https://github.com/python/cpython/commit/1f5e23fd7015a8f7b14d0181ec83efa95c5d5b68 commit: 1f5e23fd7015a8f7b14d0181ec83efa95c5d5b68 branch: main author: Neil Schemenauer <nas-git...@arctrix.com> committer: nascheme <nas-git...@arctrix.com> date: 2025-06-25T20:03:24-07:00 summary:
Add whatsnew text for warnings module changes. (gh-135869) files: M Doc/whatsnew/3.14.rst diff --git a/Doc/whatsnew/3.14.rst b/Doc/whatsnew/3.14.rst index cbca720b75e96c..a74d414ae4bb70 100644 --- a/Doc/whatsnew/3.14.rst +++ b/Doc/whatsnew/3.14.rst @@ -978,6 +978,23 @@ be specified by the build backend, as it will no longer be determined automatically by the C compiler. For a running interpreter, the setting that was used at compile time can be found using :func:`sysconfig.get_config_var`. +A new flag has been added, :data:`~sys.flags.context_aware_warnings`. This +flag defaults to true for the free-threaded build and false for the GIL-enabled +build. If the flag is true then the :class:`warnings.catch_warnings` context +manager uses a context variable for warning filters. This makes the context +manager behave predicably when used with multiple threads or asynchronous +tasks. + +A new flag has been added, :data:`~sys.flags.thread_inherit_context`. This flag +defaults to true for the free-threaded build and false for the GIL-enabled +build. If the flag is true then threads created with :class:`threading.Thread` +start with a copy of the :class:`~contextvars.Context()` of the caller of +:meth:`~threading.Thread.start`. Most significantly, this makes the warning +filtering context established by :class:`~warnings.catch_warnings` be +"inherited" by threads (or asyncio tasks) started within that context. It also +affects other modules that use context variables, such as the :mod:`decimal` +context manager. + .. _whatsnew314-pyrepl-highlighting: @@ -1028,6 +1045,18 @@ Please report any bugs or major performance regressions that you encounter! .. seealso:: :pep:`744` +Concurrent safe warnings control +-------------------------------- + +The :class:`warnings.catch_warnings` context manager will now optionally +use a context variable for warning filters. This is enabled by setting +the :data:`~sys.flags.context_aware_warnings` flag, either with the ``-X`` +command-line option or an environment variable. This gives predicable +warnings control when using :class:`~warnings.catch_warnings` combined with +multiple threads or asynchronous tasks. The flag defaults to true for the +free-threaded build and false for the GIL-enabled build. + +(Contributed by Neil Schemenauer and Kumar Aditya in :gh:`130010`.) Other language changes ====================== _______________________________________________ Python-checkins mailing list -- python-checkins@python.org To unsubscribe send an email to python-checkins-le...@python.org https://mail.python.org/mailman3//lists/python-checkins.python.org Member address: arch...@mail-archive.com
