.fullmatch(b'[A-Za-z0-9+/]*={0,2}', s):
         raise binascii.Error('Non-base64 digit found')
     return binascii.a2b_base64(s)
 
@@ -231,23 +231,16 @@ def b32decode(s, casefold=False, map01=None):
             raise binascii.Error('Non-base32 digit found') from None
         decoded += acc.to_bytes(5, 'big')
     # Process the last, partial quanta
-    if padchars:
+    if l % 8 or padchars not in {0, 1, 3, 4, 6}:
+        raise binascii.Error('Incorrect padding')
+    if padchars and decoded:
         acc <<= 5 * padchars
         last = acc.to_bytes(5, 'big')
-        if padchars == 1:
+        leftover = (43 - 5 * padchars) // 8  # 1: 4, 3: 3, 4: 2, 6: 1
-            decoded[-5:] = last[:-1]
+        decoded[-5:] = last[:leftover]
-        elif padchars == 3:
-            decoded[-5:] = last[:-2]
-        elif padchars == 4:
-            decoded[-5:] = last[:-3]
-        elif padchars == 6:
-            decoded[-5:] = last[:-4]
-        else:
-            raise binascii.Error('Incorrect padding')
     return bytes(decoded)
 
 
-
 # RFC 3548, Base 16 Alphabet specifies uppercase, but hexlify() returns
 # lowercase.  The RFC also recommends against accepting input case
 # insensitively.
@@ -327,7 +320,7 @@ def a85encode(b, *, foldspaces=False, wrapcol=0, pad=False, adobe=False):
     global _a85chars, _a85chars2
     # Delay the initialization of tables to not waste memory
     # if the function is never called
-    if _a85chars is None:
+    if _a85chars2 is None:
         _a85chars = [bytes((i,)) for i in range(33, 118)]
         _a85chars2 = [(a + b) for a in _a85chars for b in _a85chars]
 
@@ -435,7 +428,7 @@ def b85encode(b, pad=False):
     global _b85chars, _b85chars2
     # Delay the initialization of tables to not waste memory
     # if the function is never called
-    if _b85chars is None:
+    if _b85chars2 is None:
         _b85chars = [bytes((i,)) for i in _b85alphabet]
         _b85chars2 = [(a + b) for a in _b85chars for b in _b85chars]
     return _85encode(b, _b85chars, _b85chars2, pad)
@@ -538,28 +531,12 @@ def encodebytes(s):
         pieces.append(binascii.b2a_base64(chunk))
     return b"".join(pieces)
 
-def encodestring(s):
-    """Legacy alias of encodebytes()."""
-    import warnings
-    warnings.warn("encodestring() is a deprecated alias since 3.1, "
-                  "use encodebytes()",
-                  DeprecationWarning, 2)
-    return encodebytes(s)
-
 
 def decodebytes(s):
     """Decode a bytestring of base-64 data into a bytes object."""
     _input_type_check(s)
     return binascii.a2b_base64(s)
 
-def decodestring(s):
-    """Legacy alias of decodebytes()."""
-    import warnings
-    warnings.warn("decodestring() is a deprecated alias since Python 3.1, "
-                  "use decodebytes()",
-                  DeprecationWarning, 2)
-    return decodebytes(s)
-
 
 # Usable as a script...
 def main():

extlib/Python/Lib/bdb.py

@@ -38,7 +38,7 @@ class Bdb:
         """Return canonical form of filename.
 
         For real filenames, the canonical form is a case-normalized (on
-        case insenstive filesystems) absolute path.  'Filenames' with
+        case insensitive filesystems) absolute path.  'Filenames' with
         angle brackets, such as "<stdin>", generated in interactive
         mode, are returned unchanged.
         """
@@ -74,7 +74,7 @@ class Bdb:
             return: A function or other code block is about to return.
             exception: An exception has occurred.
             c_call: A C function is about to be called.
-            c_return: A C functon has returned.
+            c_return: A C function has returned.
             c_exception: A C function has raised an exception.
 
         For the Python events, specialized functions (see the dispatch_*()
@@ -117,7 +117,7 @@ class Bdb:
         """Invoke user function and return trace function for call event.
 
         If the debugger stops on this function call, invoke
-        self.user_call(). Raise BbdQuit if self.quitting is set.
+        self.user_call(). Raise BdbQuit if self.quitting is set.
         Return self.trace_dispatch to continue tracing in this scope.
         """
         # XXX 'arg' is no longer used
@@ -190,6 +190,8 @@ class Bdb:
 
     def is_skipped_module(self, module_name):
         "Return True if module_name matches any skip pattern."
+        if module_name is None:  # some modules do not have names
+            return False
         for pattern in self.skip:
             if fnmatch.fnmatch(module_name, pattern):
                 return True
@@ -382,7 +384,7 @@ class Bdb:
         return None
 
     def _prune_breaks(self, filename, lineno):
-        """Prune breakpoints for filname:lineno.
+        """Prune breakpoints for filename:lineno.
 
         A list of breakpoints is maintained in the Bdb instance and in
         the Breakpoint class.  If a breakpoint in the Bdb instance no
@@ -546,14 +548,7 @@ class Bdb:
             s += frame.f_code.co_name
         else:
             s += "<lambda>"
-        if '__args__' in frame.f_locals:
+        s += '()'
-            args = frame.f_locals['__args__']
-        else:
-            args = None
-        if args:
-            s += reprlib.repr(args)
-        else:
-            s += '()'
         if '__return__' in frame.f_locals:
             rv = frame.f_locals['__return__']
             s += '->'
@@ -616,7 +611,7 @@ class Bdb:
 
     # This method is more useful to debug a single function call.
 
-    def runcall(self, func, *args, **kwds):
+    def runcall(self, func, /, *args, **kwds):
         """Debug a single function call.
 
         Return the result of the function call.

extlib/Python/Lib/binhex.py

@@ -21,10 +21,16 @@ hexbin(inputfilename, outputfilename)
 # input. The resulting code (xx 90 90) would appear to be interpreted as an
 # escaped *value* of 0x90. All coders I've seen appear to ignore this nicety...
 #
+import binascii
+import contextlib
 import io
 import os
 import struct
-import binascii
+import warnings
+
+warnings.warn('the binhex module is deprecated', DeprecationWarning,
+              stacklevel=2)
+
 
 __all__ = ["binhex","hexbin","Error"]
 
@@ -76,6 +82,16 @@ class openrsrc:
     def close(self):
         pass
 
+
+# DeprecationWarning is already emitted on "import binhex". There is no need
+# to repeat the warning at each call to deprecated binascii functions.
+@contextlib.contextmanager
+def _ignore_deprecation_warning():
+    with warnings.catch_warnings():
+        warnings.filterwarnings('ignore', '', DeprecationWarning)
+        yield
+
+
 class _Hqxcoderengine:
     """Write data to the coder in 3-byte chunks"""
 
@@ -93,23 +109,25 @@ class _Hqxcoderengine:
         self.data = self.data[todo:]
         if not data:
             return
-        self.hqxdata = self.hqxdata + binascii.b2a_hqx(data)
+        with _ignore_deprecation_warning():
+            self.hqxdata = self.hqxdata + binascii.b2a_hqx(data)
         self._flush(0)
 
     def _flush(self, force):
         first = 0
         while first <= len(self.hqxdata) - self.linelen:
             last = first + self.linelen
-            self.ofp.write(self.hqxdata[first:last] + b'\n')
+            self.ofp.write(self.hqxdata[first:last] + b'\r')
             self.linelen = LINELEN
             first = last
         self.hqxdata = self.hqxdata[first:]
         if force:
-            self.ofp.write(self.hqxdata + b':\n')
+            self.ofp.write(self.hqxdata + b':\r')
 
     def close(self):
         if self.data:
-            self.hqxdata = self.hqxdata + binascii.b2a_hqx(self.data)
+            with _ignore_deprecation_warning():
+                self.hqxdata = self.hqxdata + binascii.b2a_hqx(self.data)
         self._flush(1)
         self.ofp.close()
         del self.ofp
@@ -125,13 +143,15 @@ class _Rlecoderengine:
         self.data = self.data + data
         if len(self.data) < REASONABLY_LARGE:
             return
-        rledata = binascii.rlecode_hqx(self.data)
+        with _ignore_deprecation_warning():
+            rledata = binascii.rlecode_hqx(self.data)
         self.ofp.write(rledata)
         self.data = b''
 
     def close(self):
         if self.data:
-            rledata = binascii.rlecode_hqx(self.data)
+            with _ignore_deprecation_warning():
+                rledata = binascii.rlecode_hqx(self.data)
             self.ofp.write(rledata)
         self.ofp.close()
         del self.ofp
@@ -276,7 +296,8 @@ class _Hqxdecoderengine:
             #
             while True:
                 try:
-                    decdatacur, self.eof = binascii.a2b_hqx(data)
+                    with _ignore_deprecation_warning():
+                        decdatacur, self.eof = binascii.a2b_hqx(data)
                     break
                 except binascii.Incomplete:
                     pass
@@ -312,8 +333,9 @@ class _Rledecoderengine:
     def _fill(self, wtd):
         self.pre_buffer = self.pre_buffer + self.ifp.read(wtd + 4)
         if self.ifp.eof:
-            self.post_buffer = self.post_buffer + \
+            with _ignore_deprecation_warning():
-                binascii.rledecode_hqx(self.pre_buffer)
+                self.post_buffer = self.post_buffer + \
+                    binascii.rledecode_hqx(self.pre_buffer)
             self.pre_buffer = b''
             return
 
@@ -340,8 +362,9 @@ class _Rledecoderengine:
         else:
             mark = mark - 1
 
-        self.post_buffer = self.post_buffer + \
+        with _ignore_deprecation_warning():
-            binascii.rledecode_hqx(self.pre_buffer[:mark])
+            self.post_buffer = self.post_buffer + \
+                binascii.rledecode_hqx(self.pre_buffer[:mark])
         self.pre_buffer = self.pre_buffer[mark:]
 
     def close(self):

extlib/Python/Lib/bisect.py

@@ -9,14 +9,7 @@ def insort_right(a, x, lo=0, hi=None):
     slice of a to be searched.
     """
 
-    if lo < 0:
+    lo = bisect_right(a, x, lo, hi)
-        raise ValueError('lo must be non-negative')
-    if hi is None:
-        hi = len(a)
-    while lo < hi:
-        mid = (lo+hi)//2
-        if x < a[mid]: hi = mid
-        else: lo = mid+1
     a.insert(lo, x)
 
 def bisect_right(a, x, lo=0, hi=None):
@@ -36,6 +29,7 @@ def bisect_right(a, x, lo=0, hi=None):
         hi = len(a)
     while lo < hi:
         mid = (lo+hi)//2
+        # Use __lt__ to match the logic in list.sort() and in heapq
         if x < a[mid]: hi = mid
         else: lo = mid+1
     return lo
@@ -49,14 +43,7 @@ def insort_left(a, x, lo=0, hi=None):
     slice of a to be searched.
     """
 
-    if lo < 0:
+    lo = bisect_left(a, x, lo, hi)
-        raise ValueError('lo must be non-negative')
-    if hi is None:
-        hi = len(a)
-    while lo < hi:
-        mid = (lo+hi)//2
-        if a[mid] < x: lo = mid+1
-        else: hi = mid
     a.insert(lo, x)
 
 
@@ -77,6 +64,7 @@ def bisect_left(a, x, lo=0, hi=None):
         hi = len(a)
     while lo < hi:
         mid = (lo+hi)//2
+        # Use __lt__ to match the logic in list.sort() and in heapq
         if a[mid] < x: lo = mid+1
         else: hi = mid
     return lo

extlib/Python/Lib/bz2.py

@@ -12,7 +12,6 @@ __author__ = "Nadeem Vawda <nadeem.vawda@gmail.com>"
 from builtins import open as _builtin_open
 import io
 import os
-import warnings
 import _compression
 from threading import RLock
 
@@ -36,7 +35,7 @@ class BZ2File(_compression.BaseStream):
     returned as bytes, and data to be written should be given as bytes.
     """
 
-    def __init__(self, filename, mode="r", buffering=None, compresslevel=9):
+    def __init__(self, filename, mode="r", *, compresslevel=9):
         """Open a bzip2-compressed file.
 
         If filename is a str, bytes, or PathLike object, it gives the
@@ -47,8 +46,6 @@ class BZ2File(_compression.BaseStream):
         'x' for creating exclusively, or 'a' for appending. These can
         equivalently be given as 'rb', 'wb', 'xb', and 'ab'.
 
-        buffering is ignored. Its use is deprecated.
-
         If mode is 'w', 'x' or 'a', compresslevel can be a number between 1
         and 9 specifying the level of compression: 1 produces the least
         compression, and 9 (default) produces the most compression.
@@ -63,10 +60,6 @@ class BZ2File(_compression.BaseStream):
         self._closefp = False
         self._mode = _MODE_CLOSED
 
-        if buffering is not None:
-            warnings.warn("Use of 'buffering' argument is deprecated",
-                          DeprecationWarning)
-
         if not (1 <= compresslevel <= 9):
             raise ValueError("compresslevel must be between 1 and 9")
 
@@ -233,15 +226,23 @@ class BZ2File(_compression.BaseStream):
         """Write a byte string to the file.
 
         Returns the number of uncompressed bytes written, which is
-        always len(data). Note that due to buffering, the file on disk
+        always the length of data in bytes. Note that due to buffering,
-        may not reflect the data written until close() is called.
+        the file on disk may not reflect the data written until close()
+        is called.
         """
         with self._lock:
             self._check_can_write()
+            if isinstance(data, (bytes, bytearray)):
+                length = len(data)
+            else:
+                # accept any data that supports the buffer protocol
+                data = memoryview(data)
+                length = data.nbytes
+
             compressed = self._compressor.compress(data)
             self._fp.write(compressed)
-            self._pos += len(data)
+            self._pos += length
-            return len(data)
+            return length
 
     def writelines(self, seq):
         """Write a sequence of byte strings to the file.

extlib/Python/Lib/cProfile.py

@@ -7,6 +7,7 @@
 __all__ = ["run", "runctx", "Profile"]
 
 import _lsprof
+import io
 import profile as _pyprofile
 
 # ____________________________________________________________
@@ -25,11 +26,11 @@ runctx.__doc__ = _pyprofile.runctx.__doc__
 # ____________________________________________________________
 
 class Profile(_lsprof.Profiler):
-    """Profile(custom_timer=None, time_unit=None, subcalls=True, builtins=True)
+    """Profile(timer=None, timeunit=None, subcalls=True, builtins=True)
 
     Builds a profiler object using the specified timer function.
     The default timer is a fast built-in one based on real time.
-    For custom timer functions returning integers, time_unit can
+    For custom timer functions returning integers, timeunit can
     be a float specifying a scale (i.e. how long each integer unit
     is, in seconds).
     """
@@ -103,13 +104,20 @@ class Profile(_lsprof.Profiler):
         return self
 
     # This method is more useful to profile a single function call.
-    def runcall(self, func, *args, **kw):
+    def runcall(self, func, /, *args, **kw):
         self.enable()
         try:
             return func(*args, **kw)
         finally:
             self.disable()
 
+    def __enter__(self):
+        self.enable()
+        return self
+
+    def __exit__(self, *exc_info):
+        self.disable()
+
 # ____________________________________________________________
 
 def label(code):
@@ -124,6 +132,7 @@ def main():
     import os
     import sys
     import runpy
+    import pstats
     from optparse import OptionParser
     usage = "cProfile.py [-o output_file_path] [-s sort] [-m module | scriptfile] [arg] ..."
     parser = OptionParser(usage=usage)
@@ -132,7 +141,8 @@ def main():
         help="Save stats to <outfile>", default=None)
     parser.add_option('-s', '--sort', dest="sort",
         help="Sort order when printing to stdout, based on pstats.Stats class",
-        default=-1)
+        default=-1,
+        choices=sorted(pstats.Stats.sort_arg_dict_default))
     parser.add_option('-m', dest="module", action="store_true",
         help="Profile a library module", default=False)
 
@@ -143,6 +153,11 @@ def main():
     (options, args) = parser.parse_args()
     sys.argv[:] = args
 
+    # The script that we're profiling may chdir, so capture the absolute path
+    # to the output file at startup.
+    if options.outfile is not None:
+        options.outfile = os.path.abspath(options.outfile)
+
     if len(args) > 0:
         if options.module:
             code = "run_module(modname, run_name='__main__')"
@@ -153,7 +168,7 @@ def main():
         else:
             progname = args[0]
             sys.path.insert(0, os.path.dirname(progname))
-            with open(progname, 'rb') as fp:
+            with io.open_code(progname) as fp:
                 code = compile(fp.read(), progname, 'exec')
             globs = {
                 '__file__': progname,
@@ -161,7 +176,12 @@ def main():
                 '__package__': None,
                 '__cached__': None,
             }
-        runctx(code, globs, None, options.outfile, options.sort)
+        try:
+            runctx(code, globs, None, options.outfile, options.sort)
+        except BrokenPipeError as exc:
+            # Prevent "Exception ignored" during interpreter shutdown.
+            sys.stdout = None
+            sys.exit(exc.errno)
     else:
         parser.print_usage()
     return parser

extlib/Python/Lib/calendar.py

@@ -127,18 +127,18 @@ def monthrange(year, month):
     return day1, ndays
 
 
-def monthlen(year, month):
+def _monthlen(year, month):
     return mdays[month] + (month == February and isleap(year))
 
 
-def prevmonth(year, month):
+def _prevmonth(year, month):
     if month == 1:
         return year-1, 12
     else:
         return year, month-1
 
 
-def nextmonth(year, month):
+def _nextmonth(year, month):
     if month == 12:
         return year+1, 1
     else:
@@ -207,13 +207,13 @@ class Calendar(object):
         day1, ndays = monthrange(year, month)
         days_before = (day1 - self.firstweekday) % 7
         days_after = (self.firstweekday - day1 - ndays) % 7
-        y, m = prevmonth(year, month)
+        y, m = _prevmonth(year, month)
-        end = monthlen(y, m) + 1
+        end = _monthlen(y, m) + 1
         for d in range(end-days_before, end):
             yield y, m, d
         for d in range(1, ndays + 1):
             yield year, month, d
-        y, m = nextmonth(year, month)
+        y, m = _nextmonth(year, month)
         for d in range(1, days_after + 1):
             yield y, m, d
 

extlib/Python/Lib/cgi.py

@@ -38,16 +38,14 @@ import os
 import urllib.parse
 from email.parser import FeedParser
 from email.message import Message
-from warnings import warn
 import html
 import locale
 import tempfile
 
-__all__ = ["MiniFieldStorage", "FieldStorage",
+__all__ = ["MiniFieldStorage", "FieldStorage", "parse", "parse_multipart",
-           "parse", "parse_qs", "parse_qsl", "parse_multipart",
            "parse_header", "test", "print_exception", "print_environ",
            "print_form", "print_directory", "print_arguments",
-           "print_environ_usage", "escape"]
+           "print_environ_usage"]
 
 # Logging support
 # ===============
@@ -117,7 +115,8 @@ log = initlog           # The current logging function
 # 0 ==> unlimited input
 maxlen = 0
 
-def parse(fp=None, environ=os.environ, keep_blank_values=0, strict_parsing=0):
+def parse(fp=None, environ=os.environ, keep_blank_values=0,
+          strict_parsing=0, separator='&'):
     """Parse a query in the environment or from a file (default stdin)
 
         Arguments, all optional:
@@ -136,6 +135,9 @@ def parse(fp=None, environ=os.environ, keep_blank_values=0, strict_parsing=0):
         strict_parsing: flag indicating what to do with parsing errors.
             If false (the default), errors are silently ignored.
             If true, errors raise a ValueError exception.
+
+        separator: str. The symbol to use for separating the query arguments.
+            Defaults to &.
     """
     if fp is None:
         fp = sys.stdin
@@ -156,7 +158,7 @@ def parse(fp=None, environ=os.environ, keep_blank_values=0, strict_parsing=0):
     if environ['REQUEST_METHOD'] == 'POST':
         ctype, pdict = parse_header(environ['CONTENT_TYPE'])
         if ctype == 'multipart/form-data':
-            return parse_multipart(fp, pdict)
+            return parse_multipart(fp, pdict, separator=separator)
         elif ctype == 'application/x-www-form-urlencoded':
             clength = int(environ['CONTENT_LENGTH'])
             if maxlen and clength > maxlen:
@@ -180,25 +182,10 @@ def parse(fp=None, environ=os.environ, keep_blank_values=0, strict_parsing=0):
             qs = ""
         environ['QUERY_STRING'] = qs    # XXX Shouldn't, really
     return urllib.parse.parse_qs(qs, keep_blank_values, strict_parsing,
-                                 encoding=encoding)
+                                 encoding=encoding, separator=separator)
 
 
-# parse query string function called from urlparse,
+def parse_multipart(fp, pdict, encoding="utf-8", errors="replace", separator='&'):
-# this is done in order to maintain backward compatibility.
-
-def parse_qs(qs, keep_blank_values=0, strict_parsing=0):
-    """Parse a query given as a string argument."""
-    warn("cgi.parse_qs is deprecated, use urllib.parse.parse_qs instead",
-         DeprecationWarning, 2)
-    return urllib.parse.parse_qs(qs, keep_blank_values, strict_parsing)
-
-def parse_qsl(qs, keep_blank_values=0, strict_parsing=0):
-    """Parse a query given as a string argument."""
-    warn("cgi.parse_qsl is deprecated, use urllib.parse.parse_qsl instead",
-         DeprecationWarning, 2)
-    return urllib.parse.parse_qsl(qs, keep_blank_values, strict_parsing)
-
-def parse_multipart(fp, pdict, encoding="utf-8", errors="replace"):
     """Parse multipart input.
 
     Arguments:
@@ -217,9 +204,12 @@ def parse_multipart(fp, pdict, encoding="utf-8", errors="replace"):
     ctype = "multipart/form-data; boundary={}".format(boundary)
     headers = Message()
     headers.set_type(ctype)
-    headers['Content-Length'] = pdict['CONTENT-LENGTH']
+    try:
+        headers['Content-Length'] = pdict['CONTENT-LENGTH']
+    except KeyError:
+        pass
     fs = FieldStorage(fp, headers=headers, encoding=encoding, errors=errors,
-        environ={'REQUEST_METHOD': 'POST'})
+        environ={'REQUEST_METHOD': 'POST'}, separator=separator)
     return {k: fs.getlist(k) for k in fs}
 
 def _parseparam(s):
@@ -328,7 +318,8 @@ class FieldStorage:
     """
     def __init__(self, fp=None, headers=None, outerboundary=b'',
                  environ=os.environ, keep_blank_values=0, strict_parsing=0,
-                 limit=None, encoding='utf-8', errors='replace'):
+                 limit=None, encoding='utf-8', errors='replace',
+                 max_num_fields=None, separator='&'):
         """Constructor.  Read multipart/* until last part.
 
         Arguments, all optional:
@@ -368,10 +359,15 @@ class FieldStorage:
             for the page sending the form (content-type : meta http-equiv or
             header)
 
+        max_num_fields: int. If set, then __init__ throws a ValueError
+            if there are more than n fields read by parse_qsl().
+
         """
         method = 'GET'
         self.keep_blank_values = keep_blank_values
         self.strict_parsing = strict_parsing
+        self.max_num_fields = max_num_fields
+        self.separator = separator
         if 'REQUEST_METHOD' in environ:
             method = environ['REQUEST_METHOD'].upper()
         self.qs_on_post = None
@@ -473,7 +469,7 @@ class FieldStorage:
             if maxlen and clen > maxlen:
                 raise ValueError('Maximum content length exceeded')
         self.length = clen
-        if self.limit is None and clen:
+        if self.limit is None and clen >= 0:
             self.limit = clen
 
         self.list = self.file = None
@@ -595,12 +591,11 @@ class FieldStorage:
         qs = qs.decode(self.encoding, self.errors)
         if self.qs_on_post:
             qs += '&' + self.qs_on_post
-        self.list = []
         query = urllib.parse.parse_qsl(
             qs, self.keep_blank_values, self.strict_parsing,
-            encoding=self.encoding, errors=self.errors)
+            encoding=self.encoding, errors=self.errors,
-        for key, value in query:
+            max_num_fields=self.max_num_fields, separator=self.separator)
-            self.list.append(MiniFieldStorage(key, value))
+        self.list = [MiniFieldStorage(key, value) for key, value in query]
         self.skip_lines()
 
     FieldStorageClass = None
@@ -614,9 +609,9 @@ class FieldStorage:
         if self.qs_on_post:
             query = urllib.parse.parse_qsl(
                 self.qs_on_post, self.keep_blank_values, self.strict_parsing,
-                encoding=self.encoding, errors=self.errors)
+                encoding=self.encoding, errors=self.errors,
-            for key, value in query:
+                max_num_fields=self.max_num_fields, separator=self.separator)
-                self.list.append(MiniFieldStorage(key, value))
+            self.list.extend(MiniFieldStorage(key, value) for key, value in query)
 
         klass = self.FieldStorageClass or self.__class__
         first_line = self.fp.readline() # bytes
@@ -631,6 +626,11 @@ class FieldStorage:
             first_line = self.fp.readline()
             self.bytes_read += len(first_line)
 
+        # Propagate max_num_fields into the sub class appropriately
+        max_num_fields = self.max_num_fields
+        if max_num_fields is not None:
+            max_num_fields -= len(self.list)
+
         while True:
             parser = FeedParser()
             hdr_text = b""
@@ -650,9 +650,19 @@ class FieldStorage:
             if 'content-length' in headers:
                 del headers['content-length']
 
+            limit = None if self.limit is None \
+                else self.limit - self.bytes_read
             part = klass(self.fp, headers, ib, environ, keep_blank_values,
-                         strict_parsing,self.limit-self.bytes_read,
+                         strict_parsing, limit,
-                         self.encoding, self.errors)
+                         self.encoding, self.errors, max_num_fields, self.separator)
+
+            if max_num_fields is not None:
+                max_num_fields -= 1
+                if part.list:
+                    max_num_fields -= len(part.list)
+                if max_num_fields < 0:
+                    raise ValueError('Max number of fields exceeded')
+
             self.bytes_read += part.bytes_read
             self.list.append(part)
             if part.done or self.bytes_read >= self.length > 0:
@@ -734,7 +744,8 @@ class FieldStorage:
         last_line_lfend = True
         _read = 0
         while 1:
-            if _read >= self.limit:
+
+            if self.limit is not None and 0 <= self.limit <= _read:
                 break
             line = self.fp.readline(1<<16) # bytes
             self.bytes_read += len(line)
@@ -974,18 +985,6 @@ environment as well.  Here are some common variable names:
 # Utilities
 # =========
 
-def escape(s, quote=None):
-    """Deprecated API."""
-    warn("cgi.escape is deprecated, use html.escape instead",
-         DeprecationWarning, stacklevel=2)
-    s = s.replace("&", "&amp;") # Must be done first!
-    s = s.replace("<", "&lt;")
-    s = s.replace(">", "&gt;")
-    if quote:
-        s = s.replace('"', "&quot;")
-    return s
-
-
 def valid_boundary(s):
     import re
     if isinstance(s, bytes):

extlib/Python/Lib/cgitb.py

@@ -124,8 +124,9 @@ function calls leading up to the error, in the order they occurred.</p>'''
         args, varargs, varkw, locals = inspect.getargvalues(frame)
         call = ''
         if func != '?':
-            call = 'in ' + strong(pydoc.html.escape(func)) + \
+            call = 'in ' + strong(pydoc.html.escape(func))
-                inspect.formatargvalues(args, varargs, varkw, locals,
+            if func != "<module>":
+                call += inspect.formatargvalues(args, varargs, varkw, locals,
                     formatvalue=lambda value: '=' + pydoc.html.repr(value))
 
         highlight = {}
@@ -207,8 +208,9 @@ function calls leading up to the error, in the order they occurred.
         args, varargs, varkw, locals = inspect.getargvalues(frame)
         call = ''
         if func != '?':
-            call = 'in ' + func + \
+            call = 'in ' + func
-                inspect.formatargvalues(args, varargs, varkw, locals,
+            if func != "<module>":
+                call += inspect.formatargvalues(args, varargs, varkw, locals,
                     formatvalue=lambda value: '=' + pydoc.text.repr(value))
 
         highlight = {}

extlib/Python/Lib/code.py

@@ -40,7 +40,7 @@ class InteractiveInterpreter:
 
         Arguments are as for compile_command().
 
-        One several things can happen:
+        One of several things can happen:
 
         1) The input is incorrect; compile_command() raised an
         exception (SyntaxError or OverflowError).  A syntax traceback

extlib/Python/Lib/codecs.py

@@ -386,7 +386,7 @@ class StreamWriter(Codec):
 
     def reset(self):
 
-        """ Flushes and resets the codec buffers used for keeping state.
+        """ Resets the codec buffers used for keeping internal state.
 
             Calling this method should ensure that the data on the
             output is put into a clean state, that allows appending
@@ -620,7 +620,7 @@ class StreamReader(Codec):
 
     def reset(self):
 
-        """ Resets the codec buffers used for keeping state.
+        """ Resets the codec buffers used for keeping internal state.
 
             Note that no stream repositioning should take place.
             This method is primarily intended to be able to recover
@@ -838,7 +838,7 @@ class StreamRecoder:
 
     def writelines(self, list):
 
-        data = ''.join(list)
+        data = b''.join(list)
         data, bytesdecoded = self.decode(data, self.errors)
         return self.writer.write(data)
 
@@ -847,6 +847,12 @@ class StreamRecoder:
         self.reader.reset()
         self.writer.reset()
 
+    def seek(self, offset, whence=0):
+        # Seeks must be propagated to both the readers and writers
+        # as they might need to reset their internal buffers.
+        self.reader.seek(offset, whence)
+        self.writer.seek(offset, whence)
+
     def __getattr__(self, name,
                     getattr=getattr):
 
@@ -862,7 +868,7 @@ class StreamRecoder:
 
 ### Shortcuts
 
-def open(filename, mode='r', encoding=None, errors='strict', buffering=1):
+def open(filename, mode='r', encoding=None, errors='strict', buffering=-1):
 
     """ Open an encoded file using the given mode and return
         a wrapped version providing transparent encoding/decoding.
@@ -883,7 +889,8 @@ def open(filename, mode='r', encoding=None, errors='strict', buffering=1):
         encoding error occurs.
 
         buffering has the same meaning as for the builtin open() API.
-        It defaults to line buffered.
+        It defaults to -1 which means that the default buffer size will
+        be used.
 
         The returned wrapped file object provides an extra attribute
         .encoding which allows querying the used encoding. This
@@ -898,11 +905,16 @@ def open(filename, mode='r', encoding=None, errors='strict', buffering=1):
     file = builtins.open(filename, mode, buffering)
     if encoding is None:
         return file
-    info = lookup(encoding)
+
-    srw = StreamReaderWriter(file, info.streamreader, info.streamwriter, errors)
+    try:
-    # Add attributes to simplify introspection
+        info = lookup(encoding)
-    srw.encoding = encoding
+        srw = StreamReaderWriter(file, info.streamreader, info.streamwriter, errors)
-    return srw
+        # Add attributes to simplify introspection
+        srw.encoding = encoding
+        return srw
+    except:
+        file.close()
+        raise
 
 def EncodedFile(file, data_encoding, file_encoding=None, errors='strict'):
 

extlib/Python/Lib/codeop.py

@@ -57,6 +57,7 @@ Compile():
 """
 
 import __future__
+import warnings
 
 _features = [getattr(__future__, fname)
              for fname in __future__.all_feature_names]
@@ -80,23 +81,31 @@ def _maybe_compile(compiler, source, filename, symbol):
 
     try:
         code = compiler(source, filename, symbol)
-    except SyntaxError as err:
+    except SyntaxError:
         pass
 
-    try:
+    # Catch syntax warnings after the first compile
-        code1 = compiler(source + "\n", filename, symbol)
+    # to emit warnings (SyntaxWarning, DeprecationWarning) at most once.
-    except SyntaxError as e:
+    with warnings.catch_warnings():
-        err1 = e
+        warnings.simplefilter("error")
+
+        try:
+            code1 = compiler(source + "\n", filename, symbol)
+        except SyntaxError as e:
+            err1 = e
+
+        try:
+            code2 = compiler(source + "\n\n", filename, symbol)
+        except SyntaxError as e:
+            err2 = e
 
     try:
-        code2 = compiler(source + "\n\n", filename, symbol)
+        if code:
-    except SyntaxError as e:
+            return code
-        err2 = e
+        if not code1 and repr(err1) == repr(err2):
-
+            raise err1
-    if code:
+    finally:
-        return code
+        err1 = err2 = None
-    if not code1 and repr(err1) == repr(err2):
-        raise err1
 
 def _compile(source, filename, symbol):
     return compile(source, filename, symbol, PyCF_DONT_IMPLY_DEDENT)
@@ -109,7 +118,8 @@ def compile_command(source, filename="<input>", symbol="single"):
     source -- the source string; may contain \n characters
     filename -- optional filename from which source was read; default
                 "<input>"
-    symbol -- optional grammar start symbol; "single" (default) or "eval"
+    symbol -- optional grammar start symbol; "single" (default), "exec"
+              or "eval"
 
     Return value / exceptions raised:
 
@@ -130,7 +140,7 @@ class Compile:
         self.flags = PyCF_DONT_IMPLY_DEDENT
 
     def __call__(self, source, filename, symbol):
-        codeob = compile(source, filename, symbol, self.flags, 1)
+        codeob = compile(source, filename, symbol, self.flags, True)
         for feature in _features:
             if codeob.co_flags & feature.compiler_flag:
                 self.flags |= feature.compiler_flag

extlib/Python/Lib/collections/__init__.py

@@ -14,17 +14,30 @@ list, set, and tuple.
 
 '''
 
-__all__ = ['deque', 'defaultdict', 'namedtuple', 'UserDict', 'UserList',
+__all__ = [
-            'UserString', 'Counter', 'OrderedDict', 'ChainMap']
+    'ChainMap',
+    'Counter',
+    'OrderedDict',
+    'UserDict',
+    'UserList',
+    'UserString',
+    'defaultdict',
+    'deque',
+    'namedtuple',
+]
 
 import _collections_abc
-from operator import itemgetter as _itemgetter, eq as _eq
-from keyword import iskeyword as _iskeyword
-import sys as _sys
 import heapq as _heapq
-from _weakref import proxy as _proxy
+import sys as _sys
-from itertools import repeat as _repeat, chain as _chain, starmap as _starmap
+
+from itertools import chain as _chain
+from itertools import repeat as _repeat
+from itertools import starmap as _starmap
+from keyword import iskeyword as _iskeyword
+from operator import eq as _eq
+from operator import itemgetter as _itemgetter
 from reprlib import recursive_repr as _recursive_repr
+from _weakref import proxy as _proxy
 
 try:
     from _collections import deque
@@ -47,13 +60,14 @@ def __getattr__(name):
         obj = getattr(_collections_abc, name)
         import warnings
         warnings.warn("Using or importing the ABCs from 'collections' instead "
-                      "of from 'collections.abc' is deprecated, "
+                      "of from 'collections.abc' is deprecated since Python 3.3, "
-                      "and in 3.8 it will stop working",
+                      "and in 3.10 it will stop working",
                       DeprecationWarning, stacklevel=2)
         globals()[name] = obj
         return obj
     raise AttributeError(f'module {__name__!r} has no attribute {name!r}')
 
+
 ################################################################################
 ### OrderedDict
 ################################################################################
@@ -93,16 +107,10 @@ class OrderedDict(dict):
     # Individual links are kept alive by the hard reference in self.__map.
     # Those hard references disappear when a key is deleted from an OrderedDict.
 
-    def __init__(*args, **kwds):
+    def __init__(self, other=(), /, **kwds):
         '''Initialize an ordered dictionary.  The signature is the same as
         regular dictionaries.  Keyword argument order is preserved.
         '''
-        if not args:
-            raise TypeError("descriptor '__init__' of 'OrderedDict' object "
-                            "needs an argument")
-        self, *args = args
-        if len(args) > 1:
-            raise TypeError('expected at most 1 arguments, got %d' % len(args))
         try:
             self.__root
         except AttributeError:
@@ -110,7 +118,7 @@ class OrderedDict(dict):
             self.__root = root = _proxy(self.__hardroot)
             root.prev = root.next = root
             self.__map = {}
-        self.__update(*args, **kwds)
+        self.__update(other, **kwds)
 
     def __setitem__(self, key, value,
                     dict_setitem=dict.__setitem__, proxy=_proxy, Link=_Link):
@@ -299,6 +307,24 @@ class OrderedDict(dict):
             return dict.__eq__(self, other) and all(map(_eq, self, other))
         return dict.__eq__(self, other)
 
+    def __ior__(self, other):
+        self.update(other)
+        return self
+
+    def __or__(self, other):
+        if not isinstance(other, dict):
+            return NotImplemented
+        new = self.__class__(self)
+        new.update(other)
+        return new
+
+    def __ror__(self, other):
+        if not isinstance(other, dict):
+            return NotImplemented
+        new = self.__class__(other)
+        new.update(self)
+        return new
+
 
 try:
     from _collections import OrderedDict
@@ -311,7 +337,10 @@ except ImportError:
 ### namedtuple
 ################################################################################
 
-_nt_itemgetters = {}
+try:
+    from _collections import _tuplegetter
+except ImportError:
+    _tuplegetter = lambda index, doc: property(_itemgetter(index), doc=doc)
 
 def namedtuple(typename, field_names, *, rename=False, defaults=None, module=None):
     """Returns a new subclass of tuple with named fields.
@@ -384,18 +413,23 @@ def namedtuple(typename, field_names, *, rename=False, defaults=None, module=Non
     # Variables used in the methods and docstrings
     field_names = tuple(map(_sys.intern, field_names))
     num_fields = len(field_names)
-    arg_list = repr(field_names).replace("'", "")[1:-1]
+    arg_list = ', '.join(field_names)
+    if num_fields == 1:
+        arg_list += ','
     repr_fmt = '(' + ', '.join(f'{name}=%r' for name in field_names) + ')'
     tuple_new = tuple.__new__
-    _len = len
+    _dict, _tuple, _len, _map, _zip = dict, tuple, len, map, zip
 
     # Create all the named tuple methods to be added to the class namespace
 
-    s = f'def __new__(_cls, {arg_list}): return _tuple_new(_cls, ({arg_list}))'
+    namespace = {
-    namespace = {'_tuple_new': tuple_new, '__name__': f'namedtuple_{typename}'}
+        '_tuple_new': tuple_new,
-    # Note: exec() has the side-effect of interning the field names
+        '__builtins__': {},
-    exec(s, namespace)
+        '__name__': f'namedtuple_{typename}',
-    __new__ = namespace['__new__']
+    }
+    code = f'lambda _cls, {arg_list}: _tuple_new(_cls, ({arg_list}))'
+    __new__ = eval(code, namespace)
+    __new__.__name__ = '__new__'
     __new__.__doc__ = f'Create new instance of {typename}({arg_list})'
     if defaults is not None:
         __new__.__defaults__ = defaults
@@ -410,8 +444,8 @@ def namedtuple(typename, field_names, *, rename=False, defaults=None, module=Non
     _make.__func__.__doc__ = (f'Make a new {typename} object from a sequence '
                               'or iterable')
 
-    def _replace(_self, **kwds):
+    def _replace(self, /, **kwds):
-        result = _self._make(map(kwds.pop, field_names, _self))
+        result = self._make(_map(kwds.pop, field_names, self))
         if kwds:
             raise ValueError(f'Got unexpected field names: {list(kwds)!r}')
         return result
@@ -424,17 +458,22 @@ def namedtuple(typename, field_names, *, rename=False, defaults=None, module=Non
         return self.__class__.__name__ + repr_fmt % self
 
     def _asdict(self):
-        'Return a new OrderedDict which maps field names to their values.'
+        'Return a new dict which maps field names to their values.'
-        return OrderedDict(zip(self._fields, self))
+        return _dict(_zip(self._fields, self))
 
     def __getnewargs__(self):
         'Return self as a plain tuple.  Used by copy and pickle.'
-        return tuple(self)
+        return _tuple(self)
 
     # Modify function metadata to help with introspection and debugging
-
+    for method in (
-    for method in (__new__, _make.__func__, _replace,
+        __new__,
-                   __repr__, _asdict, __getnewargs__):
+        _make.__func__,
+        _replace,
+        __repr__,
+        _asdict,
+        __getnewargs__,
+    ):
         method.__qualname__ = f'{typename}.{method.__name__}'
 
     # Build-up the class namespace dictionary
@@ -443,7 +482,7 @@ def namedtuple(typename, field_names, *, rename=False, defaults=None, module=Non
         '__doc__': f'{typename}({arg_list})',
         '__slots__': (),
         '_fields': field_names,
-        '_fields_defaults': field_defaults,
+        '_field_defaults': field_defaults,
         '__new__': __new__,
         '_make': _make,
         '_replace': _replace,
@@ -451,15 +490,9 @@ def namedtuple(typename, field_names, *, rename=False, defaults=None, module=Non
         '_asdict': _asdict,
         '__getnewargs__': __getnewargs__,
     }
-    cache = _nt_itemgetters
     for index, name in enumerate(field_names):
-        try:
+        doc = _sys.intern(f'Alias for field number {index}')
-            itemgetter_object, doc = cache[index]
+        class_namespace[name] = _tuplegetter(index, doc)
-        except KeyError:
-            itemgetter_object = _itemgetter(index)
-            doc = f'Alias for field number {index}'
-            cache[index] = itemgetter_object, doc
-        class_namespace[name] = property(itemgetter_object, doc=doc)
 
     result = type(typename, (tuple,), class_namespace)
 
@@ -545,7 +578,7 @@ class Counter(dict):
     #   http://code.activestate.com/recipes/259174/
     #   Knuth, TAOCP Vol. II section 4.6.3
 
-    def __init__(*args, **kwds):
+    def __init__(self, iterable=None, /, **kwds):
         '''Create a new, empty Counter object.  And if given, count elements
         from an input iterable.  Or, initialize the count from another mapping
         of elements to their counts.
@@ -556,14 +589,8 @@ class Counter(dict):
         >>> c = Counter(a=4, b=2)                   # a new counter from keyword args
 
         '''
-        if not args:
+        super().__init__()
-            raise TypeError("descriptor '__init__' of 'Counter' object "
+        self.update(iterable, **kwds)
-                            "needs an argument")
-        self, *args = args
-        if len(args) > 1:
-            raise TypeError('expected at most 1 arguments, got %d' % len(args))
-        super(Counter, self).__init__()
-        self.update(*args, **kwds)
 
     def __missing__(self, key):
         'The count of elements not in the Counter is zero.'
@@ -574,8 +601,8 @@ class Counter(dict):
         '''List the n most common elements and their counts from the most
         common to the least.  If n is None, then list all element counts.
 
-        >>> Counter('abcdeabcdabcaba').most_common(3)
+        >>> Counter('abracadabra').most_common(3)
-        [('a', 5), ('b', 4), ('c', 3)]
+        [('a', 5), ('b', 2), ('r', 2)]
 
         '''
         # Emulate Bag.sortedByCount from Smalltalk
@@ -609,12 +636,17 @@ class Counter(dict):
 
     @classmethod
     def fromkeys(cls, iterable, v=None):
-        # There is no equivalent method for counters because setting v=1
+        # There is no equivalent method for counters because the semantics
-        # means that no element can have a count greater than one.
+        # would be ambiguous in cases such as Counter.fromkeys('aaabbc', v=2).
+        # Initializing counters to zero values isn't necessary because zero
+        # is already the default value for counter lookups.  Initializing
+        # to one is easily accomplished with Counter(set(iterable)).  For
+        # more exotic cases, create a dictionary first using a dictionary
+        # comprehension or dict.fromkeys().
         raise NotImplementedError(
             'Counter.fromkeys() is undefined.  Use Counter(iterable) instead.')
 
-    def update(*args, **kwds):
+    def update(self, iterable=None, /, **kwds):
         '''Like dict.update() but add counts instead of replacing them.
 
         Source can be an iterable, a dictionary, or another Counter instance.
@@ -634,13 +666,6 @@ class Counter(dict):
         # contexts.  Instead, we implement straight-addition.  Both the inputs
         # and outputs are allowed to contain zero and negative counts.
 
-        if not args:
-            raise TypeError("descriptor 'update' of 'Counter' object "
-                            "needs an argument")
-        self, *args = args
-        if len(args) > 1:
-            raise TypeError('expected at most 1 arguments, got %d' % len(args))
-        iterable = args[0] if args else None
         if iterable is not None:
             if isinstance(iterable, _collections_abc.Mapping):
                 if self:
@@ -648,13 +673,14 @@ class Counter(dict):
                     for elem, count in iterable.items():
                         self[elem] = count + self_get(elem, 0)
                 else:
-                    super(Counter, self).update(iterable) # fast path when counter is empty
+                    # fast path when counter is empty
+                    super().update(iterable)
             else:
                 _count_elements(self, iterable)
         if kwds:
             self.update(kwds)
 
-    def subtract(*args, **kwds):
+    def subtract(self, iterable=None, /, **kwds):
         '''Like dict.update() but subtracts counts instead of replacing them.
         Counts can be reduced below zero.  Both the inputs and outputs are
         allowed to contain zero and negative counts.
@@ -670,13 +696,6 @@ class Counter(dict):
         -1
 
         '''
-        if not args:
-            raise TypeError("descriptor 'subtract' of 'Counter' object "
-                            "needs an argument")
-        self, *args = args
-        if len(args) > 1:
-            raise TypeError('expected at most 1 arguments, got %d' % len(args))
-        iterable = args[0] if args else None
         if iterable is not None:
             self_get = self.get
             if isinstance(iterable, _collections_abc.Mapping):
@@ -702,13 +721,14 @@ class Counter(dict):
 
     def __repr__(self):
         if not self:
-            return '%s()' % self.__class__.__name__
+            return f'{self.__class__.__name__}()'
         try:
-            items = ', '.join(map('%r: %r'.__mod__, self.most_common()))
+            # dict() preserves the ordering returned by most_common()
-            return '%s({%s})' % (self.__class__.__name__, items)
+            d = dict(self.most_common())
         except TypeError:
             # handle case where values are not orderable
-            return '{0}({1!r})'.format(self.__class__.__name__, dict(self))
+            d = dict(self)
+        return f'{self.__class__.__name__}({d!r})'
 
     # Multiset-style mathematical operations discussed in:
     #       Knuth TAOCP Volume II section 4.6.3 exercise 19
@@ -718,6 +738,13 @@ class Counter(dict):
     #
     # To strip negative and zero counts, add-in an empty counter:
     #       c += Counter()
+    #
+    # Rich comparison operators for multiset subset and superset tests
+    # are deliberately omitted due to semantic conflicts with the
+    # existing inherited dict equality method.  Subset and superset
+    # semantics ignore zero counts and require that p≤q ∧ p≥q → p=q;
+    # however, that would not be the case for p=Counter(a=1, b=0)
+    # and q=Counter(a=1) where the dictionaries are not equal.
 
     def __add__(self, other):
         '''Add counts from two counters.
@@ -922,7 +949,7 @@ class ChainMap(_collections_abc.MutableMapping):
     def __iter__(self):
         d = {}
         for mapping in reversed(self.maps):
-            d.update(mapping)                   # reuses stored hash values if possible
+            d.update(dict.fromkeys(mapping))    # reuses stored hash values if possible
         return iter(d)
 
     def __contains__(self, key):
@@ -933,8 +960,7 @@ class ChainMap(_collections_abc.MutableMapping):
 
     @_recursive_repr()
     def __repr__(self):
-        return '{0.__class__.__name__}({1})'.format(
+        return f'{self.__class__.__name__}({", ".join(map(repr, self.maps))})'
-            self, ', '.join(map(repr, self.maps)))
 
     @classmethod
     def fromkeys(cls, iterable, *args):
@@ -967,7 +993,7 @@ class ChainMap(_collections_abc.MutableMapping):
         try:
             del self.maps[0][key]
         except KeyError:
-            raise KeyError('Key not found in the first mapping: {!r}'.format(key))
+            raise KeyError(f'Key not found in the first mapping: {key!r}')
 
     def popitem(self):
         'Remove and return an item pair from maps[0]. Raise KeyError is maps[0] is empty.'
@@ -981,12 +1007,31 @@ class ChainMap(_collections_abc.MutableMapping):
         try:
             return self.maps[0].pop(key, *args)
         except KeyError:
-            raise KeyError('Key not found in the first mapping: {!r}'.format(key))
+            raise KeyError(f'Key not found in the first mapping: {key!r}')
 
     def clear(self):
         'Clear maps[0], leaving maps[1:] intact.'
         self.maps[0].clear()
 
+    def __ior__(self, other):
+        self.maps[0].update(other)
+        return self
+
+    def __or__(self, other):
+        if not isinstance(other, _collections_abc.Mapping):
+            return NotImplemented
+        m = self.copy()
+        m.maps[0].update(other)
+        return m
+
+    def __ror__(self, other):
+        if not isinstance(other, _collections_abc.Mapping):
+            return NotImplemented
+        m = dict(other)
+        for child in reversed(self.maps):
+            m.update(child)
+        return self.__class__(m)
+
 
 ################################################################################
 ### UserDict
@@ -995,36 +1040,29 @@ class ChainMap(_collections_abc.MutableMapping):
 class UserDict(_collections_abc.MutableMapping):
 
     # Start by filling-out the abstract methods
-    def __init__(*args, **kwargs):
+    def __init__(self, dict=None, /, **kwargs):
-        if not args:
-            raise TypeError("descriptor '__init__' of 'UserDict' object "
-                            "needs an argument")
-        self, *args = args
-        if len(args) > 1:
-            raise TypeError('expected at most 1 arguments, got %d' % len(args))
-        if args:
-            dict = args[0]
-        elif 'dict' in kwargs:
-            dict = kwargs.pop('dict')
-            import warnings
-            warnings.warn("Passing 'dict' as keyword argument is deprecated",
-                          DeprecationWarning, stacklevel=2)
-        else:
-            dict = None
         self.data = {}
         if dict is not None:
             self.update(dict)
-        if len(kwargs):
+        if kwargs:
             self.update(kwargs)
-    def __len__(self): return len(self.data)
+
+    def __len__(self):
+        return len(self.data)
+
     def __getitem__(self, key):
         if key in self.data:
             return self.data[key]
         if hasattr(self.__class__, "__missing__"):
             return self.__class__.__missing__(self, key)
         raise KeyError(key)
-    def __setitem__(self, key, item): self.data[key] = item
+
-    def __delitem__(self, key): del self.data[key]
+    def __setitem__(self, key, item):
+        self.data[key] = item
+
+    def __delitem__(self, key):
+        del self.data[key]
+
     def __iter__(self):
         return iter(self.data)
 
@@ -1033,7 +1071,37 @@ class UserDict(_collections_abc.MutableMapping):
         return key in self.data
 
     # Now, add the methods in dicts but not in MutableMapping
-    def __repr__(self): return repr(self.data)
+    def __repr__(self):
+        return repr(self.data)
+
+    def __or__(self, other):
+        if isinstance(other, UserDict):
+            return self.__class__(self.data | other.data)
+        if isinstance(other, dict):
+            return self.__class__(self.data | other)
+        return NotImplemented
+
+    def __ror__(self, other):
+        if isinstance(other, UserDict):
+            return self.__class__(other.data | self.data)
+        if isinstance(other, dict):
+            return self.__class__(other | self.data)
+        return NotImplemented
+
+    def __ior__(self, other):
+        if isinstance(other, UserDict):
+            self.data |= other.data
+        else:
+            self.data |= other
+        return self
+
+    def __copy__(self):
+        inst = self.__class__.__new__(self.__class__)
+        inst.__dict__.update(self.__dict__)
+        # Create a copy and avoid triggering descriptors
+        inst.__dict__["data"] = self.__dict__["data"].copy()
+        return inst
+
     def copy(self):
         if self.__class__ is UserDict:
             return UserDict(self.data.copy())
@@ -1046,6 +1114,7 @@ class UserDict(_collections_abc.MutableMapping):
             self.data = data
         c.update(self)
         return c
+
     @classmethod
     def fromkeys(cls, iterable, value=None):
         d = cls()
@@ -1054,13 +1123,13 @@ class UserDict(_collections_abc.MutableMapping):
         return d
 
 
-
 ################################################################################
 ### UserList
 ################################################################################
 
 class UserList(_collections_abc.MutableSequence):
     """A more or less complete user-defined wrapper around list objects."""
+
     def __init__(self, initlist=None):
         self.data = []
         if initlist is not None:
@@ -1071,31 +1140,60 @@ class UserList(_collections_abc.MutableSequence):
                 self.data[:] = initlist.data[:]
             else:
                 self.data = list(initlist)
-    def __repr__(self): return repr(self.data)
+
-    def __lt__(self, other): return self.data <  self.__cast(other)
+    def __repr__(self):
-    def __le__(self, other): return self.data <= self.__cast(other)
+        return repr(self.data)
-    def __eq__(self, other): return self.data == self.__cast(other)
+
-    def __gt__(self, other): return self.data >  self.__cast(other)
+    def __lt__(self, other):
-    def __ge__(self, other): return self.data >= self.__cast(other)
+        return self.data < self.__cast(other)
+
+    def __le__(self, other):
+        return self.data <= self.__cast(other)
+
+    def __eq__(self, other):
+        return self.data == self.__cast(other)
+
+    def __gt__(self, other):
+        return self.data > self.__cast(other)
+
+    def __ge__(self, other):
+        return self.data >= self.__cast(other)
+
     def __cast(self, other):
         return other.data if isinstance(other, UserList) else other
-    def __contains__(self, item): return item in self.data
+
-    def __len__(self): return len(self.data)
+    def __contains__(self, item):
-    def __getitem__(self, i): return self.data[i]
+        return item in self.data
-    def __setitem__(self, i, item): self.data[i] = item
+
-    def __delitem__(self, i): del self.data[i]
+    def __len__(self):
+        return len(self.data)
+
+    def __getitem__(self, i):
+        if isinstance(i, slice):
+            return self.__class__(self.data[i])
+        else:
+            return self.data[i]
+
+    def __setitem__(self, i, item):
+        self.data[i] = item
+
+    def __delitem__(self, i):
+        del self.data[i]
+
     def __add__(self, other):
         if isinstance(other, UserList):
             return self.__class__(self.data + other.data)
         elif isinstance(other, type(self.data)):
             return self.__class__(self.data + other)
         return self.__class__(self.data + list(other))
+
     def __radd__(self, other):
         if isinstance(other, UserList):
             return self.__class__(other.data + self.data)
         elif isinstance(other, type(self.data)):
             return self.__class__(other + self.data)
         return self.__class__(list(other) + self.data)
+
     def __iadd__(self, other):
         if isinstance(other, UserList):
             self.data += other.data
@@ -1104,22 +1202,53 @@ class UserList(_collections_abc.MutableSequence):
         else:
             self.data += list(other)
         return self
+
     def __mul__(self, n):
-        return self.__class__(self.data*n)
+        return self.__class__(self.data * n)
+
     __rmul__ = __mul__
+
     def __imul__(self, n):
         self.data *= n
         return self
-    def append(self, item): self.data.append(item)
+
-    def insert(self, i, item): self.data.insert(i, item)
+    def __copy__(self):
-    def pop(self, i=-1): return self.data.pop(i)
+        inst = self.__class__.__new__(self.__class__)
-    def remove(self, item): self.data.remove(item)
+        inst.__dict__.update(self.__dict__)
-    def clear(self): self.data.clear()
+        # Create a copy and avoid triggering descriptors
-    def copy(self): return self.__class__(self)
+        inst.__dict__["data"] = self.__dict__["data"][:]
-    def count(self, item): return self.data.count(item)
+        return inst
-    def index(self, item, *args): return self.data.index(item, *args)
+
-    def reverse(self): self.data.reverse()
+    def append(self, item):
-    def sort(self, *args, **kwds): self.data.sort(*args, **kwds)
+        self.data.append(item)
+
+    def insert(self, i, item):
+        self.data.insert(i, item)
+
+    def pop(self, i=-1):
+        return self.data.pop(i)
+
+    def remove(self, item):
+        self.data.remove(item)
+
+    def clear(self):
+        self.data.clear()
+
+    def copy(self):
+        return self.__class__(self)
+
+    def count(self, item):
+        return self.data.count(item)
+
+    def index(self, item, *args):
+        return self.data.index(item, *args)
+
+    def reverse(self):
+        self.data.reverse()
+
+    def sort(self, /, *args, **kwds):
+        self.data.sort(*args, **kwds)
+
     def extend(self, other):
         if isinstance(other, UserList):
             self.data.extend(other.data)
@@ -1127,12 +1256,12 @@ class UserList(_collections_abc.MutableSequence):
             self.data.extend(other)
 
 
-
 ################################################################################
 ### UserString
 ################################################################################
 
 class UserString(_collections_abc.Sequence):
+
     def __init__(self, seq):
         if isinstance(seq, str):
             self.data = seq
@@ -1140,12 +1269,25 @@ class UserString(_collections_abc.Sequence):
             self.data = seq.data[:]
         else:
             self.data = str(seq)
-    def __str__(self): return str(self.data)
+
-    def __repr__(self): return repr(self.data)
+    def __str__(self):
-    def __int__(self): return int(self.data)
+        return str(self.data)
-    def __float__(self): return float(self.data)
+
-    def __complex__(self): return complex(self.data)
+    def __repr__(self):
-    def __hash__(self): return hash(self.data)
+        return repr(self.data)
+
+    def __int__(self):
+        return int(self.data)
+
+    def __float__(self):
+        return float(self.data)
+
+    def __complex__(self):
+        return complex(self.data)
+
+    def __hash__(self):
+        return hash(self.data)
+
     def __getnewargs__(self):
         return (self.data[:],)
 
@@ -1153,18 +1295,22 @@ class UserString(_collections_abc.Sequence):
         if isinstance(string, UserString):
             return self.data == string.data
         return self.data == string
+
     def __lt__(self, string):
         if isinstance(string, UserString):
             return self.data < string.data
         return self.data < string
+
     def __le__(self, string):
         if isinstance(string, UserString):
             return self.data <= string.data
         return self.data <= string
+
     def __gt__(self, string):
         if isinstance(string, UserString):
             return self.data > string.data
         return self.data > string
+
     def __ge__(self, string):
         if isinstance(string, UserString):
             return self.data >= string.data
@@ -1175,105 +1321,188 @@ class UserString(_collections_abc.Sequence):
             char = char.data
         return char in self.data
 
-    def __len__(self): return len(self.data)
+    def __len__(self):
-    def __getitem__(self, index): return self.__class__(self.data[index])
+        return len(self.data)
+
+    def __getitem__(self, index):
+        return self.__class__(self.data[index])
+
     def __add__(self, other):
         if isinstance(other, UserString):
             return self.__class__(self.data + other.data)
         elif isinstance(other, str):
             return self.__class__(self.data + other)
         return self.__class__(self.data + str(other))
+
     def __radd__(self, other):
         if isinstance(other, str):
             return self.__class__(other + self.data)
         return self.__class__(str(other) + self.data)
+
     def __mul__(self, n):
-        return self.__class__(self.data*n)
+        return self.__class__(self.data * n)
+
     __rmul__ = __mul__
+
     def __mod__(self, args):
         return self.__class__(self.data % args)
-    def __rmod__(self, format):
+
-        return self.__class__(format % args)
+    def __rmod__(self, template):
+        return self.__class__(str(template) % self)
 
     # the following methods are defined in alphabetical order:
-    def capitalize(self): return self.__class__(self.data.capitalize())
+    def capitalize(self):
+        return self.__class__(self.data.capitalize())
+
     def casefold(self):
         return self.__class__(self.data.casefold())
+
     def center(self, width, *args):
         return self.__class__(self.data.center(width, *args))
+
     def count(self, sub, start=0, end=_sys.maxsize):
         if isinstance(sub, UserString):
             sub = sub.data
         return self.data.count(sub, start, end)
-    def encode(self, encoding=None, errors=None): # XXX improve this?
+
-        if encoding:
+    def removeprefix(self, prefix, /):
-            if errors:
+        if isinstance(prefix, UserString):
-                return self.__class__(self.data.encode(encoding, errors))
+            prefix = prefix.data
-            return self.__class__(self.data.encode(encoding))
+        return self.__class__(self.data.removeprefix(prefix))
-        return self.__class__(self.data.encode())
+
+    def removesuffix(self, suffix, /):
+        if isinstance(suffix, UserString):
+            suffix = suffix.data
+        return self.__class__(self.data.removesuffix(suffix))
+
+    def encode(self, encoding='utf-8', errors='strict'):
+        encoding = 'utf-8' if encoding is None else encoding
+        errors = 'strict' if errors is None else errors
+        return self.data.encode(encoding, errors)
+
     def endswith(self, suffix, start=0, end=_sys.maxsize):
         return self.data.endswith(suffix, start, end)
+
     def expandtabs(self, tabsize=8):
         return self.__class__(self.data.expandtabs(tabsize))
+
     def find(self, sub, start=0, end=_sys.maxsize):
         if isinstance(sub, UserString):
             sub = sub.data
         return self.data.find(sub, start, end)
-    def format(self, *args, **kwds):
+
+    def format(self, /, *args, **kwds):
         return self.data.format(*args, **kwds)
+
     def format_map(self, mapping):
         return self.data.format_map(mapping)
+
     def index(self, sub, start=0, end=_sys.maxsize):
         return self.data.index(sub, start, end)
-    def isalpha(self): return self.data.isalpha()
+
-    def isalnum(self): return self.data.isalnum()
+    def isalpha(self):
-    def isascii(self): return self.data.isascii()
+        return self.data.isalpha()
-    def isdecimal(self): return self.data.isdecimal()
+
-    def isdigit(self): return self.data.isdigit()
+    def isalnum(self):
-    def isidentifier(self): return self.data.isidentifier()
+        return self.data.isalnum()
-    def islower(self): return self.data.islower()
+
-    def isnumeric(self): return self.data.isnumeric()
+    def isascii(self):
-    def isprintable(self): return self.data.isprintable()
+        return self.data.isascii()
-    def isspace(self): return self.data.isspace()
+
-    def istitle(self): return self.data.istitle()
+    def isdecimal(self):
-    def isupper(self): return self.data.isupper()
+        return self.data.isdecimal()
-    def join(self, seq): return self.data.join(seq)
+
+    def isdigit(self):
+        return self.data.isdigit()
+
+    def isidentifier(self):
+        return self.data.isidentifier()
+
+    def islower(self):
+        return self.data.islower()
+
+    def isnumeric(self):
+        return self.data.isnumeric()
+
+    def isprintable(self):
+        return self.data.isprintable()
+
+    def isspace(self):
+        return self.data.isspace()
+
+    def istitle(self):
+        return self.data.istitle()
+
+    def isupper(self):
+        return self.data.isupper()
+
+    def join(self, seq):
+        return self.data.join(seq)
+
     def ljust(self, width, *args):
         return self.__class__(self.data.ljust(width, *args))
-    def lower(self): return self.__class__(self.data.lower())
+
-    def lstrip(self, chars=None): return self.__class__(self.data.lstrip(chars))
+    def lower(self):
+        return self.__class__(self.data.lower())
+
+    def lstrip(self, chars=None):
+        return self.__class__(self.data.lstrip(chars))
+
     maketrans = str.maketrans
+
     def partition(self, sep):
         return self.data.partition(sep)
+
     def replace(self, old, new, maxsplit=-1):
         if isinstance(old, UserString):
             old = old.data
         if isinstance(new, UserString):
             new = new.data
         return self.__class__(self.data.replace(old, new, maxsplit))
+
     def rfind(self, sub, start=0, end=_sys.maxsize):
         if isinstance(sub, UserString):
             sub = sub.data
         return self.data.rfind(sub, start, end)
+
     def rindex(self, sub, start=0, end=_sys.maxsize):
         return self.data.rindex(sub, start, end)
+
     def rjust(self, width, *args):
         return self.__class__(self.data.rjust(width, *args))
+
     def rpartition(self, sep):
         return self.data.rpartition(sep)
+
     def rstrip(self, chars=None):
         return self.__class__(self.data.rstrip(chars))
+
     def split(self, sep=None, maxsplit=-1):
         return self.data.split(sep, maxsplit)
+
     def rsplit(self, sep=None, maxsplit=-1):
         return self.data.rsplit(sep, maxsplit)
-    def splitlines(self, keepends=False): return self.data.splitlines(keepends)
+
+    def splitlines(self, keepends=False):
+        return self.data.splitlines(keepends)
+
     def startswith(self, prefix, start=0, end=_sys.maxsize):
         return self.data.startswith(prefix, start, end)
-    def strip(self, chars=None): return self.__class__(self.data.strip(chars))
+
-    def swapcase(self): return self.__class__(self.data.swapcase())
+    def strip(self, chars=None):
-    def title(self): return self.__class__(self.data.title())
+        return self.__class__(self.data.strip(chars))
+
+    def swapcase(self):
+        return self.__class__(self.data.swapcase())
+
+    def title(self):
+        return self.__class__(self.data.title())
+
     def translate(self, *args):
         return self.__class__(self.data.translate(*args))
-    def upper(self): return self.__class__(self.data.upper())
+
-    def zfill(self, width): return self.__class__(self.data.zfill(width))
+    def upper(self):
+        return self.__class__(self.data.upper())
+
+    def zfill(self, width):
+        return self.__class__(self.data.zfill(width))

extlib/Python/Lib/collections/abc.py

@@ -1,2 +1,3 @@
 from _collections_abc import *
 from _collections_abc import __all__
+from _collections_abc import _CallableGenericAlias

extlib/Python/Lib/compileall.py

@@ -15,16 +15,14 @@ import sys
 import importlib.util
 import py_compile
 import struct
+import filecmp
 
-try:
-    from concurrent.futures import ProcessPoolExecutor
-except ImportError:
-    ProcessPoolExecutor = None
 from functools import partial
+from pathlib import Path
 
 __all__ = ["compile_dir","compile_file","compile_path"]
 
-def _walk_dir(dir, ddir=None, maxlevels=10, quiet=0):
+def _walk_dir(dir, maxlevels, quiet=0):
     if quiet < 2 and isinstance(dir, os.PathLike):
         dir = os.fspath(dir)
     if not quiet:
@@ -40,43 +38,64 @@ def _walk_dir(dir, ddir=None, maxlevels=10, quiet=0):
         if name == '__pycache__':
             continue
         fullname = os.path.join(dir, name)
-        if ddir is not None:
-            dfile = os.path.join(ddir, name)
-        else:
-            dfile = None
         if not os.path.isdir(fullname):
             yield fullname
         elif (maxlevels > 0 and name != os.curdir and name != os.pardir and
               os.path.isdir(fullname) and not os.path.islink(fullname)):
-            yield from _walk_dir(fullname, ddir=dfile,
+            yield from _walk_dir(fullname, maxlevels=maxlevels - 1,
-                                 maxlevels=maxlevels - 1, quiet=quiet)
+                                 quiet=quiet)
 
-def compile_dir(dir, maxlevels=10, ddir=None, force=False, rx=None,
+def compile_dir(dir, maxlevels=None, ddir=None, force=False,
-                quiet=0, legacy=False, optimize=-1, workers=1,
+                rx=None, quiet=0, legacy=False, optimize=-1, workers=1,
-                invalidation_mode=py_compile.PycInvalidationMode.TIMESTAMP):
+                invalidation_mode=None, *, stripdir=None,
+                prependdir=None, limit_sl_dest=None, hardlink_dupes=False):
     """Byte-compile all modules in the given directory tree.
 
     Arguments (only dir is required):
 
     dir:       the directory to byte-compile
-    maxlevels: maximum recursion level (default 10)
+    maxlevels: maximum recursion level (default `sys.getrecursionlimit()`)
     ddir:      the directory that will be prepended to the path to the
                file as it is compiled into each byte-code file.
     force:     if True, force compilation, even if timestamps are up-to-date
     quiet:     full output with False or 0, errors only with 1,
                no output with 2
     legacy:    if True, produce legacy pyc paths instead of PEP 3147 paths
-    optimize:  optimization level or -1 for level of the interpreter
+    optimize:  int or list of optimization levels or -1 for level of
+               the interpreter. Multiple levels leads to multiple compiled
+               files each with one optimization level.
     workers:   maximum number of parallel workers
     invalidation_mode: how the up-to-dateness of the pyc will be checked
+    stripdir:  part of path to left-strip from source file path
+    prependdir: path to prepend to beginning of original file path, applied
+               after stripdir
+    limit_sl_dest: ignore symlinks if they are pointing outside of
+                   the defined path
+    hardlink_dupes: hardlink duplicated pyc files
     """
-    if workers is not None and workers < 0:
+    ProcessPoolExecutor = None
+    if ddir is not None and (stripdir is not None or prependdir is not None):
+        raise ValueError(("Destination dir (ddir) cannot be used "
+                          "in combination with stripdir or prependdir"))
+    if ddir is not None:
+        stripdir = dir
+        prependdir = ddir
+        ddir = None
+    if workers < 0:
         raise ValueError('workers must be greater or equal to 0')
-
+    if workers != 1:
-    files = _walk_dir(dir, quiet=quiet, maxlevels=maxlevels,
+        try:
-                      ddir=ddir)
+            # Only import when needed, as low resource platforms may
+            # fail to import it
+            from concurrent.futures import ProcessPoolExecutor
+        except ImportError:
+            workers = 1
+    if maxlevels is None:
+        maxlevels = sys.getrecursionlimit()
+    files = _walk_dir(dir, quiet=quiet, maxlevels=maxlevels)
     success = True
-    if workers is not None and workers != 1 and ProcessPoolExecutor is not None:
+    if workers != 1 and ProcessPoolExecutor is not None:
+        # If workers == 0, let ProcessPoolExecutor choose
         workers = workers or None
         with ProcessPoolExecutor(max_workers=workers) as executor:
             results = executor.map(partial(compile_file,
@@ -84,19 +103,27 @@ def compile_dir(dir, maxlevels=10, ddir=None, force=False, rx=None,
                                            rx=rx, quiet=quiet,
                                            legacy=legacy,
                                            optimize=optimize,
-                                           invalidation_mode=invalidation_mode),
+                                           invalidation_mode=invalidation_mode,
+                                           stripdir=stripdir,
+                                           prependdir=prependdir,
+                                           limit_sl_dest=limit_sl_dest,
+                                           hardlink_dupes=hardlink_dupes),
                                    files)
             success = min(results, default=True)
     else:
         for file in files:
             if not compile_file(file, ddir, force, rx, quiet,
-                                legacy, optimize, invalidation_mode):
+                                legacy, optimize, invalidation_mode,
+                                stripdir=stripdir, prependdir=prependdir,
+                                limit_sl_dest=limit_sl_dest,
+                                hardlink_dupes=hardlink_dupes):
                 success = False
     return success
 
 def compile_file(fullname, ddir=None, force=False, rx=None, quiet=0,
                  legacy=False, optimize=-1,
-                 invalidation_mode=py_compile.PycInvalidationMode.TIMESTAMP):
+                 invalidation_mode=None, *, stripdir=None, prependdir=None,
+                 limit_sl_dest=None, hardlink_dupes=False):
     """Byte-compile one file.
 
     Arguments (only fullname is required):
@@ -108,51 +135,114 @@ def compile_file(fullname, ddir=None, force=False, rx=None, quiet=0,
     quiet:     full output with False or 0, errors only with 1,
                no output with 2
     legacy:    if True, produce legacy pyc paths instead of PEP 3147 paths
-    optimize:  optimization level or -1 for level of the interpreter
+    optimize:  int or list of optimization levels or -1 for level of
+               the interpreter. Multiple levels leads to multiple compiled
+               files each with one optimization level.
     invalidation_mode: how the up-to-dateness of the pyc will be checked
+    stripdir:  part of path to left-strip from source file path
+    prependdir: path to prepend to beginning of original file path, applied
+               after stripdir
+    limit_sl_dest: ignore symlinks if they are pointing outside of
+                   the defined path.
+    hardlink_dupes: hardlink duplicated pyc files
     """
+
+    if ddir is not None and (stripdir is not None or prependdir is not None):
+        raise ValueError(("Destination dir (ddir) cannot be used "
+                          "in combination with stripdir or prependdir"))
+
     success = True
     if quiet < 2 and isinstance(fullname, os.PathLike):
         fullname = os.fspath(fullname)
     name = os.path.basename(fullname)
+
+    dfile = None
+
     if ddir is not None:
         dfile = os.path.join(ddir, name)
-    else:
+
-        dfile = None
+    if stripdir is not None:
+        fullname_parts = fullname.split(os.path.sep)
+        stripdir_parts = stripdir.split(os.path.sep)
+        ddir_parts = list(fullname_parts)
+
+        for spart, opart in zip(stripdir_parts, fullname_parts):
+            if spart == opart:
+                ddir_parts.remove(spart)
+
+        dfile = os.path.join(*ddir_parts)
+
+    if prependdir is not None:
+        if dfile is None:
+            dfile = os.path.join(prependdir, fullname)
+        else:
+            dfile = os.path.join(prependdir, dfile)
+
+    if isinstance(optimize, int):
+        optimize = [optimize]
+
+    # Use set() to remove duplicates.
+    # Use sorted() to create pyc files in a deterministic order.
+    optimize = sorted(set(optimize))
+
+    if hardlink_dupes and len(optimize) < 2:
+        raise ValueError("Hardlinking of duplicated bytecode makes sense "
+                          "only for more than one optimization level")
+
     if rx is not None:
         mo = rx.search(fullname)
         if mo:
             return success
+
+    if limit_sl_dest is not None and os.path.islink(fullname):
+        if Path(limit_sl_dest).resolve() not in Path(fullname).resolve().parents:
+            return success
+
+    opt_cfiles = {}
+
     if os.path.isfile(fullname):
-        if legacy:
+        for opt_level in optimize:
-            cfile = fullname + 'c'
+            if legacy:
-        else:
+                opt_cfiles[opt_level] = fullname + 'c'
-            if optimize >= 0:
-                opt = optimize if optimize >= 1 else ''
-                cfile = importlib.util.cache_from_source(
-                                fullname, optimization=opt)
             else:
-                cfile = importlib.util.cache_from_source(fullname)
+                if opt_level >= 0:
-            cache_dir = os.path.dirname(cfile)
+                    opt = opt_level if opt_level >= 1 else ''
+                    cfile = (importlib.util.cache_from_source(
+                             fullname, optimization=opt))
+                    opt_cfiles[opt_level] = cfile
+                else:
+                    cfile = importlib.util.cache_from_source(fullname)
+                    opt_cfiles[opt_level] = cfile
+
         head, tail = name[:-3], name[-3:]
         if tail == '.py':
             if not force:
                 try:
                     mtime = int(os.stat(fullname).st_mtime)
-                    expect = struct.pack('<4sll', importlib.util.MAGIC_NUMBER,
+                    expect = struct.pack('<4sLL', importlib.util.MAGIC_NUMBER,
-                                         0, mtime)
+                                         0, mtime & 0xFFFF_FFFF)
-                    with open(cfile, 'rb') as chandle:
+                    for cfile in opt_cfiles.values():
-                        actual = chandle.read(12)
+                        with open(cfile, 'rb') as chandle:
-                    if expect == actual:
+                            actual = chandle.read(12)
+                        if expect != actual:
+                            break
+                    else:
                         return success
                 except OSError:
                     pass
             if not quiet:
                 print('Compiling {!r}...'.format(fullname))
             try:
-                ok = py_compile.compile(fullname, cfile, dfile, True,
+                for index, opt_level in enumerate(optimize):
-                                        optimize=optimize,
+                    cfile = opt_cfiles[opt_level]
-                                        invalidation_mode=invalidation_mode)
+                    ok = py_compile.compile(fullname, cfile, dfile, True,
+                                            optimize=opt_level,
+                                            invalidation_mode=invalidation_mode)
+                    if index > 0 and hardlink_dupes:
+                        previous_cfile = opt_cfiles[optimize[index - 1]]
+                        if filecmp.cmp(cfile, previous_cfile, shallow=False):
+                            os.unlink(cfile)
+                            os.link(previous_cfile, cfile)
             except py_compile.PyCompileError as err:
                 success = False
                 if quiet >= 2:
@@ -162,9 +252,8 @@ def compile_file(fullname, ddir=None, force=False, rx=None, quiet=0,
                 else:
                     print('*** ', end='')
                 # escape non-printable characters in msg
-                msg = err.msg.encode(sys.stdout.encoding,
+                encoding = sys.stdout.encoding or sys.getdefaultencoding()
-                                     errors='backslashreplace')
+                msg = err.msg.encode(encoding, errors='backslashreplace').decode(encoding)
-                msg = msg.decode(sys.stdout.encoding)
                 print(msg)
             except (SyntaxError, UnicodeError, OSError) as e:
                 success = False
@@ -182,7 +271,7 @@ def compile_file(fullname, ddir=None, force=False, rx=None, quiet=0,
 
 def compile_path(skip_curdir=1, maxlevels=0, force=False, quiet=0,
                  legacy=False, optimize=-1,
-                 invalidation_mode=py_compile.PycInvalidationMode.TIMESTAMP):
+                 invalidation_mode=None):
     """Byte-compile all module on sys.path.
 
     Arguments (all optional):
@@ -221,7 +310,7 @@ def main():
     parser = argparse.ArgumentParser(
         description='Utilities to support installing Python libraries.')
     parser.add_argument('-l', action='store_const', const=0,
-                        default=10, dest='maxlevels',
+                        default=None, dest='maxlevels',
                         help="don't recurse into subdirectories")
     parser.add_argument('-r', type=int, dest='recursion',
                         help=('control the maximum recursion level. '
@@ -239,6 +328,20 @@ def main():
                               'compile-time tracebacks and in runtime '
                               'tracebacks in cases where the source file is '
                               'unavailable'))
+    parser.add_argument('-s', metavar='STRIPDIR',  dest='stripdir',
+                        default=None,
+                        help=('part of path to left-strip from path '
+                              'to source file - for example buildroot. '
+                              '`-d` and `-s` options cannot be '
+                              'specified together.'))
+    parser.add_argument('-p', metavar='PREPENDDIR',  dest='prependdir',
+                        default=None,
+                        help=('path to add as prefix to path '
+                              'to source file - for example / to make '
+                              'it absolute when some part is removed '
+                              'by `-s` option. '
+                              '`-d` and `-p` options cannot be '
+                              'specified together.'))
     parser.add_argument('-x', metavar='REGEXP', dest='rx', default=None,
                         help=('skip files matching the regular expression; '
                               'the regexp is searched for in the full path '
@@ -255,9 +358,21 @@ def main():
                         type=int, help='Run compileall concurrently')
     invalidation_modes = [mode.name.lower().replace('_', '-')
                           for mode in py_compile.PycInvalidationMode]
-    parser.add_argument('--invalidation-mode', default='timestamp',
+    parser.add_argument('--invalidation-mode',
                         choices=sorted(invalidation_modes),
-                        help='How the pycs will be invalidated at runtime')
+                        help=('set .pyc invalidation mode; defaults to '
+                              '"checked-hash" if the SOURCE_DATE_EPOCH '
+                              'environment variable is set, and '
+                              '"timestamp" otherwise.'))
+    parser.add_argument('-o', action='append', type=int, dest='opt_levels',
+                        help=('Optimization levels to run compilation with. '
+                              'Default is -1 which uses the optimization level '
+                              'of the Python interpreter itself (see -O).'))
+    parser.add_argument('-e', metavar='DIR', dest='limit_sl_dest',
+                        help='Ignore symlinks pointing outsite of the DIR')
+    parser.add_argument('--hardlink-dupes', action='store_true',
+                        dest='hardlink_dupes',
+                        help='Hardlink duplicated pyc files')
 
     args = parser.parse_args()
     compile_dests = args.compile_dest
@@ -266,12 +381,26 @@ def main():
         import re
         args.rx = re.compile(args.rx)
 
+    if args.limit_sl_dest == "":
+        args.limit_sl_dest = None
 
     if args.recursion is not None:
         maxlevels = args.recursion
     else:
         maxlevels = args.maxlevels
 
+    if args.opt_levels is None:
+        args.opt_levels = [-1]
+
+    if len(args.opt_levels) == 1 and args.hardlink_dupes:
+        parser.error(("Hardlinking of duplicated bytecode makes sense "
+                      "only for more than one optimization level."))
+
+    if args.ddir is not None and (
+        args.stripdir is not None or args.prependdir is not None
+    ):
+        parser.error("-d cannot be used in combination with -s or -p")
+
     # if flist is provided then load it
     if args.flist:
         try:
@@ -283,11 +412,11 @@ def main():
                 print("Error reading file list {}".format(args.flist))
             return False
 
-    if args.workers is not None:
+    if args.invalidation_mode:
-        args.workers = args.workers or None
+        ivl_mode = args.invalidation_mode.replace('-', '_').upper()
-
+        invalidation_mode = py_compile.PycInvalidationMode[ivl_mode]
-    ivl_mode = args.invalidation_mode.replace('-', '_').upper()
+    else:
-    invalidation_mode = py_compile.PycInvalidationMode[ivl_mode]
+        invalidation_mode = None
 
     success = True
     try:
@@ -296,13 +425,23 @@ def main():
                 if os.path.isfile(dest):
                     if not compile_file(dest, args.ddir, args.force, args.rx,
                                         args.quiet, args.legacy,
-                                        invalidation_mode=invalidation_mode):
+                                        invalidation_mode=invalidation_mode,
+                                        stripdir=args.stripdir,
+                                        prependdir=args.prependdir,
+                                        optimize=args.opt_levels,
+                                        limit_sl_dest=args.limit_sl_dest,
+                                        hardlink_dupes=args.hardlink_dupes):
                         success = False
                 else:
                     if not compile_dir(dest, maxlevels, args.ddir,
                                        args.force, args.rx, args.quiet,
                                        args.legacy, workers=args.workers,
-                                       invalidation_mode=invalidation_mode):
+                                       invalidation_mode=invalidation_mode,
+                                       stripdir=args.stripdir,
+                                       prependdir=args.prependdir,
+                                       optimize=args.opt_levels,
+                                       limit_sl_dest=args.limit_sl_dest,
+                                       hardlink_dupes=args.hardlink_dupes):
                         success = False
             return success
         else:

extlib/Python/Lib/concurrent/futures/__init__.py

@@ -10,6 +10,7 @@ from concurrent.futures._base import (FIRST_COMPLETED,
                                       ALL_COMPLETED,
                                       CancelledError,
                                       TimeoutError,
+                                      InvalidStateError,
                                       BrokenExecutor,
                                       Future,
                                       Executor,

extlib/Python/Lib/concurrent/futures/_base.py

@@ -7,6 +7,7 @@ import collections
 import logging
 import threading
 import time
+import types
 
 FIRST_COMPLETED = 'FIRST_COMPLETED'
 FIRST_EXCEPTION = 'FIRST_EXCEPTION'
@@ -53,6 +54,10 @@ class TimeoutError(Error):
     """The operation exceeded the given deadline."""
     pass
 
+class InvalidStateError(Error):
+    """The operation is not allowed in this state."""
+    pass
+
 class _Waiter(object):
     """Provides the event that wait() and as_completed() block on."""
     def __init__(self):
@@ -212,7 +217,7 @@ def as_completed(fs, timeout=None):
             before the given timeout.
     """
     if timeout is not None:
-        end_time = timeout + time.time()
+        end_time = timeout + time.monotonic()
 
     fs = set(fs)
     total_futures = len(fs)
@@ -231,7 +236,7 @@ def as_completed(fs, timeout=None):
             if timeout is None:
                 wait_timeout = None
             else:
-                wait_timeout = end_time - time.time()
+                wait_timeout = end_time - time.monotonic()
                 if wait_timeout < 0:
                     raise TimeoutError(
                             '%d (of %d) futures unfinished' % (
@@ -279,13 +284,14 @@ def wait(fs, timeout=None, return_when=ALL_COMPLETED):
         A named 2-tuple of sets. The first set, named 'done', contains the
         futures that completed (is finished or cancelled) before the wait
         completed. The second set, named 'not_done', contains uncompleted
-        futures.
+        futures. Duplicate futures given to *fs* are removed and will be 
+        returned only once.
     """
+    fs = set(fs)
     with _AcquireFutures(fs):
-        done = set(f for f in fs
+        done = {f for f in fs
-                   if f._state in [CANCELLED_AND_NOTIFIED, FINISHED])
+                   if f._state in [CANCELLED_AND_NOTIFIED, FINISHED]}
-        not_done = set(fs) - done
+        not_done = fs - done
-
         if (return_when == FIRST_COMPLETED) and done:
             return DoneAndNotDoneFutures(done, not_done)
         elif (return_when == FIRST_EXCEPTION) and done:
@@ -304,7 +310,7 @@ def wait(fs, timeout=None, return_when=ALL_COMPLETED):
             f._waiters.remove(waiter)
 
     done.update(waiter.finished_futures)
-    return DoneAndNotDoneFutures(done, set(fs) - done)
+    return DoneAndNotDoneFutures(done, fs - done)
 
 class Future(object):
     """Represents the result of an asynchronous computation."""
@@ -375,13 +381,17 @@ class Future(object):
             return self._state == RUNNING
 
     def done(self):
-        """Return True of the future was cancelled or finished executing."""
+        """Return True if the future was cancelled or finished executing."""
         with self._condition:
             return self._state in [CANCELLED, CANCELLED_AND_NOTIFIED, FINISHED]
 
     def __get_result(self):
         if self._exception:
-            raise self._exception
+            try:
+                raise self._exception
+            finally:
+                # Break a reference cycle with the exception in self._exception
+                self = None
         else:
             return self._result
 
@@ -400,7 +410,10 @@ class Future(object):
             if self._state not in [CANCELLED, CANCELLED_AND_NOTIFIED, FINISHED]:
                 self._done_callbacks.append(fn)
                 return
-        fn(self)
+        try:
+            fn(self)
+        except Exception:
+            LOGGER.exception('exception calling callback for %r', self)
 
     def result(self, timeout=None):
         """Return the result of the call that the future represents.
@@ -418,20 +431,24 @@ class Future(object):
                 timeout.
             Exception: If the call raised then that exception will be raised.
         """
-        with self._condition:
+        try:
-            if self._state in [CANCELLED, CANCELLED_AND_NOTIFIED]:
+            with self._condition:
-                raise CancelledError()
+                if self._state in [CANCELLED, CANCELLED_AND_NOTIFIED]:
-            elif self._state == FINISHED:
+                    raise CancelledError()
-                return self.__get_result()
+                elif self._state == FINISHED:
+                    return self.__get_result()
 
-            self._condition.wait(timeout)
+                self._condition.wait(timeout)
 
-            if self._state in [CANCELLED, CANCELLED_AND_NOTIFIED]:
+                if self._state in [CANCELLED, CANCELLED_AND_NOTIFIED]:
-                raise CancelledError()
+                    raise CancelledError()
-            elif self._state == FINISHED:
+                elif self._state == FINISHED:
-                return self.__get_result()
+                    return self.__get_result()
-            else:
+                else:
-                raise TimeoutError()
+                    raise TimeoutError()
+        finally:
+            # Break a reference cycle with the exception in self._exception
+            self = None
 
     def exception(self, timeout=None):
         """Return the exception raised by the call that the future represents.
@@ -513,6 +530,8 @@ class Future(object):
         Should only be used by Executor implementations and unit tests.
         """
         with self._condition:
+            if self._state in {CANCELLED, CANCELLED_AND_NOTIFIED, FINISHED}:
+                raise InvalidStateError('{}: {!r}'.format(self._state, self))
             self._result = result
             self._state = FINISHED
             for waiter in self._waiters:
@@ -526,6 +545,8 @@ class Future(object):
         Should only be used by Executor implementations and unit tests.
         """
         with self._condition:
+            if self._state in {CANCELLED, CANCELLED_AND_NOTIFIED, FINISHED}:
+                raise InvalidStateError('{}: {!r}'.format(self._state, self))
             self._exception = exception
             self._state = FINISHED
             for waiter in self._waiters:
@@ -533,10 +554,12 @@ class Future(object):
             self._condition.notify_all()
         self._invoke_callbacks()
 
+    __class_getitem__ = classmethod(types.GenericAlias)
+
 class Executor(object):
     """This is an abstract base class for concrete asynchronous executors."""
 
-    def submit(self, fn, *args, **kwargs):
+    def submit(self, fn, /, *args, **kwargs):
         """Submits a callable to be executed with the given arguments.
 
         Schedules the callable to be executed as fn(*args, **kwargs) and returns
@@ -570,7 +593,7 @@ class Executor(object):
             Exception: If fn(*args) raises for any values.
         """
         if timeout is not None:
-            end_time = timeout + time.time()
+            end_time = timeout + time.monotonic()
 
         fs = [self.submit(fn, *args) for args in zip(*iterables)]
 
@@ -585,13 +608,13 @@ class Executor(object):
                     if timeout is None:
                         yield fs.pop().result()
                     else:
-                        yield fs.pop().result(end_time - time.time())
+                        yield fs.pop().result(end_time - time.monotonic())
             finally:
                 for future in fs:
                     future.cancel()
         return result_iterator()
 
-    def shutdown(self, wait=True):
+    def shutdown(self, wait=True, *, cancel_futures=False):
         """Clean-up the resources associated with the Executor.
 
         It is safe to call this method several times. Otherwise, no other
@@ -601,6 +624,9 @@ class Executor(object):
             wait: If True then shutdown will not return until all running
                 futures have finished executing and the resources used by the
                 executor have been reclaimed.
+            cancel_futures: If True then shutdown will cancel all pending
+                futures. Futures that are completed or running will not be
+                cancelled.
         """
         pass
 

extlib/Python/Lib/concurrent/futures/process.py

@@ -3,7 +3,7 @@
 
 """Implements ProcessPoolExecutor.
 
-The follow diagram and text describe the data-flow through the system:
+The following diagram and text describe the data-flow through the system:
 
 |======================= In-process =====================|== Out-of-process ==|
 
@@ -45,33 +45,19 @@ Process #1..n:
 
 __author__ = 'Brian Quinlan (brian@sweetapp.com)'
 
-import atexit
 import os
 from concurrent.futures import _base
 import queue
-from queue import Full
 import multiprocessing as mp
-from multiprocessing.connection import wait
+import multiprocessing.connection
 from multiprocessing.queues import Queue
 import threading
 import weakref
 from functools import partial
 import itertools
+import sys
 import traceback
 
-# Workers are created as daemon threads and processes. This is done to allow the
-# interpreter to exit when there are still idle processes in a
-# ProcessPoolExecutor's process pool (i.e. shutdown() was not called). However,
-# allowing workers to die with the interpreter has two undesirable properties:
-#   - The workers would still be running during interpreter shutdown,
-#     meaning that they would fail in unpredictable ways.
-#   - The workers could be killed while evaluating a work item, which could
-#     be bad if the callable being evaluated has external side-effects e.g.
-#     writing to a file.
-#
-# To work around this problem, an exit handler is installed which tells the
-# workers to exit when their work queues are empty and then waits until the
-# threads/processes finish.
 
 _threads_wakeups = weakref.WeakKeyDictionary()
 _global_shutdown = False
@@ -79,18 +65,23 @@ _global_shutdown = False
 
 class _ThreadWakeup:
     def __init__(self):
+        self._closed = False
         self._reader, self._writer = mp.Pipe(duplex=False)
 
     def close(self):
-        self._writer.close()
+        if not self._closed:
-        self._reader.close()
+            self._closed = True
+            self._writer.close()
+            self._reader.close()
 
     def wakeup(self):
-        self._writer.send_bytes(b"")
+        if not self._closed:
+            self._writer.send_bytes(b"")
 
     def clear(self):
-        while self._reader.poll():
+        if not self._closed:
-            self._reader.recv_bytes()
+            while self._reader.poll():
+                self._reader.recv_bytes()
 
 
 def _python_exit():
@@ -98,10 +89,17 @@ def _python_exit():
     _global_shutdown = True
     items = list(_threads_wakeups.items())
     for _, thread_wakeup in items:
+        # call not protected by ProcessPoolExecutor._shutdown_lock
         thread_wakeup.wakeup()
     for t, _ in items:
         t.join()
 
+# Register for `_python_exit()` to be called just before joining all
+# non-daemon threads. This is used instead of `atexit.register()` for
+# compatibility with subinterpreters, which no longer support daemon threads.
+# See bpo-39812 for context.
+threading._register_atexit(_python_exit)
+
 # Controls how many more calls than processes will be queued in the call queue.
 # A smaller number will mean that processes spend more time idle waiting for
 # work while a larger number will make Future.cancel() succeed less frequently
@@ -109,6 +107,12 @@ def _python_exit():
 EXTRA_QUEUED_CALLS = 1
 
 
+# On Windows, WaitForMultipleObjects is used to wait for processes to finish.
+# It can wait on, at most, 63 objects. There is an overhead of two objects:
+# - the result queue reader
+# - the thread wakeup reader
+_MAX_WINDOWS_WORKERS = 63 - 2
+
 # Hack to embed stringification of remote traceback in local traceback
 
 class _RemoteTraceback(Exception):
@@ -122,6 +126,9 @@ class _ExceptionWithTraceback:
         tb = traceback.format_exception(type(exc), exc, tb)
         tb = ''.join(tb)
         self.exc = exc
+        # Traceback object needs to be garbage-collected as its frames
+        # contain references to all the objects in the exception scope
+        self.exc.__traceback__ = None
         self.tb = '\n"""\n%s"""' % tb
     def __reduce__(self):
         return _rebuild_exc, (self.exc, self.tb)
@@ -153,8 +160,11 @@ class _CallItem(object):
 
 class _SafeQueue(Queue):
     """Safe Queue set exception to the future object linked to a job"""
-    def __init__(self, max_size=0, *, ctx, pending_work_items):
+    def __init__(self, max_size=0, *, ctx, pending_work_items, shutdown_lock,
+                 thread_wakeup):
         self.pending_work_items = pending_work_items
+        self.shutdown_lock = shutdown_lock
+        self.thread_wakeup = thread_wakeup
         super().__init__(max_size, ctx=ctx)
 
     def _on_queue_feeder_error(self, e, obj):
@@ -162,8 +172,11 @@ class _SafeQueue(Queue):
             tb = traceback.format_exception(type(e), e, e.__traceback__)
             e.__cause__ = _RemoteTraceback('\n"""\n{}"""'.format(''.join(tb)))
             work_item = self.pending_work_items.pop(obj.work_id, None)
-            # work_item can be None if another process terminated. In this case,
+            with self.shutdown_lock:
-            # the queue_manager_thread fails all work_items with BrokenProcessPool
+                self.thread_wakeup.wakeup()
+            # work_item can be None if another process terminated. In this
+            # case, the executor_manager_thread fails all work_items
+            # with BrokenProcessPool
             if work_item is not None:
                 work_item.future.set_exception(e)
         else:
@@ -179,6 +192,7 @@ def _get_chunks(*iterables, chunksize):
             return
         yield chunk
 
+
 def _process_chunk(fn, chunk):
     """ Processes a chunk of an iterable passed to map.
 
@@ -235,126 +249,139 @@ def _process_worker(call_queue, result_queue, initializer, initargs):
             _sendback_result(result_queue, call_item.work_id, exception=exc)
         else:
             _sendback_result(result_queue, call_item.work_id, result=r)
+            del r
 
         # Liberate the resource as soon as possible, to avoid holding onto
         # open files or shared memory that is not needed anymore
         del call_item
 
 
-def _add_call_item_to_queue(pending_work_items,
+class _ExecutorManagerThread(threading.Thread):
-                            work_ids,
-                            call_queue):
-    """Fills call_queue with _WorkItems from pending_work_items.
-
-    This function never blocks.
-
-    Args:
-        pending_work_items: A dict mapping work ids to _WorkItems e.g.
-            {5: <_WorkItem...>, 6: <_WorkItem...>, ...}
-        work_ids: A queue.Queue of work ids e.g. Queue([5, 6, ...]). Work ids
-            are consumed and the corresponding _WorkItems from
-            pending_work_items are transformed into _CallItems and put in
-            call_queue.
-        call_queue: A multiprocessing.Queue that will be filled with _CallItems
-            derived from _WorkItems.
-    """
-    while True:
-        if call_queue.full():
-            return
-        try:
-            work_id = work_ids.get(block=False)
-        except queue.Empty:
-            return
-        else:
-            work_item = pending_work_items[work_id]
-
-            if work_item.future.set_running_or_notify_cancel():
-                call_queue.put(_CallItem(work_id,
-                                         work_item.fn,
-                                         work_item.args,
-                                         work_item.kwargs),
-                               block=True)
-            else:
-                del pending_work_items[work_id]
-                continue
-
-
-def _queue_management_worker(executor_reference,
-                             processes,
-                             pending_work_items,
-                             work_ids_queue,
-                             call_queue,
-                             result_queue,
-                             thread_wakeup):
     """Manages the communication between this process and the worker processes.
 
-    This function is run in a local thread.
+    The manager is run in a local thread.
 
     Args:
-        executor_reference: A weakref.ref to the ProcessPoolExecutor that owns
+        executor: A reference to the ProcessPoolExecutor that owns
-            this thread. Used to determine if the ProcessPoolExecutor has been
+            this thread. A weakref will be own by the manager as well as
-            garbage collected and that this function can exit.
+            references to internal objects used to introspect the state of
-        process: A list of the ctx.Process instances used as
+            the executor.
-            workers.
-        pending_work_items: A dict mapping work ids to _WorkItems e.g.
-            {5: <_WorkItem...>, 6: <_WorkItem...>, ...}
-        work_ids_queue: A queue.Queue of work ids e.g. Queue([5, 6, ...]).
-        call_queue: A ctx.Queue that will be filled with _CallItems
-            derived from _WorkItems for processing by the process workers.
-        result_queue: A ctx.SimpleQueue of _ResultItems generated by the
-            process workers.
-        thread_wakeup: A _ThreadWakeup to allow waking up the
-            queue_manager_thread from the main Thread and avoid deadlocks
-            caused by permanently locked queues.
     """
-    executor = None
 
-    def shutting_down():
+    def __init__(self, executor):
-        return (_global_shutdown or executor is None
+        # Store references to necessary internals of the executor.
-                or executor._shutdown_thread)
 
-    def shutdown_worker():
+        # A _ThreadWakeup to allow waking up the queue_manager_thread from the
-        # This is an upper bound on the number of children alive.
+        # main Thread and avoid deadlocks caused by permanently locked queues.
-        n_children_alive = sum(p.is_alive() for p in processes.values())
+        self.thread_wakeup = executor._executor_manager_thread_wakeup
-        n_children_to_stop = n_children_alive
+        self.shutdown_lock = executor._shutdown_lock
-        n_sentinels_sent = 0
-        # Send the right number of sentinels, to make sure all children are
-        # properly terminated.
-        while n_sentinels_sent < n_children_to_stop and n_children_alive > 0:
-            for i in range(n_children_to_stop - n_sentinels_sent):
-                try:
-                    call_queue.put_nowait(None)
-                    n_sentinels_sent += 1
-                except Full:
-                    break
-            n_children_alive = sum(p.is_alive() for p in processes.values())
 
-        # Release the queue's resources as soon as possible.
+        # A weakref.ref to the ProcessPoolExecutor that owns this thread. Used
-        call_queue.close()
+        # to determine if the ProcessPoolExecutor has been garbage collected
-        # If .join() is not called on the created processes then
+        # and that the manager can exit.
-        # some ctx.Queue methods may deadlock on Mac OS X.
+        # When the executor gets garbage collected, the weakref callback
-        for p in processes.values():
+        # will wake up the queue management thread so that it can terminate
-            p.join()
+        # if there is no pending work item.
+        def weakref_cb(_,
+                       thread_wakeup=self.thread_wakeup,
+                       shutdown_lock=self.shutdown_lock):
+            mp.util.debug('Executor collected: triggering callback for'
+                          ' QueueManager wakeup')
+            with shutdown_lock:
+                thread_wakeup.wakeup()
 
-    result_reader = result_queue._reader
+        self.executor_reference = weakref.ref(executor, weakref_cb)
-    wakeup_reader = thread_wakeup._reader
-    readers = [result_reader, wakeup_reader]
 
-    while True:
+        # A list of the ctx.Process instances used as workers.
-        _add_call_item_to_queue(pending_work_items,
+        self.processes = executor._processes
-                                work_ids_queue,
-                                call_queue)
 
+        # A ctx.Queue that will be filled with _CallItems derived from
+        # _WorkItems for processing by the process workers.
+        self.call_queue = executor._call_queue
+
+        # A ctx.SimpleQueue of _ResultItems generated by the process workers.
+        self.result_queue = executor._result_queue
+
+        # A queue.Queue of work ids e.g. Queue([5, 6, ...]).
+        self.work_ids_queue = executor._work_ids
+
+        # A dict mapping work ids to _WorkItems e.g.
+        #     {5: <_WorkItem...>, 6: <_WorkItem...>, ...}
+        self.pending_work_items = executor._pending_work_items
+
+        super().__init__()
+
+    def run(self):
+        # Main loop for the executor manager thread.
+
+        while True:
+            self.add_call_item_to_queue()
+
+            result_item, is_broken, cause = self.wait_result_broken_or_wakeup()
+
+            if is_broken:
+                self.terminate_broken(cause)
+                return
+            if result_item is not None:
+                self.process_result_item(result_item)
+                # Delete reference to result_item to avoid keeping references
+                # while waiting on new results.
+                del result_item
+
+                # attempt to increment idle process count
+                executor = self.executor_reference()
+                if executor is not None:
+                    executor._idle_worker_semaphore.release()
+                del executor
+
+            if self.is_shutting_down():
+                self.flag_executor_shutting_down()
+
+                # Since no new work items can be added, it is safe to shutdown
+                # this thread if there are no pending work items.
+                if not self.pending_work_items:
+                    self.join_executor_internals()
+                    return
+
+    def add_call_item_to_queue(self):
+        # Fills call_queue with _WorkItems from pending_work_items.
+        # This function never blocks.
+        while True:
+            if self.call_queue.full():
+                return
+            try:
+                work_id = self.work_ids_queue.get(block=False)
+            except queue.Empty:
+                return
+            else:
+                work_item = self.pending_work_items[work_id]
+
+                if work_item.future.set_running_or_notify_cancel():
+                    self.call_queue.put(_CallItem(work_id,
+                                                  work_item.fn,
+                                                  work_item.args,
+                                                  work_item.kwargs),
+                                        block=True)
+                else:
+                    del self.pending_work_items[work_id]
+                    continue
+
+    def wait_result_broken_or_wakeup(self):
         # Wait for a result to be ready in the result_queue while checking
         # that all worker processes are still running, or for a wake up
         # signal send. The wake up signals come either from new tasks being
         # submitted, from the executor being shutdown/gc-ed, or from the
         # shutdown of the python interpreter.
-        worker_sentinels = [p.sentinel for p in processes.values()]
+        result_reader = self.result_queue._reader
-        ready = wait(readers + worker_sentinels)
+        assert not self.thread_wakeup._closed
+        wakeup_reader = self.thread_wakeup._reader
+        readers = [result_reader, wakeup_reader]
+        worker_sentinels = [p.sentinel for p in list(self.processes.values())]
+        ready = mp.connection.wait(readers + worker_sentinels)
 
         cause = None
         is_broken = True
+        result_item = None
         if result_reader in ready:
             try:
                 result_item = result_reader.recv()
@@ -364,79 +391,138 @@ def _queue_management_worker(executor_reference,
 
         elif wakeup_reader in ready:
             is_broken = False
-            result_item = None
+
-        thread_wakeup.clear()
+        with self.shutdown_lock:
-        if is_broken:
+            self.thread_wakeup.clear()
-            # Mark the process pool broken so that submits fail right now.
+
-            executor = executor_reference()
+        return result_item, is_broken, cause
-            if executor is not None:
+
-                executor._broken = ('A child process terminated '
+    def process_result_item(self, result_item):
-                                    'abruptly, the process pool is not '
+        # Process the received a result_item. This can be either the PID of a
-                                    'usable anymore')
+        # worker that exited gracefully or a _ResultItem
-                executor._shutdown_thread = True
+
-                executor = None
-            bpe = BrokenProcessPool("A process in the process pool was "
-                                    "terminated abruptly while the future was "
-                                    "running or pending.")
-            if cause is not None:
-                bpe.__cause__ = _RemoteTraceback(
-                    f"\n'''\n{''.join(cause)}'''")
-            # All futures in flight must be marked failed
-            for work_id, work_item in pending_work_items.items():
-                work_item.future.set_exception(bpe)
-                # Delete references to object. See issue16284
-                del work_item
-            pending_work_items.clear()
-            # Terminate remaining workers forcibly: the queues or their
-            # locks may be in a dirty state and block forever.
-            for p in processes.values():
-                p.terminate()
-            shutdown_worker()
-            return
         if isinstance(result_item, int):
             # Clean shutdown of a worker using its PID
             # (avoids marking the executor broken)
-            assert shutting_down()
+            assert self.is_shutting_down()
-            p = processes.pop(result_item)
+            p = self.processes.pop(result_item)
             p.join()
-            if not processes:
+            if not self.processes:
-                shutdown_worker()
+                self.join_executor_internals()
                 return
-        elif result_item is not None:
+        else:
-            work_item = pending_work_items.pop(result_item.work_id, None)
+            # Received a _ResultItem so mark the future as completed.
+            work_item = self.pending_work_items.pop(result_item.work_id, None)
             # work_item can be None if another process terminated (see above)
             if work_item is not None:
                 if result_item.exception:
                     work_item.future.set_exception(result_item.exception)
                 else:
                     work_item.future.set_result(result_item.result)
-                # Delete references to object. See issue16284
-                del work_item
-            # Delete reference to result_item
-            del result_item
 
-        # Check whether we should start shutting down.
+    def is_shutting_down(self):
-        executor = executor_reference()
+        # Check whether we should start shutting down the executor.
+        executor = self.executor_reference()
         # No more work items can be added if:
         #   - The interpreter is shutting down OR
         #   - The executor that owns this worker has been collected OR
         #   - The executor that owns this worker has been shutdown.
-        if shutting_down():
+        return (_global_shutdown or executor is None
-            try:
+                or executor._shutdown_thread)
-                # Flag the executor as shutting down as early as possible if it
+
-                # is not gc-ed yet.
+    def terminate_broken(self, cause):
-                if executor is not None:
+        # Terminate the executor because it is in a broken state. The cause
-                    executor._shutdown_thread = True
+        # argument can be used to display more information on the error that
-                # Since no new work items can be added, it is safe to shutdown
+        # lead the executor into becoming broken.
-                # this thread if there are no pending work items.
+
-                if not pending_work_items:
+        # Mark the process pool broken so that submits fail right now.
-                    shutdown_worker()
+        executor = self.executor_reference()
-                    return
+        if executor is not None:
-            except Full:
+            executor._broken = ('A child process terminated '
-                # This is not a problem: we will eventually be woken up (in
+                                'abruptly, the process pool is not '
-                # result_queue.get()) and be able to send a sentinel again.
+                                'usable anymore')
-                pass
+            executor._shutdown_thread = True
-        executor = None
+            executor = None
+
+        # All pending tasks are to be marked failed with the following
+        # BrokenProcessPool error
+        bpe = BrokenProcessPool("A process in the process pool was "
+                                "terminated abruptly while the future was "
+                                "running or pending.")
+        if cause is not None:
+            bpe.__cause__ = _RemoteTraceback(
+                f"\n'''\n{''.join(cause)}'''")
+
+        # Mark pending tasks as failed.
+        for work_id, work_item in self.pending_work_items.items():
+            work_item.future.set_exception(bpe)
+            # Delete references to object. See issue16284
+            del work_item
+        self.pending_work_items.clear()
+
+        # Terminate remaining workers forcibly: the queues or their
+        # locks may be in a dirty state and block forever.
+        for p in self.processes.values():
+            p.terminate()
+
+        # clean up resources
+        self.join_executor_internals()
+
+    def flag_executor_shutting_down(self):
+        # Flag the executor as shutting down and cancel remaining tasks if
+        # requested as early as possible if it is not gc-ed yet.
+        executor = self.executor_reference()
+        if executor is not None:
+            executor._shutdown_thread = True
+            # Cancel pending work items if requested.
+            if executor._cancel_pending_futures:
+                # Cancel all pending futures and update pending_work_items
+                # to only have futures that are currently running.
+                new_pending_work_items = {}
+                for work_id, work_item in self.pending_work_items.items():
+                    if not work_item.future.cancel():
+                        new_pending_work_items[work_id] = work_item
+                self.pending_work_items = new_pending_work_items
+                # Drain work_ids_queue since we no longer need to
+                # add items to the call queue.
+                while True:
+                    try:
+                        self.work_ids_queue.get_nowait()
+                    except queue.Empty:
+                        break
+                # Make sure we do this only once to not waste time looping
+                # on running processes over and over.
+                executor._cancel_pending_futures = False
+
+    def shutdown_workers(self):
+        n_children_to_stop = self.get_n_children_alive()
+        n_sentinels_sent = 0
+        # Send the right number of sentinels, to make sure all children are
+        # properly terminated.
+        while (n_sentinels_sent < n_children_to_stop
+                and self.get_n_children_alive() > 0):
+            for i in range(n_children_to_stop - n_sentinels_sent):
+                try:
+                    self.call_queue.put_nowait(None)
+                    n_sentinels_sent += 1
+                except queue.Full:
+                    break
+
+    def join_executor_internals(self):
+        self.shutdown_workers()
+        # Release the queue's resources as soon as possible.
+        self.call_queue.close()
+        self.call_queue.join_thread()
+        with self.shutdown_lock:
+            self.thread_wakeup.close()
+        # If .join() is not called on the created processes then
+        # some ctx.Queue methods may deadlock on Mac OS X.
+        for p in self.processes.values():
+            p.join()
+
+    def get_n_children_alive(self):
+        # This is an upper bound on the number of children alive.
+        return sum(p.is_alive() for p in self.processes.values())
 
 
 _system_limits_checked = False
@@ -497,16 +583,23 @@ class ProcessPoolExecutor(_base.Executor):
                 worker processes will be created as the machine has processors.
             mp_context: A multiprocessing context to launch the workers. This
                 object should provide SimpleQueue, Queue and Process.
-            initializer: An callable used to initialize worker processes.
+            initializer: A callable used to initialize worker processes.
             initargs: A tuple of arguments to pass to the initializer.
         """
         _check_system_limits()
 
         if max_workers is None:
             self._max_workers = os.cpu_count() or 1
+            if sys.platform == 'win32':
+                self._max_workers = min(_MAX_WINDOWS_WORKERS,
+                                        self._max_workers)
         else:
             if max_workers <= 0:
                 raise ValueError("max_workers must be greater than 0")
+            elif (sys.platform == 'win32' and
+                max_workers > _MAX_WINDOWS_WORKERS):
+                raise ValueError(
+                    f"max_workers must be <= {_MAX_WINDOWS_WORKERS}")
 
             self._max_workers = max_workers
 
@@ -514,13 +607,17 @@ class ProcessPoolExecutor(_base.Executor):
             mp_context = mp.get_context()
         self._mp_context = mp_context
 
+        # https://github.com/python/cpython/issues/90622
+        self._safe_to_dynamically_spawn_children = (
+                self._mp_context.get_start_method(allow_none=False) != "fork")
+
         if initializer is not None and not callable(initializer):
             raise TypeError("initializer must be a callable")
         self._initializer = initializer
         self._initargs = initargs
 
         # Management thread
-        self._queue_management_thread = None
+        self._executor_manager_thread = None
 
         # Map of pids to processes
         self._processes = {}
@@ -528,9 +625,21 @@ class ProcessPoolExecutor(_base.Executor):
         # Shutdown is a two-step process.
         self._shutdown_thread = False
         self._shutdown_lock = threading.Lock()
+        self._idle_worker_semaphore = threading.Semaphore(0)
         self._broken = False
         self._queue_count = 0
         self._pending_work_items = {}
+        self._cancel_pending_futures = False
+
+        # _ThreadWakeup is a communication channel used to interrupt the wait
+        # of the main loop of executor_manager_thread from another thread (e.g.
+        # when calling executor.submit or executor.shutdown). We do not use the
+        # _result_queue to send wakeup signals to the executor_manager_thread
+        # as it could result in a deadlock if a worker process dies with the
+        # _result_queue write lock still acquired.
+        #
+        # _shutdown_lock must be locked to access _ThreadWakeup.
+        self._executor_manager_thread_wakeup = _ThreadWakeup()
 
         # Create communication channels for the executor
         # Make the call queue slightly larger than the number of processes to
@@ -539,7 +648,9 @@ class ProcessPoolExecutor(_base.Executor):
         queue_size = self._max_workers + EXTRA_QUEUED_CALLS
         self._call_queue = _SafeQueue(
             max_size=queue_size, ctx=self._mp_context,
-            pending_work_items=self._pending_work_items)
+            pending_work_items=self._pending_work_items,
+            shutdown_lock=self._shutdown_lock,
+            thread_wakeup=self._executor_manager_thread_wakeup)
         # Killed worker processes can produce spurious "broken pipe"
         # tracebacks in the queue's own worker thread. But we detect killed
         # processes anyway, so silence the tracebacks.
@@ -547,53 +658,50 @@ class ProcessPoolExecutor(_base.Executor):
         self._result_queue = mp_context.SimpleQueue()
         self._work_ids = queue.Queue()
 
-        # _ThreadWakeup is a communication channel used to interrupt the wait
+    def _start_executor_manager_thread(self):
-        # of the main loop of queue_manager_thread from another thread (e.g.
+        if self._executor_manager_thread is None:
-        # when calling executor.submit or executor.shutdown). We do not use the
-        # _result_queue to send the wakeup signal to the queue_manager_thread
-        # as it could result in a deadlock if a worker process dies with the
-        # _result_queue write lock still acquired.
-        self._queue_management_thread_wakeup = _ThreadWakeup()
-
-    def _start_queue_management_thread(self):
-        if self._queue_management_thread is None:
-            # When the executor gets garbarge collected, the weakref callback
-            # will wake up the queue management thread so that it can terminate
-            # if there is no pending work item.
-            def weakref_cb(_,
-                           thread_wakeup=self._queue_management_thread_wakeup):
-                mp.util.debug('Executor collected: triggering callback for'
-                              ' QueueManager wakeup')
-                thread_wakeup.wakeup()
             # Start the processes so that their sentinels are known.
-            self._adjust_process_count()
+            if not self._safe_to_dynamically_spawn_children:  # ie, using fork.
-            self._queue_management_thread = threading.Thread(
+                self._launch_processes()
-                target=_queue_management_worker,
+            self._executor_manager_thread = _ExecutorManagerThread(self)
-                args=(weakref.ref(self, weakref_cb),
+            self._executor_manager_thread.start()
-                      self._processes,
+            _threads_wakeups[self._executor_manager_thread] = \
-                      self._pending_work_items,
+                self._executor_manager_thread_wakeup
-                      self._work_ids,
-                      self._call_queue,
-                      self._result_queue,
-                      self._queue_management_thread_wakeup),
-                name="QueueManagerThread")
-            self._queue_management_thread.daemon = True
-            self._queue_management_thread.start()
-            _threads_wakeups[self._queue_management_thread] = \
-                self._queue_management_thread_wakeup
 
     def _adjust_process_count(self):
-        for _ in range(len(self._processes), self._max_workers):
+        # if there's an idle process, we don't need to spawn a new one.
-            p = self._mp_context.Process(
+        if self._idle_worker_semaphore.acquire(blocking=False):
-                target=_process_worker,
+            return
-                args=(self._call_queue,
-                      self._result_queue,
-                      self._initializer,
-                      self._initargs))
-            p.start()
-            self._processes[p.pid] = p
 
-    def submit(self, fn, *args, **kwargs):
+        process_count = len(self._processes)
+        if process_count < self._max_workers:
+            # Assertion disabled as this codepath is also used to replace a
+            # worker that unexpectedly dies, even when using the 'fork' start
+            # method. That means there is still a potential deadlock bug. If a
+            # 'fork' mp_context worker dies, we'll be forking a new one when
+            # we know a thread is running (self._executor_manager_thread).
+            #assert self._safe_to_dynamically_spawn_children or not self._executor_manager_thread, 'https://github.com/python/cpython/issues/90622'
+            self._spawn_process()
+
+    def _launch_processes(self):
+        # https://github.com/python/cpython/issues/90622
+        assert not self._executor_manager_thread, (
+                'Processes cannot be fork()ed after the thread has started, '
+                'deadlock in the child processes could result.')
+        for _ in range(len(self._processes), self._max_workers):
+            self._spawn_process()
+
+    def _spawn_process(self):
+        p = self._mp_context.Process(
+            target=_process_worker,
+            args=(self._call_queue,
+                  self._result_queue,
+                  self._initializer,
+                  self._initargs))
+        p.start()
+        self._processes[p.pid] = p
+
+    def submit(self, fn, /, *args, **kwargs):
         with self._shutdown_lock:
             if self._broken:
                 raise BrokenProcessPool(self._broken)
@@ -610,9 +718,11 @@ class ProcessPoolExecutor(_base.Executor):
             self._work_ids.put(self._queue_count)
             self._queue_count += 1
             # Wake up queue management thread
-            self._queue_management_thread_wakeup.wakeup()
+            self._executor_manager_thread_wakeup.wakeup()
 
-            self._start_queue_management_thread()
+            if self._safe_to_dynamically_spawn_children:
+                self._adjust_process_count()
+            self._start_executor_manager_thread()
             return f
     submit.__doc__ = _base.Executor.submit.__doc__
 
@@ -645,29 +755,24 @@ class ProcessPoolExecutor(_base.Executor):
                               timeout=timeout)
         return _chain_from_iterable_of_lists(results)
 
-    def shutdown(self, wait=True):
+    def shutdown(self, wait=True, *, cancel_futures=False):
         with self._shutdown_lock:
+            self._cancel_pending_futures = cancel_futures
             self._shutdown_thread = True
-        if self._queue_management_thread:
+            if self._executor_manager_thread_wakeup is not None:
-            # Wake up queue management thread
+                # Wake up queue management thread
-            self._queue_management_thread_wakeup.wakeup()
+                self._executor_manager_thread_wakeup.wakeup()
-            if wait:
+
-                self._queue_management_thread.join()
+        if self._executor_manager_thread is not None and wait:
+            self._executor_manager_thread.join()
         # To reduce the risk of opening too many files, remove references to
         # objects that use file descriptors.
-        self._queue_management_thread = None
+        self._executor_manager_thread = None
-        if self._call_queue is not None:
+        self._call_queue = None
-            self._call_queue.close()
+        if self._result_queue is not None and wait:
-            if wait:
+            self._result_queue.close()
-                self._call_queue.join_thread()
-            self._call_queue = None
         self._result_queue = None
         self._processes = None
-
+        self._executor_manager_thread_wakeup = None
-        if self._queue_management_thread_wakeup:
-            self._queue_management_thread_wakeup.close()
-            self._queue_management_thread_wakeup = None
 
     shutdown.__doc__ = _base.Executor.shutdown.__doc__
-
-atexit.register(_python_exit)

extlib/Python/Lib/concurrent/futures/thread.py

@@ -5,41 +5,42 @@
 
 __author__ = 'Brian Quinlan (brian@sweetapp.com)'
 
-import atexit
 from concurrent.futures import _base
 import itertools
 import queue
 import threading
+import types
 import weakref
 import os
 
-# Workers are created as daemon threads. This is done to allow the interpreter
-# to exit when there are still idle threads in a ThreadPoolExecutor's thread
-# pool (i.e. shutdown() was not called). However, allowing workers to die with
-# the interpreter has two undesirable properties:
-#   - The workers would still be running during interpreter shutdown,
-#     meaning that they would fail in unpredictable ways.
-#   - The workers could be killed while evaluating a work item, which could
-#     be bad if the callable being evaluated has external side-effects e.g.
-#     writing to a file.
-#
-# To work around this problem, an exit handler is installed which tells the
-# workers to exit when their work queues are empty and then waits until the
-# threads finish.
 
 _threads_queues = weakref.WeakKeyDictionary()
 _shutdown = False
+# Lock that ensures that new workers are not created while the interpreter is
+# shutting down. Must be held while mutating _threads_queues and _shutdown.
+_global_shutdown_lock = threading.Lock()
 
 def _python_exit():
     global _shutdown
-    _shutdown = True
+    with _global_shutdown_lock:
+        _shutdown = True
     items = list(_threads_queues.items())
     for t, q in items:
         q.put(None)
     for t, q in items:
         t.join()
 
-atexit.register(_python_exit)
+# Register for `_python_exit()` to be called just before joining all
+# non-daemon threads. This is used instead of `atexit.register()` for
+# compatibility with subinterpreters, which no longer support daemon threads.
+# See bpo-39812 for context.
+threading._register_atexit(_python_exit)
+
+# At fork, reinitialize the `_global_shutdown_lock` lock in the child process
+if hasattr(os, 'register_at_fork'):
+    os.register_at_fork(before=_global_shutdown_lock.acquire,
+                        after_in_child=_global_shutdown_lock._at_fork_reinit,
+                        after_in_parent=_global_shutdown_lock.release)
 
 
 class _WorkItem(object):
@@ -62,6 +63,8 @@ class _WorkItem(object):
         else:
             self.future.set_result(result)
 
+    __class_getitem__ = classmethod(types.GenericAlias)
+
 
 def _worker(executor_reference, work_queue, initializer, initargs):
     if initializer is not None:
@@ -80,7 +83,14 @@ def _worker(executor_reference, work_queue, initializer, initargs):
                 work_item.run()
                 # Delete references to object. See issue16284
                 del work_item
+
+                # attempt to increment idle count
+                executor = executor_reference()
+                if executor is not None:
+                    executor._idle_semaphore.release()
+                del executor
                 continue
+
             executor = executor_reference()
             # Exit if:
             #   - The interpreter is shutting down OR
@@ -118,13 +128,18 @@ class ThreadPoolExecutor(_base.Executor):
             max_workers: The maximum number of threads that can be used to
                 execute the given calls.
             thread_name_prefix: An optional name prefix to give our threads.
-            initializer: An callable used to initialize worker threads.
+            initializer: A callable used to initialize worker threads.
             initargs: A tuple of arguments to pass to the initializer.
         """
         if max_workers is None:
-            # Use this number because ThreadPoolExecutor is often
+            # ThreadPoolExecutor is often used to:
-            # used to overlap I/O instead of CPU work.
+            # * CPU bound task which releases GIL
-            max_workers = (os.cpu_count() or 1) * 5
+            # * I/O bound task (which releases GIL, of course)
+            #
+            # We use cpu_count + 4 for both types of tasks.
+            # But we limit it to 32 to avoid consuming surprisingly large resource
+            # on many core machine.
+            max_workers = min(32, (os.cpu_count() or 1) + 4)
         if max_workers <= 0:
             raise ValueError("max_workers must be greater than 0")
 
@@ -133,6 +148,7 @@ class ThreadPoolExecutor(_base.Executor):
 
         self._max_workers = max_workers
         self._work_queue = queue.SimpleQueue()
+        self._idle_semaphore = threading.Semaphore(0)
         self._threads = set()
         self._broken = False
         self._shutdown = False
@@ -142,15 +158,15 @@ class ThreadPoolExecutor(_base.Executor):
         self._initializer = initializer
         self._initargs = initargs
 
-    def submit(self, fn, *args, **kwargs):
+    def submit(self, fn, /, *args, **kwargs):
-        with self._shutdown_lock:
+        with self._shutdown_lock, _global_shutdown_lock:
             if self._broken:
                 raise BrokenThreadPool(self._broken)
 
             if self._shutdown:
                 raise RuntimeError('cannot schedule new futures after shutdown')
             if _shutdown:
-                raise RuntimeError('cannot schedule new futures after'
+                raise RuntimeError('cannot schedule new futures after '
                                    'interpreter shutdown')
 
             f = _base.Future()
@@ -162,12 +178,15 @@ class ThreadPoolExecutor(_base.Executor):
     submit.__doc__ = _base.Executor.submit.__doc__
 
     def _adjust_thread_count(self):
+        # if idle threads are available, don't spin new threads
+        if self._idle_semaphore.acquire(timeout=0):
+            return
+
         # When the executor gets lost, the weakref callback will wake up
         # the worker threads.
         def weakref_cb(_, q=self._work_queue):
             q.put(None)
-        # TODO(bquinlan): Should avoid creating new threads if there are more
+
-        # idle threads than items in the work queue.
         num_threads = len(self._threads)
         if num_threads < self._max_workers:
             thread_name = '%s_%d' % (self._thread_name_prefix or self,
@@ -177,7 +196,6 @@ class ThreadPoolExecutor(_base.Executor):
                                        self._work_queue,
                                        self._initializer,
                                        self._initargs))
-            t.daemon = True
             t.start()
             self._threads.add(t)
             _threads_queues[t] = self._work_queue
@@ -195,9 +213,22 @@ class ThreadPoolExecutor(_base.Executor):
                 if work_item is not None:
                     work_item.future.set_exception(BrokenThreadPool(self._broken))
 
-    def shutdown(self, wait=True):
+    def shutdown(self, wait=True, *, cancel_futures=False):
         with self._shutdown_lock:
             self._shutdown = True
+            if cancel_futures:
+                # Drain all work items from the queue, and then cancel their
+                # associated futures.
+                while True:
+                    try:
+                        work_item = self._work_queue.get_nowait()
+                    except queue.Empty:
+                        break
+                    if work_item is not None:
+                        work_item.future.cancel()
+
+            # Send a wake-up to prevent threads calling
+            # _work_queue.get(block=True) from permanently blocking.
             self._work_queue.put(None)
         if wait:
             for t in self._threads:

extlib/Python/Lib/configparser.py

@@ -56,7 +56,7 @@ ConfigParser -- responsible for parsing a list of
 
         When `interpolation` is given, it should be an Interpolation subclass
         instance. It will be used as the handler for option value
-        pre-processing when using getters. RawConfigParser object s don't do
+        pre-processing when using getters. RawConfigParser objects don't do
         any sort of interpolation, whereas ConfigParser uses an instance of
         BasicInterpolation. The library also provides a ``zc.buildbot``
         inspired ExtendedInterpolation implementation.
@@ -80,7 +80,7 @@ ConfigParser -- responsible for parsing a list of
         Return list of configuration options for the named section.
 
     read(filenames, encoding=None)
-        Read and parse the list of named configuration files, given by
+        Read and parse the iterable of named configuration files, given by
         name.  A single filename is also allowed.  Non-existing files
         are ignored.  Return list of successfully read files.
 
@@ -139,7 +139,7 @@ ConfigParser -- responsible for parsing a list of
 """
 
 from collections.abc import MutableMapping
-from collections import OrderedDict as _default_dict, ChainMap as _ChainMap
+from collections import ChainMap as _ChainMap
 import functools
 import io
 import itertools
@@ -157,6 +157,7 @@ __all__ = ["NoSectionError", "DuplicateOptionError", "DuplicateSectionError",
            "LegacyInterpolation", "SectionProxy", "ConverterMapping",
            "DEFAULTSECT", "MAX_INTERPOLATION_DEPTH"]
 
+_default_dict = dict
 DEFAULTSECT = "DEFAULT"
 
 MAX_INTERPOLATION_DEPTH = 10
@@ -676,13 +677,13 @@ class RawConfigParser(MutableMapping):
         return list(opts.keys())
 
     def read(self, filenames, encoding=None):
-        """Read and parse a filename or a list of filenames.
+        """Read and parse a filename or an iterable of filenames.
 
         Files that cannot be opened are silently ignored; this is
-        designed so that you can specify a list of potential
+        designed so that you can specify an iterable of potential
         configuration file locations (e.g. current directory, user's
         home directory, systemwide directory), and all existing
-        configuration files in the list will be read.  A single
+        configuration files in the iterable will be read.  A single
         filename may also be given.
 
         Return list of successfully read files.
@@ -846,6 +847,7 @@ class RawConfigParser(MutableMapping):
         except KeyError:
             if section != self.default_section:
                 raise NoSectionError(section)
+        orig_keys = list(d.keys())
         # Update with the entry specific variables
         if vars:
             for key, value in vars.items():
@@ -854,7 +856,7 @@ class RawConfigParser(MutableMapping):
             section, option, d[option], d)
         if raw:
             value_getter = lambda option: d[option]
-        return [(option, value_getter(option)) for option in d.keys()]
+        return [(option, value_getter(option)) for option in orig_keys]
 
     def popitem(self):
         """Remove a section from the parser and return it as
@@ -905,6 +907,9 @@ class RawConfigParser(MutableMapping):
 
         If `space_around_delimiters' is True (the default), delimiters
         between keys and values are surrounded by spaces.
+
+        Please note that comments in the original configuration file are not
+        preserved when writing the configuration back.
         """
         if space_around_delimiters:
             d = " {} ".format(self._delimiters[0])
@@ -961,7 +966,8 @@ class RawConfigParser(MutableMapping):
     def __setitem__(self, key, value):
         # To conform with the mapping protocol, overwrites existing values in
         # the section.
-
+        if key in self and self[key] is value:
+            return
         # XXX this is not atomic if read_dict fails at any point. Then again,
         # no update method in configparser is atomic in this implementation.
         if key == self.default_section:
@@ -1002,7 +1008,7 @@ class RawConfigParser(MutableMapping):
         Configuration files may include comments, prefixed by specific
         characters (`#' and `;' by default). Comments may appear on their own
         in an otherwise empty line or may be entered in lines holding values or
-        section names.
+        section names. Please note that comments get stripped off when reading configuration files.
         """
         elements_added = set()
         cursect = None                        # None, or a dictionary

extlib/Python/Lib/contextlib.py

@@ -4,6 +4,7 @@ import sys
 import _collections_abc
 from collections import deque
 from functools import wraps
+from types import MethodType, GenericAlias
 
 __all__ = ["asynccontextmanager", "contextmanager", "closing", "nullcontext",
            "AbstractContextManager", "AbstractAsyncContextManager",
@@ -15,6 +16,8 @@ class AbstractContextManager(abc.ABC):
 
     """An abstract base class for context managers."""
 
+    __class_getitem__ = classmethod(GenericAlias)
+
     def __enter__(self):
         """Return `self` upon entering the runtime context."""
         return self
@@ -35,6 +38,8 @@ class AbstractAsyncContextManager(abc.ABC):
 
     """An abstract base class for asynchronous context managers."""
 
+    __class_getitem__ = classmethod(GenericAlias)
+
     async def __aenter__(self):
         """Return `self` upon entering the runtime context."""
         return self
@@ -92,18 +97,20 @@ class _GeneratorContextManagerBase:
         # for the class instead.
         # See http://bugs.python.org/issue19404 for more details.
 
-
-class _GeneratorContextManager(_GeneratorContextManagerBase,
-                               AbstractContextManager,
-                               ContextDecorator):
-    """Helper for @contextmanager decorator."""
-
     def _recreate_cm(self):
-        # _GCM instances are one-shot context managers, so the
+        # _GCMB instances are one-shot context managers, so the
         # CM must be recreated each time a decorated function is
         # called
         return self.__class__(self.func, self.args, self.kwds)
 
+
+class _GeneratorContextManager(
+    _GeneratorContextManagerBase,
+    AbstractContextManager,
+    ContextDecorator,
+):
+    """Helper for @contextmanager decorator."""
+
     def __enter__(self):
         # do not keep args and kwds alive unnecessarily
         # they are only needed for recreation, which is not possible anymore
@@ -113,8 +120,8 @@ class _GeneratorContextManager(_GeneratorContextManagerBase,
         except StopIteration:
             raise RuntimeError("generator didn't yield") from None
 
-    def __exit__(self, type, value, traceback):
+    def __exit__(self, typ, value, traceback):
-        if type is None:
+        if typ is None:
             try:
                 next(self.gen)
             except StopIteration:
@@ -125,9 +132,9 @@ class _GeneratorContextManager(_GeneratorContextManagerBase,
             if value is None:
                 # Need to force instantiation so we can reliably
                 # tell if we get the same exception back
-                value = type()
+                value = typ()
             try:
-                self.gen.throw(type, value, traceback)
+                self.gen.throw(typ, value, traceback)
             except StopIteration as exc:
                 # Suppress StopIteration *unless* it's the same exception that
                 # was passed to throw().  This prevents a StopIteration
@@ -137,35 +144,39 @@ class _GeneratorContextManager(_GeneratorContextManagerBase,
                 # Don't re-raise the passed in exception. (issue27122)
                 if exc is value:
                     return False
-                # Likewise, avoid suppressing if a StopIteration exception
+                # Avoid suppressing if a StopIteration exception
                 # was passed to throw() and later wrapped into a RuntimeError
-                # (see PEP 479).
+                # (see PEP 479 for sync generators; async generators also
-                if type is StopIteration and exc.__cause__ is value:
+                # have this behavior). But do this only if the exception wrapped
+                # by the RuntimeError is actually Stop(Async)Iteration (see
+                # issue29692).
+                if (
+                    isinstance(value, StopIteration)
+                    and exc.__cause__ is value
+                ):
                     return False
                 raise
-            except:
+            except BaseException as exc:
                 # only re-raise if it's *not* the exception that was
                 # passed to throw(), because __exit__() must not raise
                 # an exception unless __exit__() itself failed.  But throw()
                 # has to raise the exception to signal propagation, so this
                 # fixes the impedance mismatch between the throw() protocol
                 # and the __exit__() protocol.
-                #
+                if exc is not value:
-                # This cannot use 'except BaseException as exc' (as in the
+                    raise
-                # async implementation) to maintain compatibility with
+                return False
-                # Python 2, where old-style class exceptions are not caught
-                # by 'except BaseException'.
-                if sys.exc_info()[1] is value:
-                    return False
-                raise
             raise RuntimeError("generator didn't stop after throw()")
 
 
 class _AsyncGeneratorContextManager(_GeneratorContextManagerBase,
                                     AbstractAsyncContextManager):
-    """Helper for @asynccontextmanager."""
+    """Helper for @asynccontextmanager decorator."""
 
     async def __aenter__(self):
+        # do not keep args and kwds alive unnecessarily
+        # they are only needed for recreation, which is not possible anymore
+        del self.args, self.kwds, self.func
         try:
             return await self.gen.__anext__()
         except StopAsyncIteration:
@@ -176,35 +187,48 @@ class _AsyncGeneratorContextManager(_GeneratorContextManagerBase,
             try:
                 await self.gen.__anext__()
             except StopAsyncIteration:
-                return
+                return False
             else:
                 raise RuntimeError("generator didn't stop")
         else:
             if value is None:
+                # Need to force instantiation so we can reliably
+                # tell if we get the same exception back
                 value = typ()
-            # See _GeneratorContextManager.__exit__ for comments on subtleties
-            # in this implementation
             try:
                 await self.gen.athrow(typ, value, traceback)
-                raise RuntimeError("generator didn't stop after throw()")
             except StopAsyncIteration as exc:
+                # Suppress StopIteration *unless* it's the same exception that
+                # was passed to throw().  This prevents a StopIteration
+                # raised inside the "with" statement from being suppressed.
                 return exc is not value
             except RuntimeError as exc:
+                # Don't re-raise the passed in exception. (issue27122)
                 if exc is value:
                     return False
-                # Avoid suppressing if a StopIteration exception
+                # Avoid suppressing if a Stop(Async)Iteration exception
-                # was passed to throw() and later wrapped into a RuntimeError
+                # was passed to athrow() and later wrapped into a RuntimeError
                 # (see PEP 479 for sync generators; async generators also
                 # have this behavior). But do this only if the exception wrapped
                 # by the RuntimeError is actully Stop(Async)Iteration (see
                 # issue29692).
-                if isinstance(value, (StopIteration, StopAsyncIteration)):
+                if (
-                    if exc.__cause__ is value:
+                    isinstance(value, (StopIteration, StopAsyncIteration))
-                        return False
+                    and exc.__cause__ is value
+                ):
+                    return False
                 raise
             except BaseException as exc:
+                # only re-raise if it's *not* the exception that was
+                # passed to throw(), because __exit__() must not raise
+                # an exception unless __exit__() itself failed.  But throw()
+                # has to raise the exception to signal propagation, so this
+                # fixes the impedance mismatch between the throw() protocol
+                # and the __exit__() protocol.
                 if exc is not value:
                     raise
+                return False
+            raise RuntimeError("generator didn't stop after athrow()")
 
 
 def contextmanager(func):
@@ -373,12 +397,10 @@ class _BaseExitStack:
 
     @staticmethod
     def _create_exit_wrapper(cm, cm_exit):
-        def _exit_wrapper(exc_type, exc, tb):
+        return MethodType(cm_exit, cm)
-            return cm_exit(cm, exc_type, exc, tb)
-        return _exit_wrapper
 
     @staticmethod
-    def _create_cb_wrapper(callback, *args, **kwds):
+    def _create_cb_wrapper(callback, /, *args, **kwds):
         def _exit_wrapper(exc_type, exc, tb):
             callback(*args, **kwds)
         return _exit_wrapper
@@ -427,7 +449,7 @@ class _BaseExitStack:
         self._push_cm_exit(cm, _exit)
         return result
 
-    def callback(self, callback, *args, **kwds):
+    def callback(self, callback, /, *args, **kwds):
         """Registers an arbitrary callback and arguments.
 
         Cannot suppress exceptions.
@@ -443,7 +465,6 @@ class _BaseExitStack:
     def _push_cm_exit(self, cm, cm_exit):
         """Helper to correctly register callbacks to __exit__ methods."""
         _exit_wrapper = self._create_exit_wrapper(cm, cm_exit)
-        _exit_wrapper.__self__ = cm
         self._push_exit_callback(_exit_wrapper, True)
 
     def _push_exit_callback(self, callback, is_sync=True):
@@ -475,10 +496,10 @@ class ExitStack(_BaseExitStack, AbstractContextManager):
             # Context may not be correct, so find the end of the chain
             while 1:
                 exc_context = new_exc.__context__
-                if exc_context is old_exc:
+                if exc_context is None or exc_context is old_exc:
                     # Context is already set correctly (see issue 20317)
                     return
-                if exc_context is None or exc_context is frame_exc:
+                if exc_context is frame_exc:
                     break
                 new_exc = exc_context
             # Change the end of the chain to point to the exception
@@ -535,12 +556,10 @@ class AsyncExitStack(_BaseExitStack, AbstractAsyncContextManager):
 
     @staticmethod
     def _create_async_exit_wrapper(cm, cm_exit):
-        async def _exit_wrapper(exc_type, exc, tb):
+        return MethodType(cm_exit, cm)
-            return await cm_exit(cm, exc_type, exc, tb)
-        return _exit_wrapper
 
     @staticmethod
-    def _create_async_cb_wrapper(callback, *args, **kwds):
+    def _create_async_cb_wrapper(callback, /, *args, **kwds):
         async def _exit_wrapper(exc_type, exc, tb):
             await callback(*args, **kwds)
         return _exit_wrapper
@@ -575,7 +594,7 @@ class AsyncExitStack(_BaseExitStack, AbstractAsyncContextManager):
             self._push_async_cm_exit(exit, exit_method)
         return exit  # Allow use as a decorator
 
-    def push_async_callback(self, callback, *args, **kwds):
+    def push_async_callback(self, callback, /, *args, **kwds):
         """Registers an arbitrary coroutine function and arguments.
 
         Cannot suppress exceptions.
@@ -596,7 +615,6 @@ class AsyncExitStack(_BaseExitStack, AbstractAsyncContextManager):
         """Helper to correctly register coroutine function to __aexit__
         method."""
         _exit_wrapper = self._create_async_exit_wrapper(cm, cm_exit)
-        _exit_wrapper.__self__ = cm
         self._push_exit_callback(_exit_wrapper, False)
 
     async def __aenter__(self):
@@ -612,10 +630,10 @@ class AsyncExitStack(_BaseExitStack, AbstractAsyncContextManager):
             # Context may not be correct, so find the end of the chain
             while 1:
                 exc_context = new_exc.__context__
-                if exc_context is old_exc:
+                if exc_context is None or exc_context is old_exc:
                     # Context is already set correctly (see issue 20317)
                     return
-                if exc_context is None or exc_context is frame_exc:
+                if exc_context is frame_exc:
                     break
                 new_exc = exc_context
             # Change the end of the chain to point to the exception

extlib/Python/Lib/copy.py

@@ -39,8 +39,8 @@ Python's deep copy operation avoids these problems by:
     set of components copied
 
 This version does not copy types like module, class, function, method,
-nor stack trace, stack frame, nor file, socket, window, nor array, nor
+nor stack trace, stack frame, nor file, socket, window, nor any
-any similar types.
+similar types.
 
 Classes can use the same interfaces to control copying that they use
 to control pickling: they can define methods called __getinitargs__(),
@@ -75,24 +75,20 @@ def copy(x):
     if copier:
         return copier(x)
 
-    try:
+    if issubclass(cls, type):
-        issc = issubclass(cls, type)
-    except TypeError: # cls is not a class
-        issc = False
-    if issc:
         # treat it as a regular class:
         return _copy_immutable(x)
 
     copier = getattr(cls, "__copy__", None)
-    if copier:
+    if copier is not None:
         return copier(x)
 
     reductor = dispatch_table.get(cls)
-    if reductor:
+    if reductor is not None:
         rv = reductor(x)
     else:
         reductor = getattr(x, "__reduce_ex__", None)
-        if reductor:
+        if reductor is not None:
             rv = reductor(4)
         else:
             reductor = getattr(x, "__reduce__", None)
@@ -111,7 +107,7 @@ _copy_dispatch = d = {}
 def _copy_immutable(x):
     return x
 for t in (type(None), int, float, bool, complex, str, tuple,
-          bytes, frozenset, type, range, slice,
+          bytes, frozenset, type, range, slice, property,
           types.BuiltinFunctionType, type(Ellipsis), type(NotImplemented),
           types.FunctionType, weakref.ref):
     d[t] = _copy_immutable
@@ -146,18 +142,14 @@ def deepcopy(x, memo=None, _nil=[]):
     cls = type(x)
 
     copier = _deepcopy_dispatch.get(cls)
-    if copier:
+    if copier is not None:
         y = copier(x, memo)
     else:
-        try:
+        if issubclass(cls, type):
-            issc = issubclass(cls, type)
-        except TypeError: # cls is not a class (old Boost; see SF #502085)
-            issc = 0
-        if issc:
             y = _deepcopy_atomic(x, memo)
         else:
             copier = getattr(x, "__deepcopy__", None)
-            if copier:
+            if copier is not None:
                 y = copier(memo)
             else:
                 reductor = dispatch_table.get(cls)
@@ -165,7 +157,7 @@ def deepcopy(x, memo=None, _nil=[]):
                     rv = reductor(x)
                 else:
                     reductor = getattr(x, "__reduce_ex__", None)
-                    if reductor:
+                    if reductor is not None:
                         rv = reductor(4)
                     else:
                         reductor = getattr(x, "__reduce__", None)
@@ -198,14 +190,12 @@ d[bool] = _deepcopy_atomic
 d[complex] = _deepcopy_atomic
 d[bytes] = _deepcopy_atomic
 d[str] = _deepcopy_atomic
-try:
+d[types.CodeType] = _deepcopy_atomic
-    d[types.CodeType] = _deepcopy_atomic
-except AttributeError:
-    pass
 d[type] = _deepcopy_atomic
 d[types.BuiltinFunctionType] = _deepcopy_atomic
 d[types.FunctionType] = _deepcopy_atomic
 d[weakref.ref] = _deepcopy_atomic
+d[property] = _deepcopy_atomic
 
 def _deepcopy_list(x, memo, deepcopy=deepcopy):
     y = []

extlib/Python/Lib/copyreg.py

@@ -48,29 +48,36 @@ def _reconstructor(cls, base, state):
     return obj
 
 _HEAPTYPE = 1<<9
+_new_type = type(int.__new__)
 
 # Python code for object.__reduce_ex__ for protocols 0 and 1
 
 def _reduce_ex(self, proto):
     assert proto < 2
-    for base in self.__class__.__mro__:
+    cls = self.__class__
+    for base in cls.__mro__:
         if hasattr(base, '__flags__') and not base.__flags__ & _HEAPTYPE:
             break
+        new = base.__new__
+        if isinstance(new, _new_type) and new.__self__ is base:
+            break
     else:
         base = object # not really reachable
     if base is object:
         state = None
     else:
-        if base is self.__class__:
+        if base is cls:
-            raise TypeError("can't pickle %s objects" % base.__name__)
+            raise TypeError(f"cannot pickle {cls.__name__!r} object")
         state = base(self)
-    args = (self.__class__, base, state)
+    args = (cls, base, state)
     try:
         getstate = self.__getstate__
     except AttributeError:
         if getattr(self, "__slots__", None):
-            raise TypeError("a class that defines __slots__ without "
+            raise TypeError(f"cannot pickle {cls.__name__!r} object: "
-                            "defining __getstate__ cannot be pickled") from None
+                            f"a class that defines __slots__ without "
+                            f"defining __getstate__ cannot be pickled "
+                            f"with protocol {proto}") from None
         try:
             dict = self.__dict__
         except AttributeError:

extlib/Python/Lib/crypt.py

@@ -1,6 +1,16 @@
 """Wrapper to the POSIX crypt library call and associated functionality."""
 
-import _crypt
+import sys as _sys
+
+try:
+    import _crypt
+except ModuleNotFoundError:
+    if _sys.platform == 'win32':
+        raise ImportError("The crypt module is not supported on Windows")
+    else:
+        raise ImportError("The required _crypt module was not built as part of CPython")
+
+import errno
 import string as _string
 from random import SystemRandom as _SystemRandom
 from collections import namedtuple as _namedtuple
@@ -79,7 +89,14 @@ def _add_method(name, *args, rounds=None):
     method = _Method(name, *args)
     globals()['METHOD_' + name] = method
     salt = mksalt(method, rounds=rounds)
-    result = crypt('', salt)
+    result = None
+    try:
+        result = crypt('', salt)
+    except OSError as e:
+        # Not all libc libraries support all encryption methods.
+        if e.errno == errno.EINVAL:
+            return False
+        raise
     if result and len(result) == method.total_size:
         methods.append(method)
         return True