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gh-87135: threading.Lock: Raise rather than hang on Python finalization #135991

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Merged
merged 6 commits into from
Jul 1, 2025
Merged

gh-87135: threading.Lock: Raise rather than hang on Python finalization #135991

merged 6 commits into from
Jul 1, 2025
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encukou
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@encukou encukou commented Jun 26, 2025 •
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After Python finalization gets to the point where no other thread can attach thread state, attempting to acquire a Python lock will hang.
Raise PythonFinalizationError instead of hanging.

@colesbury, does this look maintainable (and correct) to you?

@encukou
pythongh-87135: threading.Lock: Raise rather than hang on Python fina…
42ba6e7 
…lization

After Python finalization gets to the point where no other thread
can attach thread state, attempting to acquire a Python lock must
hang.
Raise PythonFinalizationError instead of hanging.
@encukou encukou requested a review from colesbury June 26, 2025 14:46
@bedevere-app bedevere-app bot mentioned this pull request Jun 26, 2025
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colesbury
colesbury reviewed Jun 26, 2025
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I think this approach makes sense. A comment about the flags below

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Tests / Windows (free-threading) / Build and test (arm64) (pull_request)
Tests / Windows (free-threading) / Build and test (x64) (pull_request)

There is a suspicious error when running test.test_multiprocessing_spawn.test_processes:

Assertion failed: !PyErr_Occurred(), file D:\a\cpython\cpython\Python\specialize.c, line 740
Fatal Python error: Aborted

<Cannot show all threads while the GIL is disabled>
Stack (most recent call first):
  File "D:\a\cpython\cpython\Lib\logging\__init__.py", line 891 in _removeHandlerRef

Current thread's C stack trace (most recent call first):
  <cannot get C stack on this system>

vstinner
vstinner approved these changes Jun 27, 2025
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LGTM

@encukou encukou merged commit fe119a0 into python:main Jul 1, 2025
44 checks passed
@github-project-automation github-project-automation bot moved this from Todo to Done in MEDX-arabic-programme Jul 1, 2025
@encukou encukou deleted the no-acquire-in-finalize branch July 1, 2025 08:57
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@vstinner vstinner vstinner approved these changes

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