3.15.0a1 - Cpython — ContextQMD

.. date: 2025-10-14-00-17-48 .. gh-issue: 115119 .. nonce: 470I1N .. release date: 2025-10-14 .. section: macOS

Update macOS installer to use libmpdecimal 4.0.1.

.. date: 2025-10-14-00-08-16 .. gh-issue: 124111 .. nonce: 7-j-DQ .. section: macOS

Update macOS installer to use Tcl/Tk 9.0.2.

.. date: 2025-10-13-23-46-12 .. gh-issue: 132339 .. nonce: kAp603 .. section: macOS

Update macOS installer version of OpenSSL to 3.5.4.

.. date: 2025-08-06-06-29-12 .. gh-issue: 137450 .. nonce: JZypb7 .. section: macOS

macOS installer shell path management improvements: separate the installer Shell profile updater postinstall script from the Update Shell Profile.command to enable more robust error handling.

.. date: 2025-07-27-02-17-40 .. gh-issue: 137134 .. nonce: pjgITs .. section: macOS

Update macOS installer to ship with SQLite version 3.50.4.

.. date: 2025-10-08-22-54-38 .. gh-issue: 139810 .. nonce: LAaemi .. section: Windows

Installing with py install 3[.x]-dev will now select final versions as well as prereleases.

.. date: 2025-10-04-12-18-45 .. gh-issue: 139573 .. nonce: EO9kVB .. section: Windows

Updated bundled version of OpenSSL to 3.0.18.

.. date: 2025-09-15-15-34-29 .. gh-issue: 138896 .. nonce: lkiF_7 .. section: Windows

Fix error installing C runtime on non-updated Windows machines

.. date: 2025-09-03-01-07-44 .. gh-issue: 138314 .. nonce: IeWQ2i .. section: Windows

Add :func:winreg.DeleteTree.

.. date: 2025-07-27-14-25-11 .. gh-issue: 137136 .. nonce: xNthFT .. section: Windows

Suppress build warnings when build on Windows with --experimental-jit-interpreter.

.. date: 2025-07-27-02-16-53 .. gh-issue: 137134 .. nonce: W0WpDF .. section: Windows

Update Windows installer to ship with SQLite 3.50.4.

.. date: 2025-06-03-18-26-54 .. gh-issue: 135099 .. nonce: Q9usKm .. section: Windows

Fix a crash that could occur on Windows when a background thread waits on a :c:type:PyMutex while the main thread is shutting down the interpreter.

.. date: 2025-05-20-21-43-20 .. gh-issue: 130727 .. nonce: -69t4D .. section: Windows

Fix a race in internal calls into WMI that can result in an "invalid handle" exception under high load. Patch by Chris Eibl.

.. date: 2025-05-19-03-02-04 .. gh-issue: 76023 .. nonce: vHOf6M .. section: Windows

Make :func:os.path.realpath ignore Windows error 1005 when in non-strict mode.

.. date: 2025-05-13-13-25-27 .. gh-issue: 133779 .. nonce: -YcTBz .. section: Windows

Reverts the change to generate different :file:pyconfig.h files based on compiler settings, as it was frequently causing extension builds to break. In particular, the Py_GIL_DISABLED preprocessor variable must now always be defined explicitly when compiling for the experimental free-threaded runtime. The :func:sysconfig.get_config_var function can be used to determine whether the current runtime was compiled with that flag or not.

.. date: 2025-05-08-19-07-26 .. gh-issue: 133626 .. nonce: yFTKYK .. section: Windows

Ensures packages are not accidentally bundled into the traditional installer.

.. date: 2025-05-07-13-04-22 .. gh-issue: 133580 .. nonce: jBMujJ .. section: Windows

Fix :func:sys.getwindowsversion failing without setting an exception when called on some WinAPI partitions.

.. date: 2025-05-07-11-45-30 .. gh-issue: 133572 .. nonce: Xc2zxH .. section: Windows

Avoid LsaNtStatus to WinError conversion on unsupported WinAPI partitions.

.. date: 2025-05-07-11-25-29 .. gh-issue: 133568 .. nonce: oYV0d8 .. section: Windows

Fix compile error when using a WinAPI partition that doesn't support the RPC runtime library.

.. date: 2025-05-07-09-02-19 .. gh-issue: 133562 .. nonce: lqqNW1 .. section: Windows

Disable handling of security descriptors by :func:os.mkdir with mode 0o700 on WinAPI partitions that do not support it. This only affects custom builds for specialized targets.

.. date: 2025-05-07-08-19-15 .. gh-issue: 133537 .. nonce: yzf963 .. section: Windows

Avoid using console I/O in WinAPI partitions that don’t support it

.. date: 2025-03-31-15-37-57 .. gh-issue: 131942 .. nonce: jip_aL .. section: Windows

Use the Python-specific :c:macro:Py_DEBUG macro rather than :c:macro:!_DEBUG in Windows-related C code. Patch by Xuehai Pan.

.. date: 2025-09-25-10-31-02 .. gh-issue: 139330 .. nonce: 5WWkY0 .. section: Tools/Demos

SBOM generation tool didn't cross-check the version and checksum values against the Modules/expat/refresh.sh script, leading to the values becoming out-of-date during routine updates.

.. date: 2025-08-28-06-22-26 .. gh-issue: 132006 .. nonce: eZQmc6 .. section: Tools/Demos

XCframeworks now include privacy manifests to satisfy Apple App Store submission requirements.

.. date: 2025-08-27-11-14-53 .. gh-issue: 138171 .. nonce: Suz8ob .. section: Tools/Demos

A script for building an iOS XCframework was added. As part of this change, the top level iOS folder has been moved to be a subdirectory of the Apple folder.

.. date: 2025-08-21-14-04-50 .. gh-issue: 137873 .. nonce: qxffLt .. section: Tools/Demos

The iOS test runner has been simplified, resolving some issues that have been observed using the runner in GitHub Actions and Azure Pipelines test environments.

.. date: 2025-08-06-11-54-55 .. gh-issue: 137484 .. nonce: 8iFAQs .. section: Tools/Demos

Have Tools/wasm/wasi put the build Python into a directory named after the build triple instead of "build".

.. date: 2025-08-01-13-27-43 .. gh-issue: 137025 .. nonce: ubuhQC .. section: Tools/Demos

The wasm_build.py script has been removed. Tools/wasm/emscripten and Tools/wasm/wasi should be used instead, as described in the Dev Guide <https://devguide.python.org/contrib/workflows/compile/>__.

.. date: 2025-07-30-11-15-47 .. gh-issue: 137248 .. nonce: 8IxwY3 .. section: Tools/Demos

Add a --logdir option to Tools/wasm/wasi for specifying where to write log files.

.. date: 2025-07-30-10-28-35 .. gh-issue: 137243 .. nonce: NkdUqH .. section: Tools/Demos

Have Tools/wasm/wasi detect a WASI SDK install in /opt when it was directly extracted from a release tarball.

.. date: 2025-07-05-15-10-42 .. gh-issue: 136251 .. nonce: GRM6o8 .. section: Tools/Demos

Fixes and usability improvements for Tools/wasm/emscripten/web_example

.. date: 2025-06-26-15-58-13 .. gh-issue: 135968 .. nonce: C4v_-W .. section: Tools/Demos

Stubs for strip are now provided as part of an iOS install.

.. date: 2025-06-11-12-14-06 .. gh-issue: 135379 .. nonce: 25ttXq .. section: Tools/Demos

The cases generator no longer accepts type annotations on stack items. Conversions to non-default types are now done explicitly in bytecodes.c and optimizer_bytecodes.c. This will simplify code generation for top-of-stack caching and other future features.

.. date: 2025-05-19-14-57-46 .. gh-issue: 134215 .. nonce: sbdDK6 .. section: Tools/Demos

:term:REPL import autocomplete only suggests private modules when explicitly specified.

.. date: 2025-09-22-15-40-09 .. gh-issue: 139208 .. nonce: Tc13dl .. section: Tests

Fix regrtest --fast-ci --verbose: don't ignore the --verbose option anymore. Patch by Victor Stinner.

.. date: 2025-09-21-16-00-30 .. gh-issue: 138313 .. nonce: lBx2en .. section: Tests

Restore skipped test and add janky workaround to prevent select buildbots from failing with a ResourceWarning.

.. date: 2025-06-26-15-15-35 .. gh-issue: 135966 .. nonce: EBpF8Y .. section: Tests

The iOS testbed now handles the app_packages folder as a site directory.

.. date: 2025-06-19-15-29-38 .. gh-issue: 135494 .. nonce: FVl9a0 .. section: Tests

Fix regrtest to support excluding tests from --pgo tests. Patch by Victor Stinner.

.. date: 2025-06-17-08-48-08 .. gh-issue: 132815 .. nonce: CY1Esu .. section: Tests

Fix test__opcode: add JUMP_BACKWARD to specialization stats.

.. date: 2025-06-14-13-20-17 .. gh-issue: 135489 .. nonce: Uh0yVO .. section: Tests

Show verbose output for failing tests during PGO profiling step with --enable-optimizations.

.. date: 2025-06-11-16-52-49 .. gh-issue: 135401 .. nonce: ccMXmL .. section: Tests

Add a new GitHub CI job to test the :mod:ssl module with AWS-LC <https://github.com/aws/aws-lc>_ as the backing cryptography and TLS library.

.. date: 2025-06-04-13-07-44 .. gh-issue: 135120 .. nonce: NapnZT .. section: Tests

Add :func:!test.support.subTests.

.. date: 2025-05-23-09-19-52 .. gh-issue: 134567 .. nonce: hwEIMb .. section: Tests

Expose log formatter to users in TestCase.assertLogs. :func:unittest.TestCase.assertLogs will now optionally accept a formatter that will be used to format the strings in output if provided.

.. date: 2025-05-09-14-54-48 .. gh-issue: 133744 .. nonce: LCquu0 .. section: Tests

Fix multiprocessing interrupt test. Add an event to synchronize the parent process with the child process: wait until the child process starts sleeping. Patch by Victor Stinner.

.. date: 2025-05-09-04-11-06 .. gh-issue: 133682 .. nonce: -_lwo3 .. section: Tests

Fixed test case test.test_annotationlib.TestStringFormat.test_displays which ensures proper handling of complex data structures (lists, sets, dictionaries, and tuples) in string annotations.

.. date: 2025-05-08-15-06-01 .. gh-issue: 133639 .. nonce: 50-kbV .. section: Tests

Fix TestPyReplAutoindent.test_auto_indent_default() doesn't run input_code.

.. date: 2025-10-07-19-31-34 .. gh-issue: 139700 .. nonce: vNHU1O .. section: Security

Check consistency of the zip64 end of central directory record. Support records with "zip64 extensible data" if there are no bytes prepended to the ZIP file.

.. date: 2025-09-29-00-01-28 .. gh-issue: 139400 .. nonce: X2T-jO .. section: Security

:mod:xml.parsers.expat: Make sure that parent Expat parsers are only garbage-collected once they are no longer referenced by subparsers created by :meth:~xml.parsers.expat.xmlparser.ExternalEntityParserCreate. Patch by Sebastian Pipping.

.. date: 2025-09-24-13-39-56 .. gh-issue: 139283 .. nonce: jODz_q .. section: Security

:mod:sqlite3: correctly handle maximum number of rows to fetch in :meth:Cursor.fetchmany <sqlite3.Cursor.fetchmany> and reject negative values for :attr:Cursor.arraysize <sqlite3.Cursor.arraysize>. Patch by Bénédikt Tran.

.. date: 2025-06-27-21-23-19 .. gh-issue: 136053 .. nonce: QZxcee .. section: Security

:mod:marshal: fix a possible crash when deserializing :class:slice objects.

.. date: 2025-06-25-14-13-39 .. gh-issue: 135661 .. nonce: idjQ0B .. section: Security

Fix parsing start and end tags in :class:html.parser.HTMLParser according to the HTML5 standard.

Whitespaces no longer accepted between </ and the tag name. E.g. </ script> does not end the script section.
Vertical tabulation (\v) and non-ASCII whitespaces no longer recognized as whitespaces. The only whitespaces are \t\n\r\f and space.
Null character (U+0000) no longer ends the tag name.
Attributes and slashes after the tag name in end tags are now ignored, instead of terminating after the first > in quoted attribute value. E.g. </script/foo=">"/>.
Multiple slashes and whitespaces between the last attribute and closing > are now ignored in both start and end tags. E.g. <a foo=bar/ //>.
Multiple = between attribute name and value are no longer collapsed. E.g. <a foo==bar> produces attribute "foo" with value "=bar".

.. date: 2025-06-18-13-34-55 .. gh-issue: 135661 .. nonce: NZlpWf .. section: Security

Fix CDATA section parsing in :class:html.parser.HTMLParser according to the HTML5 standard: ] ]> and ]] > no longer end the CDATA section. Add private method _set_support_cdata() which can be used to specify how to parse <[CDATA[ --- as a CDATA section in foreign content (SVG or MathML) or as a bogus comment in the HTML namespace.

.. date: 2025-06-18-13-28-08 .. gh-issue: 102555 .. nonce: nADrzJ .. section: Security

Fix comment parsing in :class:html.parser.HTMLParser according to the HTML5 standard. --!> now ends the comment. -- > no longer ends the comment. Support abnormally ended empty comments <--> and <--->.

.. date: 2025-06-13-15-55-22 .. gh-issue: 135462 .. nonce: KBeJpc .. section: Security

Fix quadratic complexity in processing specially crafted input in :class:html.parser.HTMLParser. End-of-file errors are now handled according to the HTML5 specs -- comments and declarations are automatically closed, tags are ignored.

.. date: 2025-06-09-20-38-25 .. gh-issue: 118350 .. nonce: KgWCcP .. section: Security

Fix support of escapable raw text mode (elements "textarea" and "title") in :class:html.parser.HTMLParser.

.. date: 2025-06-02-11-32-23 .. gh-issue: 135034 .. nonce: RLGjbp .. section: Security

Fixes multiple issues that allowed tarfile extraction filters (filter="data" and filter="tar") to be bypassed using crafted symlinks and hard links.

Addresses :cve:2024-12718, :cve:2025-4138, :cve:2025-4330, and :cve:2025-4517.

.. date: 2025-05-09-20-22-54 .. gh-issue: 133767 .. nonce: kN2i3Q .. section: Security

Fix use-after-free in the "unicode-escape" decoder with a non-"strict" error handler.

.. date: 2025-05-07-22-49-27 .. gh-issue: 133623 .. nonce: fgWkBm .. section: Security

Indicate through :data:ssl.HAS_PSK_TLS13 whether the :mod:ssl module supports "External PSKs" in TLSv1.3, as described in RFC 9258. Patch by Will Childs-Klein.

.. date: 2025-01-14-11-19-07 .. gh-issue: 128840 .. nonce: M1doZW .. section: Security

Short-circuit the processing of long IPv6 addresses early in :mod:ipaddress to prevent excessive memory consumption and a minor denial-of-service.

.. date: 2025-10-11-20-03-13 .. gh-issue: 139482 .. nonce: du2Stg .. section: Library

Optimize :data:os.environ.clear() <os.environ> by calling :manpage:clearenv(3) when this function is available. Patch by Victor Stinner.

.. date: 2025-10-11-17-41-26 .. gh-issue: 139958 .. nonce: AnCakj .. section: Library

The application/toml mime type is now supported by :mod:mimetypes. Patch by Gil Forcada.

.. date: 2025-10-11-14-37-42 .. gh-issue: 139823 .. nonce: uGF4oh .. section: Library

:mod:ensurepip now fails with a nicer error message when the :mod:zlib module is not available.

.. date: 2025-10-11-10-02-56 .. gh-issue: 139905 .. nonce: UyJIR_ .. section: Library

Add suggestion to error message for :class:typing.Generic subclasses when cls.__parameters__ is missing due to a parent class failing to call :meth:super().__init_subclass__() <object.__init_subclass__> in its __init_subclass__.

.. date: 2025-10-10-11-22-50 .. gh-issue: 139894 .. nonce: ECAXqj .. section: Library

Fix incorrect sharing of current task with the child process while forking in :mod:asyncio. Patch by Kumar Aditya.

.. date: 2025-10-09-21-37-20 .. gh-issue: 139845 .. nonce: dzx5UP .. section: Library

Fix to not print KeyboardInterrupt twice in default asyncio REPL.

.. date: 2025-10-09-13-48-28 .. gh-issue: 139783 .. nonce: __NUgo .. section: Library

Fix :func:inspect.getsourcelines for the case when a decorator is followed by a comment or an empty line.

.. date: 2025-10-09-03-06-19 .. gh-issue: 139809 .. nonce: lzHJNu .. section: Library

Prevent premature colorization of subparser prog in :meth:argparse.ArgumentParser.add_subparsers to respect color environment variable changes after parser creation.

.. date: 2025-10-08-00-06-30 .. gh-issue: 139736 .. nonce: baPeBd .. section: Library

Fix excessive indentation in the default :mod:argparse :class:!HelpFormatter. Patch by Alexander Edland.

.. date: 2025-10-02-17-40-10 .. gh-issue: 70765 .. nonce: zVlLZn .. section: Library

:mod:http.server: fix default handling of HTTP/0.9 requests in :class:~http.server.BaseHTTPRequestHandler. Previously, :meth:!BaseHTTPRequestHandler.parse_request incorrectly waited for headers in the request although those are not supported in HTTP/0.9. Patch by Bénédikt Tran.

.. date: 2025-10-02-15-45-08 .. gh-issue: 139322 .. nonce: rouPGj .. section: Library

Fix :func:os.getlogin error handling: fix the error number. Patch by Victor Stinner.

.. date: 2025-10-01-20-30-03 .. gh-issue: 135953 .. nonce: NAofJl .. section: Library

Add a Gecko format output to the tachyon profiler via --gecko.

.. date: 2025-09-29-14-15-20 .. gh-issue: 139184 .. nonce: dNl9O4 .. section: Library

:func:os.forkpty does now make the returned file descriptor non-inheritable.

.. date: 2025-09-28-16-34-11 .. gh-issue: 139391 .. nonce: nRFnmx .. section: Library

Fix an issue when, on non-Windows platforms, it was not possible to gracefully exit a python -m asyncio process suspended by Ctrl+Z and later resumed by :manpage:fg other than with :manpage:kill.

.. date: 2025-09-27-08-26-31 .. gh-issue: 139374 .. nonce: hfh-dl .. section: Library

:mod:timeit: Add color to error tracebacks.

.. date: 2025-09-26-18-04-28 .. gh-issue: 90949 .. nonce: YHjSzX .. section: Library

Add :meth:~xml.parsers.expat.xmlparser.SetBillionLaughsAttackProtectionActivationThreshold and :meth:~xml.parsers.expat.xmlparser.SetBillionLaughsAttackProtectionMaximumAmplification to :ref:xmlparser <xmlparser-objects> objects to tune protections against billion laughs <https://en.wikipedia.org/wiki/Billion_laughs_attack>_ attacks. Patch by Bénédikt Tran.

.. date: 2025-09-25-07-33-43 .. gh-issue: 139312 .. nonce: ygE8AC .. section: Library

Upgrade bundled libexpat to 2.7.3

.. date: 2025-09-24-14-17-34 .. gh-issue: 139289 .. nonce: Vmk25k .. section: Library

Do a real lazy-import on :mod:rlcompleter in :mod:pdb and restore the existing completer after importing :mod:rlcompleter.

.. date: 2025-09-22-14-40-11 .. gh-issue: 90949 .. nonce: UM35nb .. section: Library

Add :meth:~xml.parsers.expat.xmlparser.SetAllocTrackerActivationThreshold and :meth:~xml.parsers.expat.xmlparser.SetAllocTrackerMaximumAmplification to :ref:xmlparser <xmlparser-objects> objects to tune protections against disproportional amounts of dynamic memory usage from within an Expat parser. Patch by Bénédikt Tran.

.. date: 2025-09-22-11-30-45 .. gh-issue: 67795 .. nonce: fROoZt .. section: Library

Functions that take timestamp or timeout arguments now accept any real numbers (such as :class:~decimal.Decimal and :class:~fractions.Fraction), not only integers or floats, although this does not improve precision.

.. date: 2025-09-22-11-19-05 .. gh-issue: 95953 .. nonce: 7oLoag .. section: Library

A CSS class, diff_changed, was added to the changed lines in the make_table output of :class:difflib.HtmlDiff. Patch by Katie Gardner.

.. date: 2025-09-21-15-58-57 .. gh-issue: 139210 .. nonce: HGbMvz .. section: Library

Fix use-after-free when reporting unknown event in :func:xml.etree.ElementTree.iterparse. Patch by Ken Jin.

.. date: 2025-09-20-17-50-31 .. gh-issue: 138860 .. nonce: Y9JXap .. section: Library

Lazy import :mod:rlcompleter in :mod:pdb to avoid deadlock in subprocess.

.. date: 2025-09-19-09-36-42 .. gh-issue: 112729 .. nonce: mmty0_ .. section: Library

Fix crash when calling :func:concurrent.interpreters.create when the process is out of memory.

.. date: 2025-09-19-07-41-52 .. gh-issue: 126016 .. nonce: Uz9W6h .. section: Library

Fix an assertion failure when sending :exc:KeyboardInterrupt to a Python process running a subinterpreter in a separate thread.

.. date: 2025-09-18-14-21-57 .. gh-issue: 118803 .. nonce: 2JPbto .. section: Library

:class:collections.abc.ByteString has been removed from collections.abc.__all__, and :class:typing.ByteString has been removed from typing.__all__. The former has been deprecated since Python 3.12, and the latter has been deprecated since Python 3.9. Both classes are scheduled for removal in Python 3.17.

Additionally, the following statements now cause DeprecationWarning\ s to be emitted at runtime: from collections.abc import ByteString, from typing import ByteString, import collections.abc; collections.abc.ByteString and import typing; typing.ByteString. Both classes already caused DeprecationWarning\ s to be emitted if they were subclassed or used as the second argument to isinstance() or issubclass(), but they did not previously lead to DeprecationWarning\ s if they were merely imported or accessed from their respective modules.

.. date: 2025-09-18-05-32-18 .. gh-issue: 135729 .. nonce: 8AmMza .. section: Library

Fix unraisable exception during finalization when using :mod:concurrent.interpreters in the REPL.

.. date: 2025-09-17-21-54-53 .. gh-issue: 139076 .. nonce: 2eX9lG .. section: Library

Fix a bug in the :mod:pydoc module that was hiding functions in a Python module if they were implemented in an extension module and the module did not have __all__.

.. date: 2025-09-17-21-52-30 .. gh-issue: 139090 .. nonce: W7vbhF .. section: Library

Add :data:os.RWF_DONTCACHE constant for Linux 6.14+.

.. date: 2025-09-17-19-08-34 .. gh-issue: 139065 .. nonce: Hu8fM5 .. section: Library

Fix trailing space before a wrapped long word if the line length is exactly width in :mod:textwrap.

.. date: 2025-09-17-12-07-21 .. gh-issue: 139001 .. nonce: O6tseN .. section: Library

Fix race condition in :class:pathlib.Path on the internal _raw_paths field.

.. date: 2025-09-17-08-32-43 .. gh-issue: 138813 .. nonce: LHkHjX .. section: Library

:class:!multiprocessing.BaseProcess defaults kwargs to None instead of a shared dictionary.

.. date: 2025-09-16-19-05-29 .. gh-issue: 138998 .. nonce: URl0Y_ .. section: Library

Update bundled libexpat to 2.7.2

.. date: 2025-09-16-16-46-58 .. gh-issue: 138993 .. nonce: -8s8_T .. section: Library

Dedent :data:credits text.

.. date: 2025-09-16-15-56-29 .. gh-issue: 118803 .. nonce: aOPtmL .. section: Library

Add back :class:collections.abc.ByteString and :class:typing.ByteString. Both had been removed in prior alpha, beta and release candidates for Python 3.14, but their removal has now been postponed to Python 3.17.

.. date: 2025-09-15-19-29-12 .. gh-issue: 130567 .. nonce: shDEnT .. section: Library

Fix possible crash in :func:locale.strxfrm due to a platform bug on macOS.

.. date: 2025-09-15-13-09-19 .. gh-issue: 137226 .. nonce: HH3_ik .. section: Library

Fix :func:typing.get_type_hints calls on generic :class:typing.TypedDict classes defined with string annotations.

.. date: 2025-09-15-08-57-39 .. gh-issue: 138899 .. nonce: Uh6fvY .. section: Library

Executing quit command in :mod:pdb will raise :exc:bdb.BdbQuit when :mod:pdb is started from an asyncio console using :func:breakpoint or :func:pdb.set_trace.

.. date: 2025-09-12-01-01-05 .. gh-issue: 138804 .. nonce: 46ZukT .. section: Library

Raise :exc:TypeError instead of :exc:AttributeError when an argument of incorrect type is passed to :func:shlex.quote. This restores the behavior of the function prior to 3.14.

.. date: 2025-09-11-11-09-28 .. gh-issue: 138779 .. nonce: TNZnLr .. section: Library

Support device numbers larger than 2**63-1 for the :attr:~os.stat_result.st_rdev field of the :class:os.stat_result structure.

.. date: 2025-09-10-13-32-25 .. gh-issue: 138682 .. nonce: iExqx1 .. section: Library

Added symmetric difference support to :class:collections.Counter objects.

.. date: 2025-09-10-10-11-59 .. gh-issue: 138712 .. nonce: avrPG5 .. section: Library

Add :const:os.NODEV.

.. date: 2025-09-10-10-02-59 .. gh-issue: 128636 .. nonce: ldRKGZ .. section: Library

Fix crash in PyREPL when os.environ is overwritten with an invalid value for mac

.. date: 2025-09-09-17-57-49 .. gh-issue: 138720 .. nonce: hAtsm- .. section: Library

Fix an issue where :class:io.BufferedWriter and :class:io.BufferedRandom had different definitions of "closed" for :meth:~io.IOBase.close and :meth:~io.IOBase.flush which resulted in an exception when close called flush but flush thought the file was already closed.

.. date: 2025-09-09-10-48-26 .. gh-issue: 138706 .. nonce: xB--LX .. section: Library

Update :mod:unicodedata database to Unicode 17.0.0.

.. date: 2025-09-08-17-32-02 .. gh-issue: 76007 .. nonce: peEgcr .. section: Library

Deprecate __version__ from a number of standard library modules. Patch by Hugo van Kemenade.

.. date: 2025-09-06-20-09-32 .. gh-issue: 138535 .. nonce: mlntEe .. section: Library

Speed up :func:os.stat for files with reasonable timestamps. Contributed by Jeffrey Bosboom.

.. date: 2025-09-06-14-56-40 .. gh-issue: 116946 .. nonce: GGIeyO .. section: Library

:mod:curses.panel: the type of :func:curses.panel.new_panel is now immutable. Patch by Bénédikt Tran.

.. date: 2025-09-06-14-54-01 .. gh-issue: 116946 .. nonce: hzQEWI .. section: Library

:mod:zlib: the types of :func:zlib.compressobj and :func:zlib.decompressobj are now immutable. Patch by Bénédikt Tran.

.. date: 2025-09-06-14-53-19 .. gh-issue: 116946 .. nonce: c-npxd .. section: Library

:mod:os: the :class:os.DirEntry type and the type of :func:os.scandir are now immutable. Patch by Bénédikt Tran.

.. date: 2025-09-06-14-47-23 .. gh-issue: 116946 .. nonce: hj_u1t .. section: Library

:mod:tkinter: the types :class:!_tkinter.Tcl_Obj (wrapper for Tcl objects), :class:!_tkinter.tktimertoken (obtained by calling createtimerhandler() on a :attr:Tk <tkinter.Tk.tk> application) and :class:!_tkinter.tkapp (the runtime type of Tk applications) are now immutable. Patch by Bénédikt Tran.

.. date: 2025-09-06-11-26-21 .. gh-issue: 138514 .. nonce: 66ltOb .. section: Library

Raise :exc:ValueError when a multi-character string is passed to the echo_char parameter of :func:getpass.getpass. Patch by Benjamin Johnson.

.. date: 2025-09-05-21-10-24 .. gh-issue: 137706 .. nonce: 0EztiJ .. section: Library

Fix the partial evaluation of annotations that use typing.Annotated[T, x] where T is a forward reference.

.. date: 2025-09-05-15-35-59 .. gh-issue: 88375 .. nonce: dC491a .. section: Library

Fix normalization of the robots.txt rules and URLs in the :mod:urllib.robotparser module. No longer ignore trailing ?. Distinguish raw special characters ?, = and & from the percent-encoded ones.

.. date: 2025-09-05-07-50-18 .. gh-issue: 138515 .. nonce: E3M-pu .. section: Library

:mod:email is added to Emscripten build.

.. date: 2025-09-05-05-53-43 .. gh-issue: 99948 .. nonce: KMSlG6 .. section: Library

:func:ctypes.util.find_library now works in Emscripten build.

.. date: 2025-09-04-15-18-11 .. gh-issue: 111788 .. nonce: tuTEM5 .. section: Library

Fix parsing errors in the :mod:urllib.robotparser module. Don't fail trying to parse weird paths. Don't fail trying to decode non-UTF-8 robots.txt files.

.. date: 2025-09-03-15-20-10 .. gh-issue: 138432 .. nonce: RMc7UX .. section: Library

:meth:zoneinfo.reset_tzpath will now convert any :class:os.PathLike objects it receives into strings before adding them to TZPATH. It will raise TypeError if anything other than a string is found after this conversion. If given an :class:os.PathLike object that represents a relative path, it will now raise ValueError instead of TypeError, and present a more informative error message.

.. date: 2025-09-03-09-03-11 .. gh-issue: 132657 .. nonce: cbAIDh .. section: Library

Improve the scaling of :func:copy.copy and :func:copy.deepcopy in the free-threading build.

.. date: 2025-09-02-10-27-21 .. gh-issue: 116946 .. nonce: VxXNGD .. section: Library

The types of :func:select.poll and :func:select.epoll objects are now immutable. Patch by Bénédikt Tran.

.. date: 2025-09-02-10-23-09 .. gh-issue: 116946 .. nonce: U6RpwK .. section: Library

The :class:!_random.Random C type is now immutable. Patch by Bénédikt Tran.

.. date: 2025-08-31-22-10-22 .. gh-issue: 57911 .. nonce: N_Ixtv .. section: Library

When extracting tar files on Windows, slashes in symlink targets will be replaced by backslashes to prevent corrupted links.

.. date: 2025-08-31-12-34-02 .. gh-issue: 138205 .. nonce: iHXb1z .. section: Library

Removed the :meth:~mmap.mmap.resize method on platforms that don't support the underlying syscall, instead of raising a :exc:SystemError.

.. date: 2025-08-31-09-06-49 .. gh-issue: 138008 .. nonce: heOvsU .. section: Library

Fix segmentation faults in the :mod:ctypes module due to invalid :attr:~ctypes._CFuncPtr.argtypes. Patch by Dung Nguyen.

.. date: 2025-08-30-17-58-04 .. gh-issue: 138252 .. nonce: CDiEby .. section: Library

:mod:ssl: :class:~ssl.SSLContext objects can now set client and server TLS signature algorithms. If Python has been built with OpenSSL 3.5 or later, :class:~ssl.SSLSocket objects can return the signature algorithms selected on a connection.

.. date: 2025-08-30-10-58-15 .. gh-issue: 138253 .. nonce: 9Ehj-N .. section: Library

Add the block parameter in the :meth:!put and :meth:!get methods of the :mod:concurrent.interpreters queues for compatibility with the :class:queue.Queue interface.

.. date: 2025-08-30-10-04-28 .. gh-issue: 60462 .. nonce: yh_vDc .. section: Library

Fix :func:locale.strxfrm on Solaris (and possibly other platforms).

.. date: 2025-08-29-12-56-55 .. gh-issue: 138239 .. nonce: uthZFI .. section: Library

The REPL now highlights :keyword:type as a soft keyword in :ref:type statements <type>.

.. date: 2025-08-29-12-05-33 .. gh-issue: 78502 .. nonce: VpIMxg .. section: Library

:class:mmap.mmap now has a trackfd parameter on Windows; if it is False, the file handle corresponding to fileno will not be duplicated.

.. date: 2025-08-28-13-20-09 .. gh-issue: 138204 .. nonce: 8oLOud .. section: Library

Forbid expansion of shared anonymous :mod:memory maps <mmap> on Linux, which caused a bus error.

.. date: 2025-08-27-17-05-36 .. gh-issue: 138010 .. nonce: ZZJmPL .. section: Library

Fix an issue where defining a class with a :deco:warnings.deprecated-decorated base class may not invoke the correct :meth:~object.__init_subclass__ method in cases involving multiple inheritance. Patch by Brian Schubert.

.. date: 2025-08-25-22-38-03 .. gh-issue: 134716 .. nonce: kyYKeX .. section: Library

Add support of regular expressions in the :option:-W option and the :envvar:PYTHONWARNINGS environment variable.

.. date: 2025-08-25-18-06-04 .. gh-issue: 138133 .. nonce: Zh9rGo .. section: Library

Prevent infinite traceback loop when sending CTRL^C to Python through strace.

.. date: 2025-08-25-16-22-32 .. gh-issue: 138122 .. nonce: eMNDZ1 .. section: Library

Implement :pep:799 -- A dedicated profiling package for organizing Python profiling tools. Patch by Pablo Galindo.

.. date: 2025-08-24-02-04-32 .. gh-issue: 138092 .. nonce: V4-wTO .. section: Library

Fixed a bug in :meth:mmap.mmap.flush where calling with only an offset parameter would fail.

.. date: 2025-08-22-12-48-14 .. gh-issue: 138044 .. nonce: lEQULC .. section: Library

Remove compatibility shim for deprecated parameter package in :func:importlib.resources.files. Patch by Semyon Moroz.

.. date: 2025-08-22-09-53-45 .. gh-issue: 86819 .. nonce: ECxvwx .. section: Library

:mod:socket: Add missing constants for ISO-TP sockets.

.. date: 2025-08-19-00-12-57 .. gh-issue: 137884 .. nonce: 4faCA_ .. section: Library

Add :func:threading.get_native_id support for Illumos/Solaris. Patch by Yüce Tekol.

.. date: 2025-08-18-16-02-51 .. gh-issue: 134869 .. nonce: GnAjnU .. section: Library

Fix an issue where pressing Ctrl+C during tab completion in the REPL would leave the autocompletion menu in a corrupted state.

.. date: 2025-08-18-07-10-55 .. gh-issue: 137840 .. nonce: 9b7AnG .. section: Library

:class:typing.TypedDict now supports the closed and extra_items keyword arguments (as described in :pep:728) to control whether additional non-required keys are allowed and to specify their value type.

.. date: 2025-08-17-10-22-31 .. gh-issue: 132947 .. nonce: XR4MJ8 .. section: Library

Applied changes to importlib.metadata from importlib_metadata 8.7 <https://importlib-metadata.readthedocs.io/en/latest/history.html#v8-7-0>_, including dist now disallowed for EntryPoints.select; deferred imports for faster import times; added support for metadata with newlines (python/cpython#119650); and metadata() function now returns None when a metadata directory is present but no metadata is present.

.. date: 2025-08-16-18-11-41 .. gh-issue: 90548 .. nonce: q3aJUK .. section: Library

Fix musl detection for :func:platform.libc_ver on Alpine Linux if compiled with --strip-all.

.. date: 2025-08-16-16-04-15 .. gh-issue: 137317 .. nonce: Dl13B5 .. section: Library

:func:inspect.signature now correctly handles classes that use a descriptor on a wrapped :meth:!__init__ or :meth:!__new__ method. Contributed by Yongyu Yan.

.. date: 2025-08-16-09-02-11 .. gh-issue: 137754 .. nonce: mCev1Y .. section: Library

Fix import of the :mod:zoneinfo module if the C implementation of the :mod:datetime module is not available.

.. date: 2025-08-14-10-27-07 .. gh-issue: 125854 .. nonce: vDzFcZ .. section: Library

Improve error messages for invalid category in :func:warnings.warn.

.. date: 2025-08-14-00-00-12 .. gh-issue: 137729 .. nonce: i9NSKP .. section: Library

:func:locale.setlocale now supports language codes with @-modifiers. @-modifier are no longer silently removed in :func:locale.getlocale, but included in the language code.

.. date: 2025-08-13-10-50-22 .. gh-issue: 73487 .. nonce: DUHbBq .. section: Library

Speedup processing arguments (up to 1.5x) in the :mod:decimal module methods, that now using :c:macro:METH_FASTCALL calling convention. Patch by Sergey B Kirpichev.

.. date: 2025-08-11-14-18-32 .. gh-issue: 137634 .. nonce: M7iBG6 .. section: Library

Calendar pages generated by the :class:calendar.HTMLCalendar class now support dark mode and have been migrated to the HTML5 standard for improved accessibility.

.. date: 2025-08-11-05-05-08 .. gh-issue: 137630 .. nonce: 9lmqyc .. section: Library

The :mod:!_interpreters module now uses Argument Clinic to parse arguments. Patch by Adam Turner.

.. date: 2025-08-09-08-53-32 .. gh-issue: 137583 .. nonce: s6OZud .. section: Library

Fix a deadlock introduced in 3.13.6 when a call to :meth:ssl.SSLSocket.recv <socket.socket.recv> was blocked in one thread, and then another method on the object (such as :meth:ssl.SSLSocket.send <socket.socket.send>) was subsequently called in another thread.

.. date: 2025-08-08-21-20-14 .. gh-issue: 92936 .. nonce: rOgG1S .. section: Library

Update regex used by http.cookies.SimpleCookie to handle values containing double quotes.

.. date: 2025-08-08-15-00-38 .. gh-issue: 137426 .. nonce: lW-Rk2 .. section: Library

Remove the code deprecation of importlib.abc.ResourceLoader. It is documented as deprecated, but left for backwards compatibility with other classes in importlib.abc.

.. date: 2025-08-07-17-18-57 .. gh-issue: 137490 .. nonce: s89ieZ .. section: Library

Handle :data:~errno.ECANCELED in the same way as :data:~errno.EINTR in :func:signal.sigwaitinfo on NetBSD.

.. date: 2025-08-07-15-07-44 .. gh-issue: 137512 .. nonce: j2or5h .. section: Library

Add new constants in the :mod:resource module: :data:~resource.RLIMIT_NTHR, :data:~resource.RLIMIT_UMTXP, :data:~resource.RLIMIT_PIPEBUF, :data:~resource.RLIMIT_THREADS, :data:~resource.RLIM_SAVED_CUR, and :data:~resource.RLIM_SAVED_MAX.

.. date: 2025-08-07-12-32-23 .. gh-issue: 137044 .. nonce: abNoIy .. section: Library

:data:resource.RLIM_INFINITY is now always a positive integer. On all supported platforms, it is larger than any limited resource value, which simplifies comparison of the resource values. Previously, it could be negative, such as -1 or -3, depending on platform.

.. date: 2025-08-06-23-16-42 .. gh-issue: 137477 .. nonce: bk6BDV .. section: Library

Fix :func:!inspect.getblock, :func:inspect.getsourcelines and :func:inspect.getsource for generator expressions.

.. date: 2025-08-06-16-54-22 .. gh-issue: 137481 .. nonce: eSTkK0 .. section: Library

Calendar uses the lengths of the locale's weekdays to decide if the width requires abbreviation.

.. date: 2025-08-06-16-13-47 .. gh-issue: 137466 .. nonce: Whv0-A .. section: Library

Remove undocumented :func:!glob.glob0 and :func:!glob.glob1 functions, which have been deprecated since Python 3.13. Use :func:glob.glob and pass a directory to its root_dir argument instead.

.. date: 2025-08-03-13-16-39 .. gh-issue: 137044 .. nonce: 0hPVL_ .. section: Library

Return large limit values as positive integers instead of negative integers in :func:resource.getrlimit. Accept large values and reject negative values (except :data:~resource.RLIM_INFINITY) for limits in :func:resource.setrlimit.

.. date: 2025-08-03-00-36-57 .. gh-issue: 115766 .. nonce: nJCFkW .. section: Library

Fix :attr:!ipaddress.IPv4Interface.is_unspecified.

.. date: 2025-08-01-23-52-49 .. gh-issue: 75989 .. nonce: 5aYXNJ .. section: Library

:func:tarfile.TarFile.extractall and :func:tarfile.TarFile.extract now overwrite symlinks when extracting hardlinks. (Contributed by Alexander Enrique Urieles Nieto in :gh:75989.)

.. date: 2025-08-01-23-11-25 .. gh-issue: 137017 .. nonce: 0yGcNc .. section: Library

Fix :obj:threading.Thread.is_alive to remain True until the underlying OS thread is fully cleaned up. This avoids false negatives in edge cases involving thread monitoring or premature :obj:threading.Thread.is_alive calls.

.. date: 2025-08-01-15-07-59 .. gh-issue: 137273 .. nonce: 4V8Xmv .. section: Library

Fix debug assertion failure in :func:locale.setlocale on Windows.

.. date: 2025-07-31-16-43-16 .. gh-issue: 137191 .. nonce: FIogE8 .. section: Library

Fix how type parameters are collected, when :class:typing.Protocol are specified with explicit parameters. Now, :class:typing.Generic and :class:typing.Protocol always dictate the parameter number and parameter ordering of types. Previous behavior was a bug.

.. date: 2025-07-31-10-31-56 .. gh-issue: 137282 .. nonce: GOCwIC .. section: Library

Fix tab completion and :func:dir on :mod:concurrent.futures.

.. date: 2025-07-30-18-07-33 .. gh-issue: 137257 .. nonce: XBtzf2 .. section: Library

Bump the version of pip bundled in ensurepip to version 25.2

.. date: 2025-07-30-17-42-36 .. gh-issue: 137239 .. nonce: qSpj32 .. section: Library

:mod:heapq: Update :data:!heapq.__all__ with *_max functions.

.. date: 2025-07-30-11-12-22 .. gh-issue: 124503 .. nonce: d4hc7b .. section: Library

:func:ast.literal_eval is 10-20% faster for small inputs.

.. date: 2025-07-29-21-18-31 .. gh-issue: 137226 .. nonce: B_4lpu .. section: Library

Fix behavior of :meth:annotationlib.ForwardRef.evaluate when the type_params parameter is passed and the name of a type param is also present in an enclosing scope.

.. date: 2025-07-29-05-12-50 .. gh-issue: 137197 .. nonce: bMK3sO .. section: Library

:class:~ssl.SSLContext objects can now set TLS 1.3 cipher suites via :meth:~ssl.SSLContext.set_ciphersuites.

.. date: 2025-07-28-23-11-29 .. gh-issue: 81325 .. nonce: jMJFBe .. section: Library

:class:tarfile.TarFile now accepts a :term:path-like <path-like object> when working on a tar archive. (Contributed by Alexander Enrique Urieles Nieto in :gh:81325.)

.. date: 2025-07-28-20-48-32 .. gh-issue: 137185 .. nonce: fgI7-B .. section: Library

Fix a potential async-signal-safety issue in :mod:faulthandler when printing C stack traces.

.. date: 2025-07-27-17-03-17 .. gh-issue: 133951 .. nonce: 7kwt78 .. section: Library

Remove lib64-lib symlink creation when creating new virtual environments in :mod:venv module

.. date: 2025-07-25-09-21-56 .. gh-issue: 130522 .. nonce: Crwq68 .. section: Library

Fix unraisable :exc:TypeError raised during :term:interpreter shutdown in the :mod:threading module.

.. date: 2025-07-24-00-38-07 .. gh-issue: 137059 .. nonce: fr64oW .. section: Library

Fix handling of file URLs with a Windows drive letter in the URL authority by :func:urllib.request.url2pathname. This fixes a regression in earlier pre-releases of Python 3.14.

.. date: 2025-07-23-11-59-48 .. gh-issue: 136980 .. nonce: BIJzkB .. section: Library

Remove unused C tracing code in bdb for event type c_call, c_return and c_exception

.. date: 2025-07-23-00-35-29 .. gh-issue: 130577 .. nonce: c7EITy .. section: Library

:mod:tarfile now validates archives to ensure member offsets are non-negative. (Contributed by Alexander Enrique Urieles Nieto in :gh:130577.)

.. date: 2025-07-21-22-35-50 .. gh-issue: 136170 .. nonce: QUlc78 .. section: Library

Removed the unreleased zipfile.ZipFile.data_offset property added in 3.14.0a7 as it wasn't fully clear which behavior it should have in some situations so the result was not always what a user might expect.

.. date: 2025-07-21-20-00-42 .. gh-issue: 121237 .. nonce: DyxNqo .. section: Library

Support %:z directive for :meth:datetime.datetime.strptime, :meth:datetime.time.strptime and :func:time.strptime. Patch by Lucas Esposito and Semyon Moroz.

.. date: 2025-07-21-16-13-20 .. gh-issue: 136929 .. nonce: obKZ2S .. section: Library

Ensure that hash functions guaranteed to be always available exist as attributes of :mod:hashlib even if they will not work at runtime due to missing backend implementations. For instance, hashlib.md5 will no longer raise :exc:AttributeError if OpenSSL is not available and Python has been built without MD5 support. Patch by Bénédikt Tran.

.. date: 2025-07-21-16-10-24 .. gh-issue: 124621 .. nonce: wyoWc1 .. section: Library

pyrepl now works in Emscripten.

.. date: 2025-07-21-15-40-00 .. gh-issue: 136914 .. nonce: -GNG-d .. section: Library

Fix retrieval of :attr:doctest.DocTest.lineno for objects decorated with :func:functools.cache or :class:functools.cached_property.

.. date: 2025-07-21-11-56-47 .. gh-issue: 136912 .. nonce: zWosAL .. section: Library

:func:hmac.digest now properly handles large keys and messages by falling back to the pure Python implementation when necessary. Patch by Bénédikt Tran.

.. date: 2025-07-21-01-16-32 .. gh-issue: 83424 .. nonce: Y3tEV4 .. section: Library

Allows creating a :class:ctypes.CDLL without name when passing a handle as an argument.

.. date: 2025-07-20-16-56-55 .. gh-issue: 135228 .. nonce: n_XIao .. section: Library

When :mod:dataclasses replaces a class with a slotted dataclass, the original class can now be garbage collected again. Earlier changes in Python 3.14 caused this class to always remain in existence together with the replacement class synthesized by :mod:dataclasses.

.. date: 2025-07-20-16-02-00 .. gh-issue: 136874 .. nonce: cLC3o1 .. section: Library

Discard URL query and fragment in :func:urllib.request.url2pathname.

.. date: 2025-07-20-10-21-49 .. gh-issue: 136787 .. nonce: 0Rbp .. section: Library

:mod:hashlib: improve exception messages when a hash algorithm is not recognized, blocked by the current security policy or incompatible with the desired operation (for instance, using HMAC with SHAKE). Patch by Bénédikt Tran.

.. date: 2025-07-19-16-20-54 .. gh-issue: 130645 .. nonce: O-dYcN .. section: Library

Enable color help by default in :mod:argparse.

.. date: 2025-07-19-15-40-47 .. gh-issue: 131724 .. nonce: LS59nA .. section: Library

In :mod:http.client, a new max_response_headers keyword-only parameter has been added to :class:~http.client.HTTPConnection and :class:~http.client.HTTPSConnection constructors. This parameter sets the maximum number of allowed response headers, helping to prevent denial-of-service attacks.

.. date: 2025-07-19-11-53-19 .. gh-issue: 135427 .. nonce: iJM_X2 .. section: Library

With :option:-Werror <-W>, the DeprecationWarning emitted by :py:func:os.fork and :py:func:os.forkpty in mutli-threaded processes is now raised as an exception. Previously it was silently ignored. Patch by Rani Pinchuk.

.. date: 2025-07-17-16-12-23 .. gh-issue: 136234 .. nonce: VmTxtj .. section: Library

Fix :meth:asyncio.WriteTransport.writelines to be robust to connection failure, by using the same behavior as :meth:~asyncio.WriteTransport.write.

.. date: 2025-07-16-09-45-58 .. gh-issue: 53144 .. nonce: mrKwMW .. section: Library

:mod:!encodings.aliases: Add latin_N aliases

.. date: 2025-07-15-16-37-34 .. gh-issue: 136669 .. nonce: Yexwah .. section: Library

:mod:!_asyncio is now statically linked for improved performance.

.. date: 2025-07-13-13-31-22 .. gh-issue: 136134 .. nonce: mh6VjS .. section: Library

:meth:!SMTP.auth_cram_md5 now raises an :exc:~smtplib.SMTPException instead of a :exc:ValueError if Python has been built without MD5 support. In particular, :class:~smtplib.SMTP clients will not attempt to use this method even if the remote server is assumed to support it. Patch by Bénédikt Tran.

.. date: 2025-07-13-11-20-05 .. gh-issue: 136134 .. nonce: xhh0Kq .. section: Library

:meth:IMAP4.login_cram_md5 <imaplib.IMAP4.login_cram_md5> now raises an :exc:IMAP4.error <imaplib.IMAP4.error> if CRAM-MD5 authentication is not supported. Patch by Bénédikt Tran.

.. date: 2025-07-12-18-05-37 .. gh-issue: 136591 .. nonce: ujXmSN .. section: Library

:mod:!_hashlib: avoid using deprecated functions :manpage:ERR_func_error_string and :manpage:EVP_MD_CTX_md when using OpenSSL 3.0 and later. Patch by Bénédikt Tran.

.. date: 2025-07-12-14-15-47 .. gh-issue: 136571 .. nonce: muHmBv .. section: Library

:meth:datetime.date.fromisocalendar can now raise OverflowError for out of range arguments.

.. date: 2025-07-11-23-04-39 .. gh-issue: 136549 .. nonce: oAi8u4 .. section: Library

Fix signature of :func:threading.excepthook.

.. date: 2025-07-11-10-23-44 .. gh-issue: 136492 .. nonce: BVi5h0 .. section: Library

Expose :pep:667's :data:~types.FrameLocalsProxyType in the :mod:types module.

.. date: 2025-07-11-08-15-17 .. gh-issue: 83336 .. nonce: ptpmq7 .. section: Library

utf8_sig is now aliased to :mod:encodings.utf_8_sig

.. date: 2025-07-11-03-39-15 .. gh-issue: 136523 .. nonce: s7caKL .. section: Library

Fix :class:wave.Wave_write emitting an unraisable when open raises.

.. date: 2025-07-10-21-02-43 .. gh-issue: 136507 .. nonce: pnEuGS .. section: Library

Fix mimetypes CLI to handle multiple file parameters.

.. date: 2025-07-10-10-18-19 .. gh-issue: 52876 .. nonce: 9Vjrd8 .. section: Library

Add missing keepends (default True) parameter to :meth:!codecs.StreamReaderWriter.readline and :meth:!codecs.StreamReaderWriter.readlines.

.. date: 2025-07-10-00-47-37 .. gh-issue: 136470 .. nonce: KlUEUG .. section: Library

Correct :class:concurrent.futures.InterpreterPoolExecutor's default thread name.

.. date: 2025-07-09-20-29-30 .. gh-issue: 136476 .. nonce: HyLLzh .. section: Library

Fix a bug that was causing the get_async_stack_trace function to miss some frames in the stack trace.

.. date: 2025-07-08-20-58-01 .. gh-issue: 136434 .. nonce: uuJsjS .. section: Library

Fix docs generation of UnboundItem in :mod:concurrent.interpreters when running with :option:-OO.

.. date: 2025-07-07-22-12-32 .. gh-issue: 136380 .. nonce: 1b_nXl .. section: Library

Raises :exc:AttributeError when accessing :class:concurrent.futures.InterpreterPoolExecutor and subinterpreters are not available.

.. date: 2025-07-07-16-46-55 .. gh-issue: 72327 .. nonce: wLvRuj .. section: Library

Suggest using the system command prompt when pip install is typed into the REPL. Patch by Tom Viner, Richard Si, and Brian Schubert.

.. date: 2025-07-06-18-38-10 .. gh-issue: 135953 .. nonce: Z29DCz .. section: Library

Implement a new high-frequency runtime profiler that leverages the existing remote debugging functionality to collect detailed execution statistics from running Python processes. This tool is exposed in the profile.sample module and enables non-intrusive observation of production applications by attaching to already-running processes without requiring any code modifications, restarts, or special startup flags. The observer can perform extremely high-frequency sampling of stack traces and interpreter state, providing detailed runtime execution analysis of live applications.

.. date: 2025-07-06-10-18-48 .. gh-issue: 136021 .. nonce: f-FJYT .. section: Library

Make type_params parameter required in :func:!typing._eval_type after a deprecation period for not providing this parameter. Also remove the :exc:DeprecationWarning for the old behavior.

.. date: 2025-07-05-09-45-04 .. gh-issue: 136286 .. nonce: N67Amr .. section: Library

Fix pickling failures for protocols 0 and 1 for many objects related to subinterpreters.

.. date: 2025-07-05-06-59-46 .. gh-issue: 136047 .. nonce: qWvycf .. section: Library

Fix issues with :mod:typing when the C implementation of :mod:abc is not available.

.. date: 2025-07-05-06-56-16 .. gh-issue: 136316 .. nonce: 3zj_Do .. section: Library

Improve support for evaluating nested forward references in :func:typing.evaluate_forward_ref.

.. date: 2025-07-04-23-45-00 .. gh-issue: 136306 .. nonce: O1YLIU .. section: Library

:mod:ssl can now get and set groups used for key agreement.

.. date: 2025-07-04-12-53-02 .. gh-issue: 136156 .. nonce: OYlXoz .. section: Library

:func:tempfile.TemporaryFile no longer uses :data:os.O_EXCL with :data:os.O_TMPFILE, so it's possible to use linkat() on the file descriptor. Patch by Victor Stinner.

.. date: 2025-07-02-18-41-45 .. gh-issue: 133982 .. nonce: 7qqAn6 .. section: Library

Update Python implementation of :class:io.BytesIO to be thread safe.

.. date: 2025-07-02-10-48-21 .. gh-issue: 136193 .. nonce: xfvras .. section: Library

Improve :exc:TypeError error message, when richcomparing two :class:types.SimpleNamespace objects.

.. date: 2025-07-01-14-44-03 .. gh-issue: 136097 .. nonce: bI1n14 .. section: Library

Fix potential infinite recursion and KeyError in sysconfig --generate-posix-vars.

.. date: 2025-06-30-11-12-24 .. gh-issue: 85702 .. nonce: 0Lrbwu .. section: Library

If zoneinfo._common.load_tzdata is given a package without a resource a :exc:zoneinfo.ZoneInfoNotFoundError is raised rather than a :exc:PermissionError. Patch by Victor Stinner.

.. date: 2025-06-29-15-22-13 .. gh-issue: 90733 .. nonce: NiquaA .. section: Library

Improve error messages when reporting invalid parameters in :func:hashlib.scrypt. Patch by Bénédikt Tran.

.. date: 2025-06-28-11-32-57 .. gh-issue: 134759 .. nonce: AjjKcG .. section: Library

Fix :exc:UnboundLocalError in :func:email.message.Message.get_payload when the payload to decode is a :class:bytes object. Patch by Kliment Lamonov.

.. date: 2025-06-27-13-34-28 .. gh-issue: 136028 .. nonce: RY727g .. section: Library

Fix parsing month names containing "İ" (U+0130, LATIN CAPITAL LETTER I WITH DOT ABOVE) in :func:time.strptime. This affects locales az_AZ, ber_DZ, ber_MA and crh_UA.

.. date: 2025-06-27-09-26-04 .. gh-issue: 87135 .. nonce: 33z0UW .. section: Library

Acquiring a :class:threading.Lock or :class:threading.RLock at interpreter shutdown will raise :exc:PythonFinalizationError if Python can determine that it would otherwise deadlock.

.. date: 2025-06-26-17-28-49 .. gh-issue: 135995 .. nonce: pPrDCt .. section: Library

In the palmos encoding, make byte 0x9b decode to › (U+203A - SINGLE RIGHT-POINTING ANGLE QUOTATION MARK).

.. date: 2025-06-26-17-19-36 .. gh-issue: 105456 .. nonce: eR9oHB .. section: Library

Removed :mod:!sre_compile, :mod:!sre_constants and :mod:!sre_parse modules.

.. date: 2025-06-26-11-52-40 .. gh-issue: 53203 .. nonce: TMigBr .. section: Library

Fix :func:time.strptime for %c and %x formats on locales byn_ER, wal_ET and lzh_TW, and for %X format on locales ar_SA, bg_BG and lzh_TW.

.. date: 2025-06-24-14-43-24 .. gh-issue: 135878 .. nonce: Db4roX .. section: Library

Fixes a crash of :class:types.SimpleNamespace on :term:free threading builds, when several threads were calling its :meth:~object.__repr__ method at the same time.

.. date: 2025-06-24-13-30-47 .. gh-issue: 135853 .. nonce: 7ejTvK .. section: Library

Add :func:math.fmax and :func:math.fmin to get the larger and smaller of two floating-point values. Patch by Bénédikt Tran.

.. date: 2025-06-24-10-52-35 .. gh-issue: 135836 .. nonce: s37351 .. section: Library

Fix :exc:IndexError in :meth:asyncio.loop.create_connection that could occur when non-\ :exc:OSError exception is raised during connection and socket's close() raises :exc:!OSError.

.. date: 2025-06-24-10-23-37 .. gh-issue: 135853 .. nonce: 6xDNOG .. section: Library

:mod:math: expose C99 :func:~math.signbit function to determine whether the sign bit of a floating-point value is set. Patch by Bénédikt Tran.

.. date: 2025-06-23-13-02-08 .. gh-issue: 134531 .. nonce: yUmj07 .. section: Library

:mod:hmac: use the :manpage:EVP_MAC(3ssl) interface for HMAC when Python is built with OpenSSL 3.0 and later instead of the deprecated :manpage:HMAC_CTX(3ssl) <hmac(3)> interface. Patch by Bénédikt Tran.

.. date: 2025-06-23-11-04-25 .. gh-issue: 135836 .. nonce: -C-c4v .. section: Library

Fix :exc:IndexError in :meth:asyncio.loop.create_connection that could occur when the Happy Eyeballs algorithm resulted in an empty exceptions list during connection attempts.

.. date: 2025-06-23-10-19-11 .. gh-issue: 135855 .. nonce: -J0AGF .. section: Library

Raise :exc:TypeError instead of :exc:SystemError when :func:!_interpreters.set___main___attrs is passed a non-dict object. Patch by Brian Schubert.

.. date: 2025-06-22-22-03-06 .. gh-issue: 135823 .. nonce: iDBg97 .. section: Library

:mod:netrc: improve the error message when the security check for the ownership of the default configuration file ~/.netrc fails. Patch by Bénédikt Tran.

.. date: 2025-06-22-16-23-44 .. gh-issue: 135815 .. nonce: 0DandH .. section: Library

:mod:netrc: skip security checks if :func:os.getuid is missing. Patch by Bénédikt Tran.

.. date: 2025-06-22-02-16-17 .. gh-issue: 135640 .. nonce: FXyFL6 .. section: Library

Address bug where it was possible to call :func:xml.etree.ElementTree.ElementTree.write on an ElementTree object with an invalid root element. This behavior blanked the file passed to write if it already existed.

.. date: 2025-06-20-17-06-59 .. gh-issue: 90117 .. nonce: GYWVrn .. section: Library

Speed up :mod:pprint for :class:list and :class:tuple.

.. date: 2025-06-20-16-28-47 .. gh-issue: 135759 .. nonce: jne0Zi .. section: Library

:mod:hashlib: reject negative digest lengths in OpenSSL-based SHAKE objects by raising a :exc:ValueError. Previously, negative lengths were implicitly rejected by raising a :exc:MemoryError or a :exc:SystemError. Patch by Bénédikt Tran.

.. date: 2025-06-18-19-25-32 .. gh-issue: 123471 .. nonce: lx1Xbt .. section: Library

Make concurrent iterations over :class:itertools.chain safe under :term:free threading.

.. date: 2025-06-18-13-58-13 .. gh-issue: 135645 .. nonce: 109nff .. section: Library

Added supports_isolated_interpreters field to :data:sys.implementation.

.. date: 2025-06-18-11-43-17 .. gh-issue: 135646 .. nonce: r7ekEn .. section: Library

Raise consistent :exc:NameError exceptions in :func:annotationlib.ForwardRef.evaluate

.. date: 2025-06-17-23-13-56 .. gh-issue: 135557 .. nonce: Bfcy4v .. section: Library

Fix races on :mod:heapq updates and :class:list reads on the :term:free threaded <free threading> build.

.. date: 2025-06-17-22-44-19 .. gh-issue: 119180 .. nonce: Ogv8Nj .. section: Library

Only fetch globals and locals if necessary in :func:annotationlib.get_annotations

.. date: 2025-06-16-15-03-03 .. gh-issue: 135561 .. nonce: mJCN8D .. section: Library

Fix a crash on DEBUG builds when an HACL* HMAC routine fails. Patch by Bénédikt Tran.

.. date: 2025-06-16-15-00-13 .. gh-issue: 135386 .. nonce: lNrxLc .. section: Library

Fix opening a :mod:dbm.sqlite3 database for reading from read-only file or directory.

.. date: 2025-06-16-12-37-02 .. gh-issue: 135444 .. nonce: An2eeA .. section: Library

Fix :meth:asyncio.DatagramTransport.sendto to account for datagram header size when data cannot be sent.

.. date: 2025-06-15-03-03-22 .. gh-issue: 65697 .. nonce: COdwZd .. section: Library

:class:configparser's error message when attempting to write an invalid key is now more helpful.

.. date: 2025-06-14-14-19-13 .. gh-issue: 135497 .. nonce: 1pzwdA .. section: Library

Fix :func:os.getlogin failing for longer usernames on BSD-based platforms.

.. date: 2025-06-14-12-06-55 .. gh-issue: 135487 .. nonce: KdVFff .. section: Library

Fix :meth:!reprlib.Repr.repr_int when given integers with more than :func:sys.get_int_max_str_digits digits. Patch by Bénédikt Tran.

.. date: 2025-06-12-18-15-31 .. gh-issue: 135429 .. nonce: mch75_ .. section: Library

Fix the argument mismatch in _lsprof for PY_THROW event.

.. date: 2025-06-12-10-45-02 .. gh-issue: 135368 .. nonce: OjWVHL .. section: Library

Fix :class:unittest.mock.Mock generation on :func:dataclasses.dataclass objects. Now all special attributes are set as it was before :gh:124429.

.. date: 2025-06-11-15-08-02 .. gh-issue: 135336 .. nonce: 6Gq6MI .. section: Library

:mod:json now encodes strings up to 2.2x faster if they consist solely of characters that don’t require escaping.

.. date: 2025-06-10-21-42-04 .. gh-issue: 135335 .. nonce: WnUqb_ .. section: Library

:mod:multiprocessing: Flush stdout and stderr after preloading modules in the forkserver.

.. date: 2025-06-10-21-00-48 .. gh-issue: 126631 .. nonce: eITVJd .. section: Library

Fix :mod:multiprocessing forkserver bug which prevented __main__ from being preloaded.

.. date: 2025-06-10-16-11-00 .. gh-issue: 133967 .. nonce: P0c24q .. section: Library

Do not normalize :mod:locale name 'C.UTF-8' to 'en_US.UTF-8'.

.. date: 2025-06-10-10-22-18 .. gh-issue: 130870 .. nonce: JipqbO .. section: Library

Preserve :class:types.GenericAlias subclasses in :func:typing.get_type_hints

.. date: 2025-06-10-00-42-30 .. gh-issue: 135321 .. nonce: UHh9jT .. section: Library

Raise a correct exception for values greater than 0x7fffffff for the BINSTRING opcode in the C implementation of :mod:pickle.

.. date: 2025-06-09-10-16-55 .. gh-issue: 121914 .. nonce: G6Avkq .. section: Library

Changed the names of the symbol tables for lambda expressions and generator expressions to "<lambda>" and "<genexpr>" respectively to avoid conflicts with user-defined names.

.. date: 2025-06-08-14-50-34 .. gh-issue: 135276 .. nonce: ZLUhV1 .. section: Library

Synchronized zipfile.Path with zipp 3.23, including improved performance of :meth:zipfile.Path.open for non-reading modes, rely on :func:functools.cached_property to cache values on the instance. Rely on save_method_args to save the initialization method arguments. Fixed .name, .stem and other basename-based properties on Windows when working with a zipfile on disk.

.. date: 2025-06-08-11-11-07 .. gh-issue: 135234 .. nonce: wJCdh0 .. section: Library

:mod:hashlib: improve exception messages when an OpenSSL function failed. When memory allocation fails on OpenSSL's side, a :exc:MemoryError is raised instead of a :exc:ValueError. Patch by Bénédikt Tran.

.. date: 2025-06-08-10-22-22 .. gh-issue: 135244 .. nonce: Y2SOTJ .. section: Library

:mod:uuid: when the MAC address cannot be determined, the 48-bit node ID is now generated with a cryptographically-secure pseudo-random number generator (CSPRNG) as per :rfc:RFC 9562, §6.10.3 <9562#section-6.10-3>. This affects :func:~uuid.uuid1 and :func:~uuid.uuid6.

.. date: 2025-06-08-01-10-34 .. gh-issue: 135241 .. nonce: 5j18IW .. section: Library

The :code:INT opcode of the C accelerator :mod:!_pickle module was updated to look only for "00" and "01" to push booleans onto the stack, aligning with the Python :mod:pickle module.

.. date: 2025-06-06-17-34-18 .. gh-issue: 133934 .. nonce: yT1r68 .. section: Library

Improve :mod:sqlite3 CLI's .help message.

.. date: 2025-06-03-12-59-17 .. gh-issue: 135069 .. nonce: xop30V .. section: Library

Fix the "Invalid error handling" exception in :class:!encodings.idna.IncrementalDecoder to correctly replace the 'errors' parameter.

.. date: 2025-06-02-14-36-28 .. gh-issue: 130662 .. nonce: Gpr2GB .. section: Library

+Accept leading zeros in precision and width fields for +:class:~decimal.Decimal formatting, for example format(Decimal(1.25), '.016f').

.. date: 2025-06-02-14-28-30 .. gh-issue: 130662 .. nonce: EIgIR8 .. section: Library

Accept leading zeros in precision and width fields for :class:~fractions.Fraction formatting, for example format(Fraction(1, 3), '.016f').

.. date: 2025-06-01-14-18-48 .. gh-issue: 135004 .. nonce: cq3-fp .. section: Library

Rewrite and cleanup the internal :mod:!_blake2 module. Some exception messages were changed but their types were left untouched. Patch by Bénédikt Tran.

.. date: 2025-06-01-11-14-00 .. gh-issue: 134953 .. nonce: ashdfs .. section: Library

Expand _colorize theme with keyword_constant and implement in :term:repl.

.. date: 2025-05-31-15-49-46 .. gh-issue: 134978 .. nonce: mXXuvW .. section: Library

:mod:hashlib: Supporting the string keyword parameter in hash function constructors such as :func:~hashlib.new or the direct hash-named constructors such as :func:~hashlib.md5 and :func:~hashlib.sha256 is now deprecated and slated for removal in Python 3.19. Prefer passing the initial data as a positional argument for maximum backwards compatibility. Patch by Bénédikt Tran.

.. date: 2025-05-31-12-08-12 .. gh-issue: 134970 .. nonce: lgSaxq .. section: Library

Fix the "unknown action" exception in :meth:argparse.ArgumentParser.add_argument_group to correctly replace the action class.

.. date: 2025-05-30-18-13-48 .. gh-issue: 134718 .. nonce: 5FEspx .. section: Library

By default, omit optional Load() values in :func:ast.dump.

.. date: 2025-05-30-13-07-29 .. gh-issue: 134718 .. nonce: 9Qvhxn .. section: Library

:func:ast.dump now only omits None and [] values if they are default values.

.. date: 2025-05-30-09-46-21 .. gh-issue: 134939 .. nonce: Pu3nnm .. section: Library

Add the :mod:concurrent.interpreters module. See :pep:734.

.. date: 2025-05-29-17-39-13 .. gh-issue: 108885 .. nonce: MegCRA .. section: Library

Run each example as a subtest in unit tests synthesized by :func:doctest.DocFileSuite and :func:doctest.DocTestSuite. Add the :meth:doctest.DocTestRunner.report_skip method.

.. date: 2025-05-29-06-53-40 .. gh-issue: 134885 .. nonce: -_L22o .. section: Library

Fix possible crash in the :mod:compression.zstd module related to setting parameter types. Patch by Jelle Zijlstra.

.. date: 2025-05-28-20-49-29 .. gh-issue: 134857 .. nonce: dVYXVO .. section: Library

Improve error report for :mod:doctest\ s run with :mod:unittest. Remove :mod:!doctest module frames from tracebacks and redundant newline character from a failure message.

.. date: 2025-05-28-15-53-27 .. gh-issue: 128840 .. nonce: Nur2pB .. section: Library

Fix parsing long IPv6 addresses with embedded IPv4 address.

.. date: 2025-05-27-11-24-38 .. gh-issue: 133579 .. nonce: WGPUC1 .. section: Library

:mod:curses: Consistently report failures of curses C API calls in module-level methods by raising a :exc:curses.error. This affects :func:~curses.assume_default_colors, :func:~curses.baudrate, :func:~curses.cbreak, :func:~curses.echo, :func:~curses.longname, :func:~curses.initscr, :func:~curses.nl, :func:~curses.raw, :func:~curses.termattrs, :func:~curses.termname and :func:~curses.unctrl. Patch by Bénédikt Tran.

.. date: 2025-05-27-11-18-13 .. gh-issue: 133579 .. nonce: ohtgdC .. section: Library

:meth:curses.window.refresh and :meth:curses.window.noutrefresh now raise a :exc:TypeError instead of :exc:curses.error when called with an incorrect number of arguments for :ref:pads <windows-and-pads>. Patch by Bénédikt Tran.

.. date: 2025-05-27-11-13-51 .. gh-issue: 133579 .. nonce: KY9M6S .. section: Library

:ref:curses.window <curses-window-objects>: Consistently report failures of curses C API calls in Window methods by raising a :exc:curses.error. This affects :meth:~curses.window.addch, :meth:~curses.window.addnstr, :meth:~curses.window.addstr, :meth:~curses.window.border, :meth:~curses.window.box, :meth:~curses.window.chgat, :meth:~curses.window.getbkgd, :meth:~curses.window.inch, :meth:~curses.window.insstr and :meth:~curses.window.insnstr. Patch by Bénédikt Tran.

.. date: 2025-05-26-22-18-32 .. gh-issue: 134771 .. nonce: RKXpLT .. section: Library

The time_clockid_converter() function now selects correct type for clockid_t on Cygwin which fixes a build error.

.. date: 2025-05-26-17-06-40 .. gh-issue: 134637 .. nonce: 9-3zRL .. section: Library

Fix performance regression in calling a :mod:ctypes function pointer in :term:free threading.

.. date: 2025-05-26-14-04-39 .. gh-issue: 134696 .. nonce: P04xUa .. section: Library

Built-in HACL* and OpenSSL implementations of hash function constructors now correctly accept the same documented named arguments. For instance, :func:~hashlib.md5 could be previously invoked as md5(data=data) or md5(string=string) depending on the underlying implementation but these calls were not compatible. Patch by Bénédikt Tran.

.. date: 2025-05-26-12-31-08 .. gh-issue: 132710 .. nonce: ApU3TZ .. section: Library

If possible, ensure that :func:uuid.getnode returns the same result even across different processes. Previously, the result was constant only within the same process. Patch by Bénédikt Tran.

.. date: 2025-05-26-11-01-54 .. gh-issue: 134531 .. nonce: my1Fzt .. section: Library

:mod:!_hashlib: Rename internal C functions for :class:!_hashlib.HASH and :class:!_hashlib.HASHXOF objects. Patch by Bénédikt Tran.

.. date: 2025-05-26-10-52-27 .. gh-issue: 134698 .. nonce: aJ1mZ1 .. section: Library

Fix a crash when calling methods of :class:ssl.SSLContext or :class:ssl.SSLSocket across multiple threads.

.. date: 2025-05-25-23-23-05 .. gh-issue: 134151 .. nonce: 13Wwsb .. section: Library

:mod:email: Fix :exc:TypeError in :func:email.utils.decode_params when sorting :rfc:2231 continuations that contain an unnumbered section.

.. date: 2025-05-25-13-46-37 .. gh-issue: 134635 .. nonce: ZlPrlX .. section: Library

:mod:zlib: Allow to combine Adler-32 and CRC-32 checksums via :func:~zlib.adler32_combine and :func:~zlib.crc32_combine. Patch by Callum Attryde and Bénédikt Tran.

.. date: 2025-05-25-11-02-05 .. gh-issue: 134657 .. nonce: 3YFhR9 .. section: Library

:mod:asyncio: Remove some private names from asyncio.__all__.

.. date: 2025-05-24-13-10-35 .. gh-issue: 134210 .. nonce: 0IuMY2 .. section: Library

:func:curses.window.getch now correctly handles signals. Patch by Bénédikt Tran.

.. date: 2025-05-24-03-10-36 .. gh-issue: 80334 .. nonce: z21cMa .. section: Library

:func:multiprocessing.freeze_support now checks for work on any "spawn" start method platform rather than only on Windows.

.. date: 2025-05-23-23-43-39 .. gh-issue: 134582 .. nonce: 9POq3l .. section: Library

Fix tokenize.untokenize() round-trip errors related to t-strings braces escaping

.. date: 2025-05-23-20-01-52 .. gh-issue: 134580 .. nonce: xnaJ70 .. section: Library

Improved the styling of HTML diff pages generated by the :class:difflib.HtmlDiff class, and migrated the output to the HTML5 standard.

.. date: 2025-05-23-10-15-36 .. gh-issue: 134565 .. nonce: zmb66C .. section: Library

:func:unittest.doModuleCleanups no longer swallows all but first exception raised in the cleanup code, but raises a :exc:ExceptionGroup if multiple errors occurred.

.. date: 2025-05-22-18-14-13 .. gh-issue: 134546 .. nonce: fjLVzK .. section: Library

Ensure :mod:pdb remote debugging script is readable by remote Python process.

.. date: 2025-05-22-14-12-53 .. gh-issue: 134451 .. nonce: M1rD-j .. section: Library

Converted asyncio.tools.CycleFoundException from dataclass to a regular exception type.

.. date: 2025-05-22-13-10-32 .. gh-issue: 114177 .. nonce: 3TYUJ3 .. section: Library

Fix :mod:asyncio to not close subprocess pipes which would otherwise error out when the event loop is already closed.

.. date: 2025-05-20-21-45-58 .. gh-issue: 90871 .. nonce: Gkvtp6 .. section: Library

Fixed an off by one error concerning the backlog parameter in :meth:~asyncio.loop.create_unix_server. Contributed by Christian Harries.

.. date: 2025-05-20-19-16-30 .. gh-issue: 134323 .. nonce: ZQZGvw .. section: Library

Fix the :meth:threading.RLock.locked method.

.. date: 2025-05-20-15-13-43 .. gh-issue: 86802 .. nonce: trF7TM .. section: Library

Fixed asyncio memory leak in cancelled shield tasks. For shielded tasks where the shield was cancelled, log potential exceptions through the exception handler. Contributed by Christian Harries.

.. date: 2025-05-20-11-51-17 .. gh-issue: 71189 .. nonce: 0LpTB1 .. section: Library

Add support of the all-but-last mode in :func:os.path.realpath.

.. date: 2025-05-20-11-35-08 .. gh-issue: 72902 .. nonce: jzEI-E .. section: Library

Improve speed (x1.1-1.8) of the :class:~fractions.Fraction constructor for typical inputs (:class:float's, :class:~decimal.Decimal's or strings).

.. date: 2025-05-19-20-59-06 .. gh-issue: 134209 .. nonce: anhTcF .. section: Library

:mod:curses: The :meth:curses.window.instr and :meth:curses.window.getstr methods now allocate their internal buffer on the heap instead of the stack; in addition, the max buffer size is increased from 1023 to 2047.

.. date: 2025-05-19-18-12-42 .. gh-issue: 88994 .. nonce: 7avvVu .. section: Library

Change :func:datetime.datetime.now to half-even rounding for consistency with :func:datetime.datetime.fromtimestamp. Patch by John Keith Hohm.

.. date: 2025-05-19-17-27-21 .. gh-issue: 80184 .. nonce: LOkbaw .. section: Library

The default queue size is now socket.SOMAXCONN for :class:socketserver.TCPServer.

.. date: 2025-05-19-15-30-00 .. gh-issue: 132983 .. nonce: asdsfs .. section: Library

Add :mod:!compression.zstd version information to test.pythoninfo.

.. date: 2025-05-19-15-05-24 .. gh-issue: 134235 .. nonce: pz9PwV .. section: Library

Updated tab completion on REPL to include builtin modules. Contributed by Tom Wang, Hunter Young

.. date: 2025-05-19-10-32-11 .. gh-issue: 134152 .. nonce: INJC2j .. section: Library

Fixed :exc:UnboundLocalError that could occur during :mod:email header parsing if an expected trailing delimiter is missing in some contexts.

.. date: 2025-05-18-23-46-21 .. gh-issue: 134152 .. nonce: 30HwbX .. section: Library

:mod:email: Fix parsing of email message ID with invalid domain.

.. date: 2025-05-18-13-23-29 .. gh-issue: 134168 .. nonce: hgx3Xg .. section: Library

:mod:http.server: Fix IPv6 address binding and :option:--directory <http.server --directory> handling when using HTTPS.

.. date: 2025-05-18-12-48-39 .. gh-issue: 62184 .. nonce: y11l10 .. section: Library

Remove import of C implementation of :class:io.FileIO from Python implementation which has its own implementation

.. date: 2025-05-18-12-23-07 .. gh-issue: 134087 .. nonce: HilZWl .. section: Library

Remove support for arbitrary positional or keyword arguments in the C implementation of :class:threading.RLock objects. This was deprecated since Python 3.14. Patch by Bénédikt Tran.

.. date: 2025-05-18-07-25-15 .. gh-issue: 134173 .. nonce: 53oOoF .. section: Library

Speed up :mod:asyncio performance of transferring state from thread pool :class:concurrent.futures.Future by up to 4.4x. Patch by J. Nick Koston.

.. date: 2025-05-17-20-23-57 .. gh-issue: 133982 .. nonce: smS7au .. section: Library

Emit :exc:RuntimeWarning in the Python implementation of :mod:io when the :term:file-like object <file object> is not closed explicitly in the presence of multiple I/O layers.

.. date: 2025-05-17-18-08-35 .. gh-issue: 133890 .. nonce: onn9_X .. section: Library

The :mod:tarfile module now handles :exc:UnicodeEncodeError in the same way as :exc:OSError when cannot extract a member.

.. date: 2025-05-17-13-46-20 .. gh-issue: 134097 .. nonce: fgkjE1 .. section: Library

Fix interaction of the new :term:REPL and :option:-X showrefcount <-X> command line option.

.. date: 2025-05-17-12-40-12 .. gh-issue: 133889 .. nonce: Eh-zO4 .. section: Library

The generated directory listing page in :class:http.server.SimpleHTTPRequestHandler now only shows the decoded path component of the requested URL, and not the query and fragment.

.. date: 2025-05-16-20-10-25 .. gh-issue: 134098 .. nonce: YyTkKr .. section: Library

Fix handling paths that end with a percent-encoded slash (%2f or %2F) in :class:http.server.SimpleHTTPRequestHandler.

.. date: 2025-05-16-12-40-37 .. gh-issue: 132124 .. nonce: T_5Odx .. section: Library

On POSIX-compliant systems, :func:!multiprocessing.util.get_temp_dir now ignores :envvar:TMPDIR (and similar environment variables) if the path length of AF_UNIX socket files exceeds the platform-specific maximum length when using the :ref:forkserver <multiprocessing-start-method-forkserver> start method. Patch by Bénédikt Tran.

.. date: 2025-05-15-14-27-01 .. gh-issue: 134062 .. nonce: fRbJet .. section: Library

:mod:ipaddress: fix collisions in :meth:~object.__hash__ for :class:~ipaddress.IPv4Network and :class:~ipaddress.IPv6Network objects.

.. date: 2025-05-15-00-27-09 .. gh-issue: 134004 .. nonce: e8k4-R .. section: Library

:mod:shelve as well as underlying :mod:!dbm.dumb and :mod:!dbm.sqlite now have :meth:!reorganize methods to recover unused free space previously occupied by deleted entries.

.. date: 2025-05-13-18-54-56 .. gh-issue: 133970 .. nonce: 6G-Oi6 .. section: Library

Make :class:!string.templatelib.Template and :class:!string.templatelib.Interpolation generic.

.. date: 2025-05-13-18-21-59 .. gh-issue: 71253 .. nonce: -3Sf_K .. section: Library

Raise :exc:ValueError in :func:open if opener returns a negative file-descriptor in the Python implementation of :mod:io to match the C implementation.

.. date: 2025-05-12-20-38-57 .. gh-issue: 133960 .. nonce: Aee79f .. section: Library

Simplify and improve :func:typing.evaluate_forward_ref. It now no longer raises errors on certain invalid types. In several situations, it is now able to evaluate forward references that were previously unsupported.

.. date: 2025-05-12-06-52-10 .. gh-issue: 133925 .. nonce: elInBY .. section: Library

Make the private class typing._UnionGenericAlias hashable.

.. date: 2025-05-11-12-56-52 .. gh-issue: 133604 .. nonce: kFxhc8 .. section: Library

Remove :func:!platform.java_ver which was deprecated since Python 3.13.

.. date: 2025-05-11-11-39-05 .. gh-issue: 133875 .. nonce: pUar3l .. section: Library

Removed deprecated :meth:!pathlib.PurePath.is_reserved. Use :func:os.path.isreserved to detect reserved paths on Windows.

.. date: 2025-05-11-10-28-11 .. gh-issue: 133873 .. nonce: H03nov .. section: Library

Remove the deprecated getmark(), setmark() and getmarkers() methods of the :class:~wave.Wave_read and :class:~wave.Wave_write classes, which were deprecated since Python 3.13. Patch by Bénédikt Tran.

.. date: 2025-05-11-10-01-48 .. gh-issue: 133866 .. nonce: g3dHP_ .. section: Library

Remove the undocumented function :func:!ctypes.SetPointerType, which has been deprecated since Python 3.13. Patch by Bénédikt Tran.

.. date: 2025-05-11-08-48-55 .. gh-issue: 133823 .. nonce: F8udQy .. section: Library

Remove support for TD = TypedDict("TD") and TD = TypedDict("TD", None) calls for constructing :class:typing.TypedDict objects with zero field. Patch by Bénédikt Tran.

.. date: 2025-05-10-17-42-03 .. gh-issue: 125996 .. nonce: vaQp0- .. section: Library

Fix thread safety of :class:collections.OrderedDict. Patch by Kumar Aditya.

.. date: 2025-05-10-12-07-54 .. gh-issue: 133817 .. nonce: 4GMtKV .. section: Library

Remove support for creating :class:~typing.NamedTuple classes via the undocumented keyword argument syntax. Patch by Bénédikt Tran.

.. date: 2025-05-10-12-06-55 .. gh-issue: 133653 .. nonce: Gb2aG4 .. section: Library

Fix :class:argparse.ArgumentParser with the formatter_class argument. Fix TypeError when formatter_class is a custom subclass of :class:!HelpFormatter. Fix TypeError when formatter_class is not a subclass of :class:!HelpFormatter and non-standard prefix_char is used. Fix support of colorizing when formatter_class is not a subclass of :class:!HelpFormatter.

.. date: 2025-05-10-11-04-47 .. gh-issue: 133810 .. nonce: 03WhnK .. section: Library

Remove :class:!http.server.CGIHTTPRequestHandler and --cgi flag from the :program:python -m http.server command-line interface. They were deprecated in Python 3.13. Patch by Bénédikt Tran.

.. date: 2025-05-09-20-59-24 .. gh-issue: 132641 .. nonce: 3qTw44 .. section: Library

Fixed a race in :func:functools.lru_cache under free-threading.

.. date: 2025-05-09-19-05-24 .. gh-issue: 133783 .. nonce: 1voCnR .. section: Library

Fix bug with applying :func:copy.replace to :mod:ast objects. Attributes that default to None were incorrectly treated as required for manually created AST nodes.

.. date: 2025-05-09-18-29-25 .. gh-issue: 133684 .. nonce: Y1DFSt .. section: Library

Fix bug where :func:annotationlib.get_annotations would return the wrong result for certain classes that are part of a class hierarchy where from __future__ import annotations is used.

.. date: 2025-05-09-15-50-00 .. gh-issue: 77057 .. nonce: fV8SU- .. section: Library

Fix handling of invalid markup declarations in :class:html.parser.HTMLParser.

.. date: 2025-05-09-09-10-34 .. gh-issue: 130328 .. nonce: s9h4By .. section: Library

Speedup pasting in PyREPL on Windows in a legacy console. Patch by Chris Eibl.

.. date: 2025-05-09-08-49-03 .. gh-issue: 133701 .. nonce: KI8tGz .. section: Library

Fix bug where :class:typing.TypedDict classes defined under from __future__ import annotations and inheriting from another TypedDict had an incorrect __annotations__ attribute.

.. date: 2025-05-08-20-45-35 .. gh-issue: 133656 .. nonce: cxZODA .. section: Library

Remove deprecated :meth:!zipimport.zipimporter.load_module. Use :meth:zipimport.zipimporter.exec_module instead.

.. date: 2025-05-08-20-03-20 .. gh-issue: 133722 .. nonce: 1-B82a .. section: Library

Added a color option to :func:difflib.unified_diff that colors output similar to :program:git diff.

.. date: 2025-05-08-13-43-19 .. gh-issue: 133489 .. nonce: 9eGS1Z .. section: Library

:func:random.getrandbits can now generate more that 2\ :sup:31 bits. :func:random.randbytes can now generate more that 256 MiB.

.. date: 2025-05-07-22-15-15 .. gh-issue: 133595 .. nonce: c3U88r .. section: Library

Clean up :class:sqlite3.Connection APIs. All parameters of :func:sqlite3.connect except database are now keyword-only. The first three parameters of methods :meth:~sqlite3.Connection.create_function and :meth:~sqlite3.Connection.create_aggregate are now positional-only. The first parameter of methods :meth:~sqlite3.Connection.set_authorizer, :meth:~sqlite3.Connection.set_progress_handler and :meth:~sqlite3.Connection.set_trace_callback is now positional-only.

.. date: 2025-05-07-19-16-41 .. gh-issue: 133581 .. nonce: kERUCJ .. section: Library

Improve unparsing of t-strings in :func:ast.unparse and from __future__ import annotations. Empty t-strings now round-trip correctly and formatting in interpolations is preserved. Patch by Jelle Zijlstra.

.. date: 2025-05-07-14-36-30 .. gh-issue: 133577 .. nonce: BggPk9 .. section: Library

Add parameter formatter to :func:logging.basicConfig.

.. date: 2025-05-07-13-31-06 .. gh-issue: 92897 .. nonce: ubeqGE .. section: Library

Removed the check_home parameter from :func:sysconfig.is_python_build, deprecated since Python 3.12.

.. date: 2025-05-06-22-54-37 .. gh-issue: 133551 .. nonce: rfy1tJ .. section: Library

Support t-strings (:pep:750) in :mod:annotationlib. Patch by Jelle Zijlstra.

.. date: 2025-05-06-14-44-55 .. gh-issue: 133517 .. nonce: Ca6NgW .. section: Library

Remove :func:os.listdrives, :func:os.listvolumes and :func:os.listmounts in non Windows desktop builds since the underlying functionality is missing.

.. date: 2025-05-05-22-11-24 .. gh-issue: 133439 .. nonce: LpmyFz .. section: Library

Fix dot commands with trailing spaces are mistaken for multi-line SQL statements in the sqlite3 command-line interface.

.. date: 2025-05-05-18-50-00 .. gh-issue: 133447 .. nonce: ajshdb .. section: Library

Add basic color to :mod:sqlite3 CLI interface.

.. date: 2025-05-05-10-41-41 .. gh-issue: 133253 .. nonce: J5-xDD .. section: Library

Fix thread-safety issues in :mod:linecache.

.. date: 2025-05-05-03-14-08 .. gh-issue: 133390 .. nonce: AuTggn .. section: Library

Support keyword completion in the :mod:sqlite3 command-line interface and add :data:sqlite3.SQLITE_KEYWORDS constant.

.. date: 2025-05-04-17-04-55 .. gh-issue: 132493 .. nonce: huirKi .. section: Library

Avoid accessing __annotations__ unnecessarily in :func:inspect.signature.

.. date: 2025-05-01-16-03-11 .. gh-issue: 133017 .. nonce: k7RLQp .. section: Library

Improve the error message of :func:multiprocessing.sharedctypes.Array, :func:multiprocessing.sharedctypes.RawArray, :func:multiprocessing.sharedctypes.Value and :func:multiprocessing.sharedctypes.RawValue when an invalid typecode is passed. Patch by Tomas Roun

.. date: 2025-05-01-10-56-44 .. gh-issue: 132813 .. nonce: rKurvp .. section: Library

Improve error messages for incorrect types and values of :class:csv.Dialect attributes.

.. date: 2025-04-30-19-32-18 .. gh-issue: 132969 .. nonce: EagQ3G .. section: Library

Prevent the :class:~concurrent.futures.ProcessPoolExecutor executor thread, which remains running when :meth:shutdown(wait=False) <concurrent.futures.Executor.shutdown>, from attempting to adjust the pool's worker processes after the object state has already been reset during shutdown. A combination of conditions, including a worker process having terminated abormally, resulted in an exception and a potential hang when the still-running executor thread attempted to replace dead workers within the pool.

.. date: 2025-04-29-11-48-46 .. gh-issue: 132876 .. nonce: lyTQGZ .. section: Library

ldexp() on Windows doesn't round subnormal results before Windows 11, but should. Python's :func:math.ldexp wrapper now does round them, so results may change slightly, in rare cases of very small results, on Windows versions before 11.

.. date: 2025-04-26-15-50-12 .. gh-issue: 133009 .. nonce: etBuz5 .. section: Library

:mod:xml.etree.ElementTree: Fix a crash in :meth:Element.__deepcopy__ <object.__deepcopy__> when the element is concurrently mutated. Patch by Bénédikt Tran.

.. date: 2025-04-25-16-06-53 .. gh-issue: 132908 .. nonce: wV5rja .. section: Library

Add :func:math.isnormal and :func:math.issubnormal functions. Patch by Sergey B Kirpichev.

.. date: 2025-04-25-11-53-37 .. gh-issue: 95380 .. nonce: 7dvPe- .. section: Library

:func:fcntl.fcntl and :func:fcntl.ioctl: Remove the 1024 bytes limit on the size of not mutated bytes-like argument.

.. date: 2025-04-25-11-48-00 .. gh-issue: 122781 .. nonce: ajsdns .. section: Library

Fix %z directive in :func:datetime.datetime.strptime to allow for no provided offset as was documented.

.. date: 2025-04-22-21-00-23 .. gh-issue: 123471 .. nonce: asOLA2 .. section: Library

Make concurrent iterations over :class:itertools.combinations and :class:itertools.product safe under free-threading.

.. date: 2025-04-21-01-05-14 .. gh-issue: 127081 .. nonce: Egrpq7 .. section: Library

Fix libc thread safety issues with :mod:dbm by performing stateful operations in critical sections.

.. date: 2025-04-21-01-03-15 .. gh-issue: 127081 .. nonce: WXRliX .. section: Library

Fix libc thread safety issues with :mod:os by replacing getlogin with getlogin_r re-entrant version.

.. date: 2025-04-21-00-58-04 .. gh-issue: 127081 .. nonce: 3DCl92 .. section: Library

Fix libc thread safety issues with :mod:pwd by locking access to getpwall.

.. date: 2025-04-16-21-02-57 .. gh-issue: 132551 .. nonce: Psa7pL .. section: Library

Make :class:io.BytesIO safe in :term:free-threaded <free threading> build.

.. date: 2025-04-08-07-25-10 .. gh-issue: 107583 .. nonce: JGfbhq .. section: Library

Fix :class:!Flag inversion when flag set has missing values (:class:!IntFlag still flips all bits); fix negative assigned values during flag creation (both :class:!Flag and :class:!IntFlag ignore missing values).

.. date: 2025-04-07-10-20-16 .. gh-issue: 87790 .. nonce: X2SjJe .. section: Library

Support underscore and comma as thousands separators in the fractional part for :class:~fractions.Fraction's formatting. Patch by Sergey B Kirpichev.

.. date: 2025-04-07-09-53-54 .. gh-issue: 87790 .. nonce: 6nj3zQ .. section: Library

Support underscore and comma as thousands separators in the fractional part for :class:~decimal.Decimal's formatting. Patch by Sergey B Kirpichev.

.. date: 2025-04-07-06-41-54 .. gh-issue: 131884 .. nonce: ym9BJN .. section: Library

Fix formatting issues in :func:json.dump when both indent and skipkeys are used.

.. date: 2025-03-27-08-13-32 .. gh-issue: 131788 .. nonce: 0RWiFc .. section: Library

Make ResourceTracker.send from :mod:multiprocessing re-entrant safe

.. date: 2025-03-19-12-41-42 .. gh-issue: 91349 .. nonce: 8eTOCP .. section: Library

Adjust default compressionlevel= to 6 (down from 9) in :mod:gzip and :mod:tarfile. It is the default level used by most compression tools and a better tradeoff between speed and performance.

.. date: 2025-03-17-21-21-06 .. gh-issue: 131146 .. nonce: A5Obgv .. section: Library

Fix :class:calendar.TextCalendar, :class:calendar.HTMLCalendar, and the :mod:calendar CLI to display month names in the nominative case by adding :data:calendar.standalone_month_name and :data:calendar.standalone_month_abbr, which provide month names and abbreviations in the grammatical form used when a month name stands by itself, if the locale supports it.

.. date: 2025-03-13-20-48-58 .. gh-issue: 123471 .. nonce: cM4w4f .. section: Library

Make concurrent iterations over :class:itertools.cycle safe under free-threading.

.. date: 2025-03-11-05-24-14 .. gh-issue: 130664 .. nonce: g0yNMm .. section: Library

Handle corner-case for :class:~fractions.Fraction's formatting: treat zero-padding (preceding the width field by a zero ('0') character) as an equivalent to a fill character of '0' with an alignment type of '=', just as in case of :class:float's.

.. date: 2025-03-09-03-13-41 .. gh-issue: 130999 .. nonce: tBRBVB .. section: Library

Avoid exiting the new REPL and offer suggestions even if there are non-string candidates when errors occur.

.. date: 2025-03-08-17-07-00 .. gh-issue: 88473 .. nonce: qg23g8 .. section: Library

Implement a fast path for :class:datetime.date objects in :func:datetime.date.today which results in a 5x performance gain while proper subclasses retain their previous performance.

.. date: 2024-11-25-10-22-08 .. gh-issue: 126883 .. nonce: MAEF7g .. section: Library

Add check that timezone fields are in range for :meth:datetime.datetime.fromisoformat and :meth:datetime.time.fromisoformat. Patch by Semyon Moroz.

.. date: 2024-10-28-06-54-22 .. gh-issue: 125028 .. nonce: GEY8Ws .. section: Library

:data:functools.Placeholder cannot be passed to :func:functools.partial as a keyword argument.

.. date: 2024-10-22-16-21-55 .. gh-issue: 125843 .. nonce: 2ttzYo .. section: Library

If possible, indicate which :mod:curses C function or macro is responsible for raising a :exc:curses.error exception. Patch by Bénédikt Tran.

.. date: 2024-10-17-01-12-22 .. gh-issue: 119109 .. nonce: u4hcvb .. section: Library

:func:functools.partial calls are now faster when keyword arguments are used.

.. date: 2024-09-13-09-48-25 .. gh-issue: 124033 .. nonce: WNudS0 .. section: Library

SimplePath is now presented in importlib.metadata.__all__.

.. date: 2024-09-13-09-46-47 .. gh-issue: 91216 .. nonce: LuOsF4 .. section: Library

importlib.metadata now raises a KeyError instead of returning None when a key is missing from the metadata.

.. date: 2024-09-13-09-43-15 .. gh-issue: 120492 .. nonce: Mm6CJ6 .. section: Library

importlib.metadata now prioritizes valid dists to invalid dists when retrieving by name.

.. date: 2024-07-16-00-01-04 .. gh-issue: 99631 .. nonce: GWD4fD .. section: Library

The :mod:shelve module now accepts custom serialization and deserialization functions.

.. date: 2024-07-06-14-32-30 .. gh-issue: 119186 .. nonce: E5B1HQ .. section: Library

Slightly speed up :func:os.walk by calling :func:os.path.join less often.

.. date: 2024-06-06-17-49-07 .. gh-issue: 120170 .. nonce: DUxhmT .. section: Library

Fix an issue in the :mod:!_pickle extension module in which importing :mod:multiprocessing could change how pickle identifies which module an object belongs to, potentially breaking the unpickling of those objects.

.. date: 2024-05-13-09-50-31 .. gh-issue: 118981 .. nonce: zgOQPv .. section: Library

Fix potential hang in multiprocessing.popen_spawn_posix that can happen when the child proc dies early by closing the child fds right away.

.. date: 2023-07-05-14-34-10 .. gh-issue: 105497 .. nonce: HU5u89 .. section: Library

Fix flag mask inversion when unnamed flags exist.

.. date: 2023-03-13-22-51-40 .. gh-issue: 99813 .. nonce: 40TV02 .. section: Library

:mod:ssl now uses SSL_sendfile internally when it is possible (see :data:~ssl.OP_ENABLE_KTLS). The function sends a file more efficiently because it performs TLS encryption in the kernel to avoid additional context switches. Patch by Illia Volochii.

.. date: 2023-02-13-21-56-38 .. gh-issue: 62824 .. nonce: CBZzX3 .. section: Library

Fix aliases for iso8859_8 encoding. Patch by Dave Goncalves.

.. date: 2023-02-13-21-41-34 .. gh-issue: 86155 .. nonce: ppIGSC .. section: Library

:meth:html.parser.HTMLParser.close no longer loses data when the <script> tag is not closed. Patch by Waylan Limberg.

.. date: 2023-02-13-20-34-52 .. gh-issue: 78319 .. nonce: V1zzed .. section: Library

UTF8 support for the IMAP APPEND command has been made RFC compliant.

.. date: 2022-10-08-14-56-07 .. gh-issue: 93334 .. nonce: 0KUm8d .. section: Library

Reraise :exc:KeyError as :exc:ModuleNotFoundError when :meth:importlib.machinery.PathFinder.find_spec is called on a submodule without importing the parent (and without a path argument).

.. date: 2022-07-24-20-56-32 .. gh-issue: 69426 .. nonce: unccw7 .. section: Library

Fix :class:html.parser.HTMLParser to not unescape character entities in attribute values if they are followed by an ASCII alphanumeric or an equals sign.

.. bpo: 38735 .. date: 2022-01-07-16-56-57 .. nonce: NFfJX6 .. section: Library

Fix failure when importing a module from the root directory on unix-like platforms with sys.pycache_prefix set.

.. bpo: 45959 .. date: 2021-12-18-12-46-20 .. nonce: vPlr3P .. section: Library

:mod:pprint can now pretty-print dict views.

.. date: 2021-09-21-17-17-29 .. gh-issue: 84683 .. nonce: wDSRsG .. section: Library

:mod:zoneinfo: Check in <prefix>/share/zoneinfo for data files on Windows

.. bpo: 43429 .. date: 2021-03-07-16-31-36 .. nonce: Koa0mf .. section: Library

The :meth:~mmap.mmap.size method of the :class:mmap.mmap class now returns the size of an anonymous mapping on both Unix and Windows. Previously, the size would be returned on Windows and an :exc:OSError would be raised on Unix. :exc:ValueError is now raised instead of :exc:OSError when trackfd=False.

.. bpo: 41839 .. date: 2020-09-23-11-54-17 .. nonce: kU5Ywl .. section: Library

Allow negative priority values from :func:os.sched_get_priority_min and :func:os.sched_get_priority_max functions.

.. bpo: 28494 .. date: 2017-12-30-18-21-00 .. nonce: Dt_Wks .. section: Library

Improve Zip file validation false positive rate in :func:zipfile.is_zipfile.

.. date: 2025-10-09-12-53-47 .. gh-issue: 96491 .. nonce: 4YKxvy .. section: IDLE

Deduplicate version number in IDLE shell title bar after saving to a file.

.. date: 2025-10-08-08-35-50 .. gh-issue: 139742 .. nonce: B3fZLg .. section: IDLE

Colorize t-string prefixes for template strings in IDLE, as done for f-string prefixes.

.. date: 2025-07-01-23-00-58 .. gh-issue: 136155 .. nonce: 4siQQO .. section: Documentation

We are now checking for fatal errors in EPUB builds in CI.

.. date: 2025-06-10-17-02-06 .. gh-issue: 135171 .. nonce: quHvts .. section: Documentation

Document that the :term:iterator for the leftmost :keyword:!for clause in the generator expression is created immediately.

.. bpo: 45210 .. date: 2021-09-15-13-07-25 .. nonce: RtGk7i .. section: Documentation

Document that error indicator may be set in tp_dealloc, and how to avoid clobbering it.

.. date: 2025-10-13-17-56-23 .. gh-issue: 140000 .. nonce: tLhn3e .. section: Core and Builtins

Fix potential memory leak when a reference cycle exists between an instance of :class:typing.TypeAliasType, :class:typing.TypeVar, :class:typing.ParamSpec, or :class:typing.TypeVarTuple and its __name__ attribute. Patch by Mikhail Efimov.

.. date: 2025-10-12-18-54-06 .. gh-issue: 140009 .. nonce: -MbFh_ .. section: Core and Builtins

Improve performance of list extension by dictionary items.

.. date: 2025-10-12-11-00-06 .. gh-issue: 139988 .. nonce: 4wi51t .. section: Core and Builtins

Fix a memory leak when failing to create a :class:~typing.Union type. Patch by Bénédikt Tran.

.. date: 2025-10-08-13-52-00 .. gh-issue: 139748 .. nonce: jq0yFJ .. section: Core and Builtins

Fix reference leaks in error branches of functions accepting path strings or bytes such as :func:compile and :func:os.system. Patch by Bénédikt Tran.

.. date: 2025-10-06-13-15-26 .. gh-issue: 139516 .. nonce: d9Pkur .. section: Core and Builtins

Fix lambda colon erroneously start format spec in f-string in tokenizer.

.. date: 2025-10-01-18-21-19 .. gh-issue: 63161 .. nonce: ef1S6N .. section: Core and Builtins

Support non-UTF-8 shebang and comments in Python source files if non-UTF-8 encoding is specified. Detect decoding error in comments for default (UTF-8) encoding. Show the line and position of decoding error for default encoding in a traceback. Show the line containing the coding cookie when it conflicts with the BOM in a traceback.

.. date: 2025-09-30-14-57-19 .. gh-issue: 139116 .. nonce: nlVf40 .. section: Core and Builtins

Prevent a deadlock when multiple threads start, stop and use :mod:tracemalloc simultaneously.

.. date: 2025-09-24-17-32-52 .. gh-issue: 139275 .. nonce: novrqf .. section: Core and Builtins

Fix compilation problems in _remote_debugging_module.c when the system doesn't have process_vm_readv. Patch by Pablo Galindo

.. date: 2025-09-24-17-08-42 .. gh-issue: 133059 .. nonce: EXvxb7 .. section: Core and Builtins

Increased the number of cached small positive integers from 256 to 1024.

.. date: 2025-09-22-15-21-49 .. gh-issue: 74857 .. nonce: 5XRQaA .. section: Core and Builtins

:pep:538: Coerce the POSIX locale to a UTF-8 based locale. Patch by Victor Stinner.

.. date: 2025-09-21-14-33-17 .. gh-issue: 116738 .. nonce: vNaI4h .. section: Library

Make :mod:mmap thread-safe on the :term:free threaded <free threading> build.

.. date: 2025-09-17-17-17-21 .. gh-issue: 138558 .. nonce: 0VbzCH .. section: Core and Builtins

Fix handling of unusual t-string annotations in annotationlib. Patch by Dave Peck.

.. date: 2025-09-15-14-04-56 .. gh-issue: 134466 .. nonce: yR4fYW .. section: Core and Builtins

Don't run PyREPL in a degraded environment where setting termios attributes is not allowed.

.. date: 2025-09-11-15-56-18 .. gh-issue: 138794 .. nonce: nrOn1K .. section: Core and Builtins

When a new tracing function is registered with :c:func:PyRefTracer_SetTracer, replacing the current a call to the trace function will be made with the object set to NULL and event set to :c:data:PyRefTracer_TRACKER_REMOVED. This will happen just before the new function is registered. Patch by Pablo Galindo

.. date: 2025-09-10-14-53-59 .. gh-issue: 71810 .. nonce: ppf0J- .. section: Core and Builtins

Raise :exc:OverflowError for (-1).to_bytes() for signed conversions when bytes count is zero. Patch by Sergey B Kirpichev.

.. date: 2025-09-09-23-59-13 .. gh-issue: 138716 .. nonce: UawDY0 .. section: Core and Builtins

Improve :exc:SyntaxError message for :keyword:assert in cases like assert a := b.

.. date: 2025-09-06-13-53-33 .. gh-issue: 105487 .. nonce: a43YaY .. section: Core and Builtins

Remove non-existent :meth:~object.__copy__, :meth:~object.__deepcopy__, and :attr:~type.__bases__ from the :meth:~object.__dir__ entries of :class:types.GenericAlias.

.. date: 2025-09-05-01-19-04 .. gh-issue: 138192 .. nonce: erluq5 .. section: Core and Builtins

Fix :mod:contextvars initialization so that all subinterpreters are assigned the :attr:~contextvars.Token.MISSING value.

.. date: 2025-09-03-17-00-30 .. gh-issue: 138479 .. nonce: qUxgWs .. section: Core and Builtins

Fix a crash when a generic object's __typing_subst__ returns an object that isn't a :class:tuple.

.. date: 2025-09-03-15-35-34 .. gh-issue: 138431 .. nonce: EUsrtA .. section: Core and Builtins

Fix a bug in the JIT optimizer when round-tripping strings and tuples.

.. date: 2025-09-03-10-16-09 .. gh-issue: 138378 .. nonce: r6BQxV .. section: Core and Builtins

Move the globals-to-const JIT optimizer pass into to the main JIT optimizer pass

.. date: 2025-09-02-22-17-55 .. gh-issue: 138401 .. nonce: uTRvue .. section: Library

Add missing validation of argument count in :func:os.sendfile to be non-negative.

.. date: 2025-09-02-09-10-06 .. gh-issue: 138372 .. nonce: h1Xk4- .. section: Core and Builtins

Fix :exc:SyntaxWarning emitted for erroneous subscript expressions involving :ref:template string literals <t-strings>. Patch by Brian Schubert.

.. date: 2025-09-01-21-52-54 .. gh-issue: 138302 .. nonce: -ez47B .. section: Core and Builtins

BINARY_OP now specializes to BINARY_OP_ADD_INT, BINARY_OP_SUBTRACT_INT or BINARY_OP_MULTIPLY_INT if operands are compact ints.

.. date: 2025-09-01-16-09-02 .. gh-issue: 138318 .. nonce: t-WEN5 .. section: Core and Builtins

The default REPL now avoids highlighting built-in names (for instance :class:set or :func:format) when they are used as attribute names (for instance in value.set or text.format).

.. date: 2025-09-01-13-54-43 .. gh-issue: 138349 .. nonce: 0fGmAi .. section: Core and Builtins

Fix crash in certain cases where a module contains both a module-level annotation and a comprehension.

.. date: 2025-08-30-17-15-05 .. gh-issue: 69605 .. nonce: KjBk99 .. section: Core and Builtins

Fix some standard library submodules missing from the :term:REPL auto-completion of imports.

.. date: 2025-08-30-00-55-35 .. gh-issue: 61206 .. nonce: HeFLvl .. section: Core and Builtins

:mod:zipimport now supports zstandard compressed zip file entries.

.. date: 2025-08-28-09-29-46 .. gh-issue: 116738 .. nonce: yLZJpV .. section: Library

Make :mod:!cProfile thread-safe on the :term:free threaded <free threading> build.

.. date: 2025-08-27-17-51-38 .. gh-issue: 137838 .. nonce: lK6T0j .. section: Core and Builtins

Fix JIT trace buffer overrun by increasing possible exit stubs. Patch by Donghee Na.

.. date: 2025-08-27-13-11-47 .. gh-issue: 71679 .. nonce: V0yFeT .. section: Core and Builtins

Use the same quoting algorithm for the repr of bytearrays as for bytes objects and strings -- use double quotes for quoting if the bytearray contains single quotes and does not contain double quotes.

.. date: 2025-08-22-11-39-40 .. gh-issue: 137384 .. nonce: j4b_in .. section: Core and Builtins

Fix a crash when using the :mod:warnings module in a finalizer at shutdown. Patch by Kumar Aditya.

.. date: 2025-08-21-06-31-42 .. gh-issue: 138004 .. nonce: FH2Hre .. section: Library

On Solaris/Illumos platforms, thread names are now encoded as ASCII to avoid errors on systems (e.g. OpenIndiana) that don't support non-ASCII names.

.. date: 2025-08-21-01-46-39 .. gh-issue: 137976 .. nonce: p4sb4x .. section: Library

Removed localtime from the list of reported system timezones.

.. date: 2025-08-20-14-17-47 .. gh-issue: 137992 .. nonce: fcL3SK .. section: Core and Builtins

Ensure that :c:func:PyRefTracer_SetTracer sync with all existing threads when called to avoid races in the free threaded build. Patch by Pablo Galindo

.. date: 2025-08-19-18-52-22 .. gh-issue: 137967 .. nonce: uw67Ys .. section: Core and Builtins

Show error suggestions on nested attribute access. Patch by Pablo Galindo

.. date: 2025-08-19-16-07-07 .. gh-issue: 137959 .. nonce: EWj0RZ .. section: Core and Builtins

Replace the shim code added to every piece of jitted code with a single trampoline function.

.. date: 2025-08-17-13-36-53 .. gh-issue: 137883 .. nonce: 55VDCN .. section: Core and Builtins

Fix runaway recursion when calling a function with keyword arguments.

.. date: 2025-08-15-15-45-26 .. gh-issue: 137079 .. nonce: YEow69 .. section: Core and Builtins

Fix keyword typo recognition when parsing files. Patch by Pablo Galindo.

.. date: 2025-08-14-14-18-29 .. gh-issue: 137728 .. nonce: HdYS9R .. section: Core and Builtins

Fix the JIT's handling of many local variables. This previously caused a segfault.

.. date: 2025-08-13-16-58-58 .. gh-issue: 137716 .. nonce: ZcZSyi .. section: Core and Builtins

Fix double period in :exc:AttributeError message for invalid mock assertions

.. date: 2025-08-13-13-39-02 .. gh-issue: 137433 .. nonce: g6Atfz .. section: Core and Builtins

Fix a potential deadlock in the :term:free threading build when daemon threads enable or disable profiling or tracing while the main thread is shutting down the interpreter.

.. date: 2025-08-10-21-34-12 .. gh-issue: 137576 .. nonce: 0ZicS- .. section: Core and Builtins

Fix for incorrect source code being shown in tracebacks from the Basic REPL when :envvar:PYTHONSTARTUP is given. Patch by Adam Hartz.

.. date: 2025-08-09-11-38-37 .. gh-issue: 37817 .. nonce: Y5Fhde .. section: Core and Builtins

Allow assignment to :attr:~type.__bases__ of direct subclasses of builtin classes.

.. date: 2025-08-09-04-07-05 .. gh-issue: 132732 .. nonce: 8BiIVJ .. section: Core and Builtins

Optimize _COMPARE_OP, _CONTAINS_OP, _UNARY_NEGATIVE, _UNARY_NOT, and _UNARY_INVERT in JIT builds with constant-loading uops (_POP_TWO_LOAD_CONST_INLINE_BORROW and _POP_TOP_LOAD_CONST_INLINE_BORROW), and then remove both to reduce instruction count.

.. date: 2025-08-07-09-52-19 .. gh-issue: 137400 .. nonce: AK1dy- .. section: Core and Builtins

Fix a crash in the :term:free threading build when disabling profiling or tracing across all threads with :c:func:PyEval_SetProfileAllThreads or :c:func:PyEval_SetTraceAllThreads or their Python equivalents :func:threading.settrace_all_threads and :func:threading.setprofile_all_threads.

.. date: 2025-08-06-16-55-44 .. gh-issue: 133143 .. nonce: l7CI9v .. section: Core and Builtins

Add :data:sys.abi_info object to make ABI information more easily accessible.

.. date: 2025-08-06-15-39-54 .. gh-issue: 137400 .. nonce: xIw0zs .. section: Core and Builtins

.. date: 2025-08-05-20-24-12 .. gh-issue: 120037 .. nonce: MB7MmI .. section: Core and Builtins

Disable user site packages directory when a ._pth file is used, even if it contains import site.

.. date: 2025-08-05-17-22-24 .. gh-issue: 58124 .. nonce: q1__53 .. section: Core and Builtins

Fix name of the Python encoding in Unicode errors of the code page codec: use "cp65000" and "cp65001" instead of "CP_UTF7" and "CP_UTF8" which are not valid Python code names. Patch by Victor Stinner.

.. date: 2025-08-05-10-22-15 .. gh-issue: 136966 .. nonce: J5lrE0 .. section: Core and Builtins

The :attr:object.__dict__ and :attr:!__weakref__ descriptors now use a single descriptor instance per interpreter, shared across all types that need them. This speeds up class creation, and helps avoid reference cycles.

.. date: 2025-08-02-23-04-57 .. gh-issue: 137314 .. nonce: wjEdzD .. section: Core and Builtins

Fixed a regression where raw f-strings incorrectly interpreted escape sequences in format specifications. Raw f-strings now properly preserve literal backslashes in format specs, matching the behavior from Python 3.11. For example, rf"{obj:\xFF}" now correctly produces '\\xFF' instead of 'ÿ'. Patch by Pablo Galindo.

.. date: 2025-08-02-10-27-53 .. gh-issue: 137308 .. nonce: at05p_ .. section: Core and Builtins

A standalone docstring in a node body is optimized as a :keyword:pass statement to ensure that the node's body is never empty. There was a :exc:ValueError in :func:compile otherwise.

.. date: 2025-08-01-18-54-31 .. gh-issue: 137288 .. nonce: FhE7ku .. section: Core and Builtins

Fix bug where some bytecode instructions of a boolean expression are not associated with the correct exception handler.

.. date: 2025-07-31-23-02-02 .. gh-issue: 137291 .. nonce: kIxVZd .. section: Core and Builtins

The perf profiler can now be used if a previous frame evaluation API has been provided.

.. date: 2025-07-28-19-11-34 .. gh-issue: 134291 .. nonce: IiB9Id .. section: Core and Builtins

Remove some newer macOS API usage from the JIT compiler in order to restore compatibility with older OSX 10.15 deployment targets.

.. date: 2025-07-28-17-01-05 .. gh-issue: 88886 .. nonce: g4XFPb .. section: Core and Builtins

The codecs lookup function now again performs only minimal normalization of the encoding name before passing it to the search functions: all ASCII letters are converted to lower case, spaces are replaced with hyphens. This restores the pre-Python 3.9 behavior.

.. date: 2025-07-25-22-31-52 .. gh-issue: 131338 .. nonce: zJDCMp .. section: Core and Builtins

Disable computed stack limit checks on non-glibc linux platforms to fix crashes on deep recursion.

.. date: 2025-07-24-17-30-58 .. gh-issue: 136870 .. nonce: ncx82J .. section: Core and Builtins

Fix data races while de-instrumenting bytecode of code objects running concurrently in threads.

.. date: 2025-07-24-02-13-59 .. gh-issue: 132732 .. nonce: p77xkb .. section: Core and Builtins

Optimize constant comparison for _COMPARE_OP_INT, _COMPARE_OP_FLOAT and _COMPARE_OP_STR in JIT builds

.. date: 2025-07-19-17-08-09 .. gh-issue: 127598 .. nonce: Mx8S-y .. section: Core and Builtins

Improve :exc:ModuleNotFoundError by adding flavour text to the exception when the :option:-S option is passed. Patch by Andrea Mattei.

.. date: 2025-07-19-12-37-05 .. gh-issue: 136801 .. nonce: XU_tF2 .. section: Core and Builtins

Fix PyREPL syntax highlighting on match cases after multi-line case. Contributed by Olga Matoula.

.. date: 2025-07-19-10-35-31 .. gh-issue: 74185 .. nonce: 7hPCA5 .. section: Core and Builtins

The :meth:~object.__repr__ of :class:ImportError and :class:ModuleNotFoundError now shows "name" and "path" as name=<name> and path=<path> if they were given as keyword arguments at construction time. Patch by Serhiy Storchaka, Oleg Iarygin, and Yoav Nir

.. date: 2025-07-18-08-43-35 .. gh-issue: 116738 .. nonce: i0HWtP .. section: Library

Make functions in :mod:syslog thread-safe on the :term:free threaded <free threading> build.

.. date: 2025-07-15-10-03-57 .. gh-issue: 116738 .. nonce: oFttKl .. section: Library

Make functions in :mod:pwd thread-safe on the :term:free threaded <free threading> build.

.. date: 2025-07-14-17-01-23 .. gh-issue: 136616 .. nonce: FQjXE_ .. section: Core and Builtins

Improve :exc:SyntaxError error messages for invalid :keyword:assert usages.

.. date: 2025-07-13-21-21-17 .. gh-issue: 136599 .. nonce: sLhm2O .. section: Core and Builtins

Improve performance of :class:int hash calculations.

.. date: 2025-07-12-09-59-14 .. gh-issue: 136421 .. nonce: ZD1rNj .. section: Library

Fix crash when initializing :mod:datetime concurrently.

.. date: 2025-07-11-13-45-48 .. gh-issue: 136541 .. nonce: uZ_-Ju .. section: Core and Builtins

Fix some issues with the perf trampolines on x86-64 and aarch64. The trampolines were not being generated correctly for some cases, which could lead to the perf integration not working correctly. Patch by Pablo Galindo.

.. date: 2025-07-11-12-29-09 .. gh-issue: 107545 .. nonce: ipfl7U .. section: Library

Improve the error messages that may be raised by :meth:~socket.socket.setsockopt.

.. date: 2025-07-10-23-23-50 .. gh-issue: 136517 .. nonce: _NHJyv .. section: Core and Builtins

Fixed a typo that prevented printing of uncollectable objects when the :const:gc.DEBUG_UNCOLLECTABLE mode was set.

.. date: 2025-07-10-15-53-16 .. gh-issue: 136525 .. nonce: xAko0e .. section: Core and Builtins

Fix issue where per-thread bytecode was not instrumented for newly created threads.

.. date: 2025-07-09-21-27-14 .. gh-issue: 132657 .. nonce: kSA8R3 .. section: Core and Builtins

Improve performance of :class:frozenset by removing locks in the free-threading build.

.. date: 2025-07-09-11-15-42 .. gh-issue: 136459 .. nonce: m4Udh8 .. section: Core and Builtins

Add support for perf trampoline on macOS, to allow profilers wit JIT map support to read Python calls. While profiling, PYTHONPERFSUPPORT=1 can be appended to enable the trampoline.

.. date: 2025-07-08-23-53-51 .. gh-issue: 132661 .. nonce: B84iYt .. section: Core and Builtins

Interpolation.expression now has a default, the empty string.

.. date: 2025-07-08-23-22-08 .. gh-issue: 132661 .. nonce: 34ftJl .. section: Core and Builtins

Reflect recent :pep:750 change.

Disallow concatenation of string.templatelib.Template and :class:str. Also, disallow implicit concatenation of t-string literals with string or f-string literals.

.. date: 2025-07-07-17-26-06 .. gh-issue: 91636 .. nonce: GyHU72 .. section: Core and Builtins

While performing garbage collection, clear weakrefs to unreachable objects that are created during running of finalizers. If those weakrefs were are not cleared, they could reveal unreachable objects.

.. date: 2025-07-07-12-24-00 .. gh-issue: 136355 .. nonce: MTcA8j .. section: Core and Builtins

Deprecate :option:-b and :option:!-bb command line options and schedule them to become no-op in Python 3.17.

.. date: 2025-07-06-14-53-19 .. gh-issue: 109700 .. nonce: KVNQQi .. section: Core and Builtins

Fix memory error handling in :c:func:PyDict_SetDefault.

.. date: 2025-07-03-06-04-42 .. gh-issue: 135552 .. nonce: CbBQof .. section: Core and Builtins

Fix a bug caused by the garbage collector clearing weakrefs too early. The weakrefs in the tp_subclasses dictionary are needed in order to correctly invalidate type caches (for example, by calling PyType_Modified()). Clearing weakrefs before calling finalizers causes the caches to not be correctly invalidated. That can cause crashes since the caches can refer to invalid objects. Defer the clearing of weakrefs without callbacks until after finalizers are executed.

.. date: 2025-07-02-15-18-41 .. gh-issue: 136203 .. nonce: Y934sC .. section: Core and Builtins

Improve :exc:TypeError error message, when richcomparing two :class:types.MappingProxyType objects.

.. date: 2025-06-26-18-44-34 .. gh-issue: 136003 .. nonce: sln51d .. section: Core and Builtins

Fix :class:threading.Thread objects becoming incorrectly daemon when created from an :mod:atexit callback or a pending call (:c:func:Py_AddPendingCall).

.. date: 2025-06-26-15-25-51 .. gh-issue: 78465 .. nonce: MbDN8X .. section: Core and Builtins

Fix error message for cls.__new__(cls, ...) where cls is not instantiable builtin or extension type (with tp_new set to NULL).

.. date: 2025-06-24-16-46-34 .. gh-issue: 135904 .. nonce: 78xfon .. section: Core and Builtins

Perform more aggressive control-flow optimizations on the machine code templates emitted by the experimental JIT compiler.

.. date: 2025-06-24-06-41-47 .. gh-issue: 129958 .. nonce: EaJuS0 .. section: Core and Builtins

Differentiate between t-strings and f-strings in syntax error for newlines in format specifiers of single-quoted interpolated strings.

.. date: 2025-06-23-18-08-32 .. gh-issue: 135871 .. nonce: 50C528 .. section: Core and Builtins

Non-blocking mutex lock attempts now return immediately when the lock is busy instead of briefly spinning in the :term:free threading build.

.. date: 2025-06-20-14-50-44 .. gh-issue: 134584 .. nonce: 3CJdAI .. section: Core and Builtins

Specialize :opcode:POP_TOP in the JIT compiler by specializing for reference lifetime and type. This will also enable easier top of stack caching in the JIT compiler.

.. date: 2025-06-18-16-45-36 .. gh-issue: 135106 .. nonce: cpl6Aq .. section: Core and Builtins

Restrict the trashcan mechanism to GC'ed objects and untrack them while in the trashcan to prevent the GC and trashcan mechanisms conflicting.

.. date: 2025-06-18-12-19-13 .. gh-issue: 135379 .. nonce: TCvGpj .. section: Core and Builtins

Changes specialization of BINARY_OP for ints to only specialize for "compact" ints. This streamlines the fast path at the cost of fewer specializations when very large integers are used.

.. date: 2025-06-17-22-34-58 .. gh-issue: 135607 .. nonce: ucsLVu .. section: Core and Builtins

Fix potential :mod:weakref races in an object's destructor on the :term:free threaded <free threading> build.

.. date: 2025-06-17-12-50-48 .. gh-issue: 135608 .. nonce: PnHckD .. section: Core and Builtins

Fix a crash in the JIT involving attributes of modules.

.. date: 2025-06-17-08-37-45 .. gh-issue: 82088 .. nonce: TgPvLg .. section: Core and Builtins

Improve performance of PyLongObject conversion functions PyLong_AsLongAndOverflow(), PyLong_AsSsize_t(), PyLong_AsUnsignedLong(), PyLong_AsSize_t(), PyLong_AsUnsignedLongMask(), PyLong_AsUnsignedLongLongMask(), PyLong_AsLongLongAndOverflow() for integers larger than 2**30 up to 30%.

.. date: 2025-06-16-03-56-15 .. gh-issue: 135551 .. nonce: hRTQO- .. section: Core and Builtins

Sorting randomly ordered lists will often run a bit faster, thanks to a new scheme for picking minimum run lengths from Stefan Pochmann, which arranges for the merge tree to be as evenly balanced as is possible.

.. date: 2025-06-16-02-31-42 .. gh-issue: 135543 .. nonce: 6b0HOF .. section: Core and Builtins

Emit sys.remote_exec audit event when :func:sys.remote_exec is called and migrate remote_debugger_script to cpython.remote_debugger_script.

.. date: 2025-06-14-01-01-14 .. gh-issue: 135496 .. nonce: ER0Me3 .. section: Core and Builtins

Fix typo in the f-string conversion type error ("exclamanation" -> "exclamation").

.. date: 2025-06-13-16-05-24 .. gh-issue: 135474 .. nonce: 67nOl3 .. section: Core and Builtins

Specialize integer operations only on compact integers. This is a CPython internal change.

.. date: 2025-06-12-18-12-42 .. gh-issue: 135371 .. nonce: R_YUtR .. section: Core and Builtins

Fixed :mod:asyncio debugging tools to properly display internal coroutine call stacks alongside external task dependencies. The python -m asyncio ps and python -m asyncio pstree commands now show complete execution context. Patch by Pablo Galindo.

.. date: 2025-06-12-11-19-52 .. gh-issue: 135422 .. nonce: F6yQi6 .. section: Core and Builtins

Fix regression in :exc:SyntaxError messages after :gh:134036.

.. date: 2025-06-12-00-03-34 .. gh-issue: 116738 .. nonce: iBBAdo .. section: Library

Make functions in :mod:grp thread-safe on the :term:free threaded <free threading> build.

.. date: 2025-06-11-15-08-10 .. gh-issue: 127319 .. nonce: OVGFSZ .. section: Library

Set the allow_reuse_port class variable to False on the XMLRPC, logging, and HTTP servers. This matches the behavior in prior Python releases, which is to not allow port reuse.

.. date: 2025-06-09-23-57-37 .. gh-issue: 130077 .. nonce: MHknDB .. section: Core and Builtins

Properly raise custom syntax errors when incorrect syntax containing names that are prefixes of soft keywords is encountered. Patch by Pablo Galindo.

.. date: 2025-06-08-14-24-29 .. gh-issue: 131798 .. nonce: qfw91T .. section: Core and Builtins

Optimize _CALL_LEN in the JIT when the length is known. Patch by Tomas Roun

.. date: 2025-06-06-19-17-22 .. gh-issue: 131798 .. nonce: XoV8Eb .. section: Core and Builtins

Optimize _UNARY_NEGATIVE in JIT-compiled code.

.. date: 2025-06-06-02-24-42 .. gh-issue: 135148 .. nonce: r-t2sC .. section: Core and Builtins

Fixed a bug where f-string debug expressions (using =) would incorrectly strip out parts of strings containing escaped quotes and # characters. Patch by Pablo Galindo.

.. date: 2025-06-06-01-09-44 .. gh-issue: 131798 .. nonce: 1SuxO9 .. section: Core and Builtins

Optimize _UNARY_INVERT in JIT-compiled code.

.. date: 2025-06-05-21-58-30 .. gh-issue: 131798 .. nonce: nt5Ab7 .. section: Core and Builtins

Optimize away _CALL_TYPE_1 in the JIT when the return type is known. Patch by Tomas Roun

.. date: 2025-06-03-21-06-22 .. gh-issue: 133136 .. nonce: Usnvri .. section: Core and Builtins

Limit excess memory usage in the :term:free threading build when a large dictionary or list is resized and accessed by multiple threads.

.. date: 2025-06-02-20-13-37 .. gh-issue: 131798 .. nonce: JQRFvR .. section: Core and Builtins

Optimize _CHECK_METHOD_VERSION into _CHECK_FUNCTION_VERSION_INLINE in JIT-compiled code.

.. date: 2025-06-02-13-57-40 .. gh-issue: 116738 .. nonce: ycJsL8 .. section: Library

Make methods in :mod:heapq thread-safe on the :term:free threaded <free threading> build.

.. date: 2025-05-31-19-24-54 .. gh-issue: 134280 .. nonce: NDVbzY .. section: Core and Builtins

Disable constant folding for ~ with a boolean argument. This moves the deprecation warning from compile time to runtime.

.. date: 2025-05-31-10-26-46 .. gh-issue: 134876 .. nonce: 8mBGJI .. section: Core and Builtins

Add support to :pep:768 remote debugging for Linux kernels which don't have CONFIG_CROSS_MEMORY_ATTACH configured.

.. date: 2025-05-30-18-09-54 .. gh-issue: 134889 .. nonce: Ic9UM- .. section: Core and Builtins

Fix handling of a few opcodes that leave operands on the stack when optimizing LOAD_FAST.

.. date: 2025-05-30-15-56-19 .. gh-issue: 134908 .. nonce: 3a7PxM .. section: Library

Fix crash when iterating over lines in a text file on the :term:free threaded <free threading> build.

.. date: 2025-05-28-23-58-50 .. gh-issue: 117852 .. nonce: BO9g7z .. section: Core and Builtins

Fix argument checking of :meth:~agen.athrow.

.. date: 2025-05-27-20-29-00 .. gh-issue: 132617 .. nonce: EmUfQQ .. section: Core and Builtins

Fix :meth:dict.update modification check that could incorrectly raise a "dict mutated during update" error when a different dictionary was modified that happens to share the same underlying keys object.

.. date: 2025-05-27-20-21-34 .. gh-issue: 131798 .. nonce: b32zkl .. section: Core and Builtins

Allow the JIT to remove unnecessary _ITER_CHECK_TUPLE ops.

.. date: 2025-05-27-18-59-54 .. gh-issue: 134679 .. nonce: FWPBu6 .. section: Core and Builtins

Fix crash in the :term:free threading build's QSBR code that could occur when changing an object's __dict__ attribute.

.. date: 2025-05-26-15-55-50 .. gh-issue: 133912 .. nonce: -xAguL .. section: Core and Builtins

Fix the C API function PyObject_GenericSetDict to handle extension classes with inline values.

.. date: 2025-05-25-19-32-15 .. gh-issue: 131798 .. nonce: f5h8aI .. section: Core and Builtins

Make the JIT optimizer understand that slicing a string/list/tuple returns the same type.

.. date: 2025-05-23-14-54-07 .. gh-issue: 134584 .. nonce: y-WDjf .. section: Core and Builtins

Add a reference count elimination pass to the JIT compiler. Patch by Ken Jin.

.. date: 2025-05-22-17-49-39 .. gh-issue: 131798 .. nonce: U6ZmFm .. section: Core and Builtins

Optimize _POP_CALL_TWO_LOAD_CONST_INLINE_BORROW.

.. date: 2025-05-22-14-48-19 .. gh-issue: 134381 .. nonce: 2BXhth .. section: Library

Fix :exc:RuntimeError when using a not-started :class:threading.Thread after calling :func:os.fork

.. date: 2025-05-21-18-02-56 .. gh-issue: 127960 .. nonce: W3J_2X .. section: Core and Builtins

PyREPL interactive shell no longer starts with __package__ and __file__ global names set to _pyrepl package internals. Contributed by Yuichiro Tachibana.

.. date: 2025-05-21-15-14-32 .. gh-issue: 130397 .. nonce: aG6EON .. section: Core and Builtins

Remove special-casing for C stack depth limits for WASI. Due to WebAssembly's built-in stack protection this does not pose a security concern.

.. date: 2025-05-21-13-57-26 .. gh-issue: 131798 .. nonce: QwS5Bb .. section: Core and Builtins

JIT: replace _LOAD_SMALL_INT with _LOAD_CONST_INLINE_BORROW

.. date: 2025-05-20-23-32-11 .. gh-issue: 131798 .. nonce: G9ZQZw .. section: Core and Builtins

Improve the JIT's ability to optimize away cached class attribute and method loads.

.. date: 2025-05-20-14-41-50 .. gh-issue: 128066 .. nonce: qzzGfv .. section: Core and Builtins

Fixes an edge case where PyREPL improperly threw an error when Python is invoked on a read only filesystem while trying to write history file entries.

.. date: 2025-05-20-13-58-18 .. gh-issue: 131798 .. nonce: hG8xBw .. section: Core and Builtins

Improve the JIT's ability to narrow unknown classes to constant values.

.. date: 2025-05-19-20-52-53 .. gh-issue: 134268 .. nonce: HPKX1e .. section: Core and Builtins

Add _POP_CALL_TWO_LOAD_CONST_INLINE_BORROW and use it to further optimize CALL_ISINSTANCE.

.. date: 2025-05-19-15-15-58 .. gh-issue: 131798 .. nonce: PCP71j .. section: Core and Builtins

Split CALL_LIST_APPEND into several uops. Patch by Diego Russo.

.. date: 2025-05-18-14-33-23 .. gh-issue: 69605 .. nonce: ZMO49F .. section: Core and Builtins

When auto-completing an import in the :term:REPL, finding no candidates now issues no suggestion, rather than suggestions from the current namespace.

.. date: 2025-05-18-10-50-46 .. gh-issue: 134170 .. nonce: J0Hvmi .. section: Core and Builtins

Add colorization to :func:sys.unraisablehook by default.

.. date: 2025-05-17-20-56-05 .. gh-issue: 91153 .. nonce: afgtG2 .. section: Core and Builtins

Fix a crash when a :class:bytearray is concurrently mutated during item assignment.

.. date: 2025-05-17-20-44-51 .. gh-issue: 134158 .. nonce: ewLNLp .. section: Core and Builtins

Fix coloring of double braces in f-strings and t-strings in the :term:REPL.

.. date: 2025-05-16-20-59-12 .. gh-issue: 134119 .. nonce: w8expI .. section: Core and Builtins

Fix crash when calling :func:next on an exhausted template string iterator. Patch by Jelle Zijlstra.

.. date: 2025-05-16-17-25-52 .. gh-issue: 134100 .. nonce: 5-FbLK .. section: Core and Builtins

Fix a use-after-free bug that occurs when an imported module isn't in :data:sys.modules after its initial import. Patch by Nico-Posada.

.. date: 2025-05-16-09-06-38 .. gh-issue: 134036 .. nonce: st2e-B .. section: Core and Builtins

Improve :exc:SyntaxError message when using invalid :keyword:raise statements.

.. date: 2025-05-15-11-38-16 .. gh-issue: 133999 .. nonce: uBZ8uS .. section: Core and Builtins

Fix :exc:SyntaxError regression in :keyword:except parsing after :gh:123440.

.. date: 2025-05-11-13-40-42 .. gh-issue: 133886 .. nonce: ryBAyo .. section: Core and Builtins

Fix :func:sys.remote_exec for non-ASCII paths in non-UTF-8 locales and non-UTF-8 paths in UTF-8 locales.

.. date: 2025-05-11-09-40-19 .. gh-issue: 133400 .. nonce: zkWla8 .. section: Core and Builtins

Fixed Ctrl+D (^D) behavior in _pyrepl module to match old pre-3.13 REPL behavior.

.. date: 2025-05-10-17-12-27 .. gh-issue: 133703 .. nonce: bVM-re .. section: Core and Builtins

Fix hashtable in dict can be bigger than intended in some situations.

.. date: 2025-05-09-18-11-21 .. gh-issue: 133778 .. nonce: pWEV3t .. section: Core and Builtins

Fix bug where assigning to the :attr:~type.__annotations__ attributes of classes defined under from __future__ import annotations had no effect.

.. date: 2025-05-08-22-19-10 .. gh-issue: 133711 .. nonce: e91wUy .. section: Core and Builtins

Implement :pep:686: Enable :ref:Python UTF-8 Mode <utf8-mode> by default. Patch by Adam Turner.

.. date: 2025-05-08-13-48-02 .. gh-issue: 132762 .. nonce: tKbygC .. section: Core and Builtins

:meth:~dict.fromkeys no longer loops forever when adding a small set of keys to a large base dict. Patch by Angela Liss.

.. date: 2025-05-07-23-26-53 .. gh-issue: 133541 .. nonce: bHIC55 .. section: Core and Builtins

Inconsistent indentation in user input crashed the new REPL when syntax highlighting was active. This is now fixed.

.. date: 2025-05-06-15-01-41 .. gh-issue: 133516 .. nonce: RqWVf2 .. section: Core and Builtins

Raise :exc:ValueError when constants True, False or None are used as an identifier after NFKC normalization.

.. date: 2025-05-03-22-31-53 .. gh-issue: 131798 .. nonce: fQ0ato .. section: Core and Builtins

Allow the JIT to remove int guards after _GET_LEN by setting the return type to int.

.. date: 2025-05-03-13-36-01 .. gh-issue: 131798 .. nonce: U4_QEJ .. section: Core and Builtins

Split CALL_ISINSTANCE into several uops, allowing the JIT to remove some of them.

.. date: 2025-04-30-14-13-01 .. gh-issue: 132554 .. nonce: GqQaUp .. section: Core and Builtins

Change iteration to use "virtual iterators" for sequences. Instead of creating an iterator, a tagged integer representing the next index is pushed to the stack above the iterable. For non-sequence iterators, NULL is pushed.

.. date: 2025-04-28-18-59-11 .. gh-issue: 130821 .. nonce: B11LU1 .. section: Core and Builtins

Enhance wrong type error messages and make them more consistent. Patch by Semyon Moroz.

.. date: 2025-04-26-17-50-01 .. gh-issue: 131798 .. nonce: XiOgw5 .. section: Core and Builtins

Narrow the return type and constant-evaluate CALL_ISINSTANCE for a subset of known values in the JIT. Patch by Tomas Roun

.. date: 2025-04-19-17-16-46 .. gh-issue: 132542 .. nonce: 7T_TY_ .. section: Core and Builtins

Update :attr:Thread.native_id <threading.Thread.native_id> after :manpage:fork(2) to ensure accuracy. Patch by Noam Cohen.

.. date: 2025-04-19-16-22-47 .. gh-issue: 132732 .. nonce: jgqhlF .. section: Library

Automatically constant evaluate bytecode operations marked as pure in the JIT optimizer.

.. date: 2025-04-16-12-01-13 .. gh-issue: 127971 .. nonce: pMDOQ0 .. section: Core and Builtins

Fix off-by-one read beyond the end of a string in string search.

.. date: 2025-04-10-01-52-42 .. gh-issue: 132042 .. nonce: fePwlj .. section: Core and Builtins

Improve class creation times by up to 12% by pre-computing type slots just once. Patch by Sergey Miryanov.

.. date: 2025-04-04-16-41-00 .. gh-issue: 133379 .. nonce: asdjhjdf .. section: Core and Builtins

Correct usage of arguments in error messages.

.. date: 2025-03-14-13-08-20 .. gh-issue: 127266 .. nonce: _tyfBp .. section: Core and Builtins

In the free-threaded build, avoid data races caused by updating type slots or type flags after the type was initially created. For those (typically rare) cases, use the stop-the-world mechanism. Remove the use of atomics when reading or writing type flags. The use of atomics is not sufficient to avoid races (since flags are sometimes read without a lock and without atomics) and are no longer required.

.. date: 2025-02-22-01-23-23 .. gh-issue: 130425 .. nonce: x5SNQ8 .. section: Core and Builtins

Add "Did you mean: 'attr'?" suggestion when using del obj.attr if attr does not exist.

.. date: 2025-01-08-12-52-47 .. gh-issue: 128640 .. nonce: 9nbh9z .. section: Core and Builtins

Fix a crash when using threads inside of a subinterpreter.

.. date: 2024-06-04-20-26-21 .. gh-issue: 116738 .. nonce: q_hPYq .. section: Library

Make the module :mod:json safe to use under the free-threading build.

.. date: 2024-05-24-07-02-47 .. gh-issue: 119494 .. nonce: x3KUMC .. section: Core and Builtins

Exception text when trying to delete attributes of types was clarified.

.. date: 2025-10-10-20-59-07 .. gh-issue: 139924 .. nonce: ALByCb .. section: C API

Function watchers can now receive a PyFunction_PYFUNC_EVENT_MODIFY_QUALNAME event when a watched functions qualname is changed.

.. date: 2025-10-07-12-51-32 .. gh-issue: 111489 .. nonce: LCKKlg .. section: C API

Add :c:func:PyTuple_FromArray to create a :class:tuple from an array. Patch by Victor Stinner.

.. date: 2025-09-14-14-44-24 .. gh-issue: 136355 .. nonce: LCaYyC .. section: C API

Deprecate :c:member:PyConfig.bytes_warning field and schedule its removal in 3.17.

.. date: 2025-09-14-13-09-47 .. gh-issue: 138886 .. nonce: dlcTXL .. section: C API

Remove deprecated :c:func:!PySys_ResetWarnOptions C-API function.

.. date: 2025-09-12-13-05-20 .. gh-issue: 129813 .. nonce: dJZpME .. section: C API

Implement :pep:782, the :c:type:PyBytesWriter API. Add functions:

:c:func:PyBytesWriter_Create
:c:func:PyBytesWriter_Discard
:c:func:PyBytesWriter_FinishWithPointer
:c:func:PyBytesWriter_FinishWithSize
:c:func:PyBytesWriter_Finish
:c:func:PyBytesWriter_Format
:c:func:PyBytesWriter_GetData
:c:func:PyBytesWriter_GetSize
:c:func:PyBytesWriter_GrowAndUpdatePointer
:c:func:PyBytesWriter_Grow
:c:func:PyBytesWriter_Resize
:c:func:PyBytesWriter_WriteBytes

Patch by Victor Stinner.

.. date: 2025-08-19-15-31-36 .. gh-issue: 137956 .. nonce: P4TK1d .. section: C API

Display and raise an exception if an extension compiled for non-free-threaded Python is loaded in a free-threaded interpreter.

.. date: 2025-08-13-13-41-04 .. gh-issue: 137573 .. nonce: r6uwRf .. section: C API

Mark _PyOptimizer_Optimize as :c:macro:Py_NO_INLINE to prevent stack overflow crashes on macOS.

.. date: 2025-07-31-04-30-42 .. gh-issue: 128813 .. nonce: opL-Pv .. section: C API

Functions :c:func:_Py_c_sum, :c:func:_Py_c_diff, :c:func:_Py_c_neg, :c:func:_Py_c_prod, :c:func:_Py_c_quot, :c:func:_Py_c_pow and previously undocumented :c:func:_Py_c_abs are :term:soft deprecated. Deprecate also :c:member:~PyComplexObject.cval field of the :c:type:PyComplexObject type. Patch by Sergey B Kirpichev.

.. date: 2025-07-29-18-00-22 .. gh-issue: 137210 .. nonce: DD4VEm .. section: C API

Add API for checking an extension module's ABI compatibility: :c:data:Py_mod_abi, :c:func:PyABIInfo_Check, :c:macro:PyABIInfo_VAR and :c:data:Py_mod_abi.

.. date: 2025-07-23-22-30-23 .. gh-issue: 136759 .. nonce: ffB4wO .. section: C API

Rename lock.h to pylock.h to avoid potential include conflicts.

.. date: 2025-07-22-15-18-08 .. gh-issue: 112068 .. nonce: 4WvT-8 .. section: C API

Revert support of nullable arguments in :c:func:PyArg_Parse.

.. date: 2025-07-08-22-07-54 .. gh-issue: 136006 .. nonce: XRU5w4 .. section: C API

On Solaris, the :c:macro:!Py_NAN macro now expands to a :c:type:!double instead of a function address. Patch by Bénédikt Tran.

.. date: 2025-07-01-16-22-39 .. gh-issue: 135075 .. nonce: angu3J .. section: C API

Make :c:func:PyObject_SetAttr and :c:func:PyObject_SetAttrString fail if called with NULL value and an exception set. Patch by Victor Stinner.

.. date: 2025-06-25-01-03-10 .. gh-issue: 135906 .. nonce: UBrCWq .. section: C API

Fix compilation errors when compiling the internal headers with a C++ compiler.

.. date: 2025-06-24-11-10-01 .. gh-issue: 133296 .. nonce: lIEuVJ .. section: C API

New variants for the critical section API that accept one or two :c:type:PyMutex pointers rather than :c:type:PyObject instances are now public in the non-limited C API.

.. date: 2025-06-19-12-47-18 .. gh-issue: 133157 .. nonce: 1WA85f .. section: C API

Remove the private, undocumented macro :c:macro:!_Py_NO_SANITIZE_UNDEFINED.

.. date: 2025-06-05-11-06-07 .. gh-issue: 134989 .. nonce: 74p4ud .. section: C API

Fix Py_RETURN_NONE, Py_RETURN_TRUE and Py_RETURN_FALSE macros in the limited C API 3.11 and older: don't treat Py_None, Py_True and Py_False as immortal. Patch by Victor Stinner.

.. date: 2025-06-02-13-19-22 .. gh-issue: 134989 .. nonce: sDDyBN .. section: C API

Implement :c:func:PyObject_DelAttr and :c:func:PyObject_DelAttrString as macros in the limited C API 3.12 and older. Patch by Victor Stinner.

.. date: 2025-05-30-11-33-17 .. gh-issue: 134745 .. nonce: GN-zk2 .. section: C API

Change :c:func:!PyThread_allocate_lock implementation to PyMutex. On Windows, :c:func:!PyThread_acquire_lock_timed now supports the intr_flag parameter: it can be interrupted. Patch by Victor Stinner.

.. date: 2025-05-29-16-56-23 .. gh-issue: 134891 .. nonce: 7eKO8U .. section: C API

Add :c:type:PyUnstable_Unicode_GET_CACHED_HASH to get the cached hash of a string.

.. date: 2025-05-20-17-13-51 .. gh-issue: 134009 .. nonce: CpCmry .. section: C API

Expose :c:func:PyMutex_IsLocked as part of the public C API.

.. date: 2025-05-17-14-41-21 .. gh-issue: 134144 .. nonce: xVpZik .. section: C API

Fix crash when calling :c:func:Py_EndInterpreter with a :term:thread state that isn't the initial thread for the interpreter.

.. date: 2025-05-13-16-06-46 .. gh-issue: 133968 .. nonce: 6alWst .. section: C API

Add :c:func:PyUnicodeWriter_WriteASCII function to write an ASCII string into a :c:type:PyUnicodeWriter. The function is faster than :c:func:PyUnicodeWriter_WriteUTF8, but has an undefined behavior if the input string contains non-ASCII characters. Patch by Victor Stinner.

.. date: 2025-05-08-13-14-45 .. gh-issue: 133644 .. nonce: J8_KZ2 .. section: C API

Remove deprecated Python initialization getter functions Py_Get*. Patch by Bénédikt Tran.

.. date: 2025-05-08-12-40-59 .. gh-issue: 133644 .. nonce: FNexLJ .. section: C API

Remove deprecated function :c:func:!PyWeakref_GetObject and macro :c:macro:!PyWeakref_GET_OBJECT. Use :c:func:PyWeakref_GetRef instead. Patch by Bénédikt Tran.

.. date: 2025-05-08-12-25-47 .. gh-issue: 133644 .. nonce: Yb86Rm .. section: C API

Remove deprecated alias :c:func:!PyImport_ImportModuleNoBlock of :c:func:PyImport_ImportModule. Patch by Bénédikt Tran.

.. date: 2025-05-07-21-18-00 .. gh-issue: 133610 .. nonce: asdfjs .. section: C API

Remove deprecated functions :c:func:!PyUnicode_AsDecodedObject, :c:func:!PyUnicode_AsDecodedUnicode, :c:func:!PyUnicode_AsEncodedObject, and :c:func:!PyUnicode_AsEncodedUnicode.

.. date: 2025-04-17-12-37-27 .. gh-issue: 132629 .. nonce: 01ArwX .. section: C API

For unsigned integer formats in :c:func:PyArg_ParseTuple, accepting Python integers with value that is larger than the maximal value for the C type or less than the minimal value for the corresponding signed integer type of the same size is now deprecated.

.. date: 2025-04-14-07-41-28 .. gh-issue: 131185 .. nonce: ZCjMHD .. section: C API

:c:func:PyGILState_Ensure no longer crashes when called after interpreter finalization.

.. date: 2023-10-18-14-36-35 .. gh-issue: 108512 .. nonce: fMZLfr .. section: C API

Add functions :c:func:PySys_GetAttr, :c:func:PySys_GetAttrString, :c:func:PySys_GetOptionalAttr and :c:func:PySys_GetOptionalAttrString.

.. date: 2025-09-24-13-59-26 .. gh-issue: 138489 .. nonce: 1AcuZM .. section: Build

When cross-compiling for WASI by build_wasm or build_emscripten, the build-details.json step is now included in the build process, just like with native builds.

This fixes the libinstall task which requires the build-details.json file during the process.

.. date: 2025-09-04-12-16-31 .. gh-issue: 138497 .. nonce: Y_5YXh .. section: Build

The LLVM version used by the JIT at build time can now be modified using the LLVM_VERSION environment variable. Use this at your own risk, as there is only one officially supported LLVM version. For more information, please check Tools/jit/README.md.

.. date: 2025-08-27-11-32-02 .. gh-issue: 95952 .. nonce: KSymc7 .. section: Build

When cross-compiling for WASI, require that the HOSTRUNNER environment variable be explicitly set.

This was needed as macOS lacks the appropriate CLI tools to set a reasonable default.

.. date: 2025-08-27-09-52-45 .. gh-issue: 138061 .. nonce: fMVS9w .. section: Build

Ensure reproducible builds by making JIT stencil header generation deterministic.

.. date: 2025-08-26-21-18-32 .. gh-issue: 128042 .. nonce: 5voC8H .. section: Build

./configure now warns when --enable-optimizations and CFLAGS=-O0 are both set, suggesting removing -O0 from CFLAGS for optimal performance. Patch by Taegyun Kim.

.. date: 2025-08-13-12-10-12 .. gh-issue: 132339 .. nonce: 3Czz5y .. section: Build

Add support for OpenSSL 3.5.

.. date: 2025-07-18-17-15-00 .. gh-issue: 135621 .. nonce: 9cyCNb .. section: Build

PyREPL no longer depends on the :mod:curses standard library. Contributed by Łukasz Langa.

.. date: 2025-06-25-13-27-14 .. gh-issue: 135927 .. nonce: iCNPQc .. section: Build

Fix building with MSVC when passing option /std:clatest.

.. date: 2025-06-16-07-20-28 .. gh-issue: 119132 .. nonce: fcI8s7 .. section: Build

Remove "experimental" tag from the CPython free-threading build.

.. date: 2025-06-14-10-32-11 .. gh-issue: 135497 .. nonce: ajlV4F .. section: Build

Fix the detection of MAXLOGNAME in the configure.ac script.

.. date: 2025-05-30-11-02-30 .. gh-issue: 134923 .. nonce: gBkRg4 .. section: Build

Windows builds with profile-guided optimization enabled now use /GENPROFILE and /USEPROFILE instead of deprecated /LTCG: options.

.. date: 2025-05-24-16-59-20 .. gh-issue: 134632 .. nonce: i0W2hc .. section: Build

Fixed build-details.json generation to use INCLUDEPY, in order to reference the pythonX.Y subdirectory of the include directory, as required in :pep:739, instead of the top-level include directory.

.. date: 2025-05-21-22-13-30 .. gh-issue: 134486 .. nonce: yvdL6f .. section: Build

The :mod:ctypes module now performs a more portable test for the definition of :manpage:alloca(3), fixing a compilation failure on NetBSD.

.. date: 2025-05-21-19-46-28 .. gh-issue: 134455 .. nonce: vdwlrq .. section: Build

Fixed build-details.json generation to use the correct c_api.headers as defined in :pep:739, instead of c_api.include.

.. date: 2025-05-19-18-09-20 .. gh-issue: 134273 .. nonce: ZAliyy .. section: Build

Add support for configuring compiler flags for the JIT with CFLAGS_JIT

.. date: 2025-05-16-07-46-06 .. gh-issue: 115119 .. nonce: ALBgS_ .. section: Build

Removed implicit fallback to the bundled copy of the libmpdec library. Now this should be explicitly enabled via :option:--with-system-libmpdec set to no or :option:!--without-system-libmpdec. Patch by Sergey B Kirpichev.

.. date: 2025-05-14-09-43-48 .. gh-issue: 131769 .. nonce: H0oy5x .. section: Build

Fix detecting when the build Python in a cross-build is a pydebug build.

.. date: 2025-04-16-09-38-48 .. gh-issue: 117088 .. nonce: EFt_5c .. section: Build

AIX linker don't support -h option, so avoid it through platform check

.. date: 2025-01-03-13-02-06 .. gh-issue: 123681 .. nonce: gQ67nK .. section: Build

Check the strftime() behavior at runtime instead of at the compile time to support cross-compiling. Remove the internal macro _Py_NORMALIZE_CENTURY.

.. date: 2024-12-04-10-00-35 .. gh-issue: 127545 .. nonce: t0THjE .. section: Build

Fix crash when building on Linux/m68k.