gh-138813: Fix mutable default kwargs={} in multiprocessing BaseProcess and DummyProcess to use None #138814
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The core change looks good to me, but please add a test case to test_multiprocessing.
gpshead
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Most changes to Python require a NEWS entry. Add one using the blurb_it web app or the blurb command-line tool. If this change has little impact on Python users, wait for a maintainer to apply the |
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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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) 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 <[email protected]>
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) 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 <[email protected]>
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Most changes to Python require a NEWS entry. Add one using the blurb_it web app or the blurb command-line tool. If this change has little impact on Python users, wait for a maintainer to apply the |
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 <[email protected]> * DummyProcess kwargs=None (which threading.Thread accepts properly) (cherry picked from commit 5a15e73) Co-authored-by: Denis Sergeev <[email protected]> Co-authored-by: Gregory P. Smith <[email protected]>
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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 <[email protected]> * DummyProcess kwargs=None (which threading.Thread accepts properly) (cherry picked from commit 5a15e73) Co-authored-by: Denis Sergeev <[email protected]> Co-authored-by: Gregory P. Smith <[email protected]>
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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 <[email protected]> Co-authored-by: Gregory P. Smith <[email protected]> Co-authored-by: Petr Viktorin <[email protected]> Co-authored-by: Gregory P. Smith <[email protected]>
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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 [email protected]
multiprocessing.dummy.DummyProcess.__init__#138813