gh-138813: Fix mutable default kwargs={} in multiprocessing BaseProcess and DummyProcess to use None#138814
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gpshead merged 4 commits intopython:mainfrom Sep 17, 2025
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The core change looks good to me, but please add a test case to test_multiprocessing.
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@ZeroIntensity, I’ve addressed your comment, please take another look. |
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Misc/NEWS.d/next/Library/2025-09-13-15-31-09.gh-issue-138813.1k7qT6.rst
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Did the test case disappear?
Misc/NEWS.d/next/Library/2025-09-15-07-02-26.gh-issue-138813.yIju93.rst
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Added the test in the latest commit. |
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needs backport to 3.13
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…eProcess and DummyProcess to use None (pythonGH-138814) * pythongh-138813: Default `BaseProcess` `kwargs` to `None` (pythonGH-138814) Set `BaseProcess.__init__(..., kwargs=None)` and initialize `kwargs` with `dict(kwargs) if kwargs else {}`. This avoids a shared mutable default and matches threading.Thread behavior. Co-authored-by: Dmitrii Chuprov <cheese@altlinux.org> * DummyProcess kwargs=None (which threading.Thread accepts properly) (cherry picked from commit 5a15e73) Co-authored-by: Denis Sergeev <newjimbatler00@gmail.com> Co-authored-by: Gregory P. Smith <greg@krypto.org>
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…eProcess and DummyProcess to use None (pythonGH-138814) * pythongh-138813: Default `BaseProcess` `kwargs` to `None` (pythonGH-138814) Set `BaseProcess.__init__(..., kwargs=None)` and initialize `kwargs` with `dict(kwargs) if kwargs else {}`. This avoids a shared mutable default and matches threading.Thread behavior. Co-authored-by: Dmitrii Chuprov <cheese@altlinux.org> * DummyProcess kwargs=None (which threading.Thread accepts properly) (cherry picked from commit 5a15e73) Co-authored-by: Denis Sergeev <newjimbatler00@gmail.com> Co-authored-by: Gregory P. Smith <greg@krypto.org>
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GH-139083 is a backport of this pull request to the 3.13 branch. |
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GH-139084 is a backport of this pull request to the 3.14 branch. |
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…seProcess and DummyProcess to use None (GH-138814) (#139084) gh-138813: Fix mutable default kwargs={} in multiprocessing BaseProcess and DummyProcess to use None (GH-138814) * gh-138813: Default `BaseProcess` `kwargs` to `None` (GH-138814) Set `BaseProcess.__init__(..., kwargs=None)` and initialize `kwargs` with `dict(kwargs) if kwargs else {}`. This avoids a shared mutable default and matches threading.Thread behavior. * DummyProcess kwargs=None (which threading.Thread accepts properly) (cherry picked from commit 5a15e73) Co-authored-by: Denis Sergeev <newjimbatler00@gmail.com> Co-authored-by: Gregory P. Smith <greg@krypto.org> Co-authored-by: Petr Viktorin <encukou@gmail.com> Co-authored-by: Gregory P. Smith <68491+gpshead@users.noreply.github.com>
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Change the default value of the 'kwargs' parameter in DummyProcess.init() from {} to None to avoid mutable default argument issues. This makes DummyProcess consistent with threading.Thread and threading.Timer which already use this pattern.
Found by Linux Verification Center (linuxtesting.org) with SVACE.
Reported by: Dmitrii Chuprov cheese@altlinux.org
multiprocessing.dummy.DummyProcess.__init__#138813