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_Py_IsFinalizing has been removed, meaning C/C++ threads cannot avoid termination during shutdown #108014
Description
Checklist
- I am confident this is a bug in CPython, not a bug in a third-party project
- I have searched the CPython issue tracker,
and am confident this bug has not been reported before
CPython versions tested on:
CPython main branch
Operating systems tested on:
Linux
Output from running 'python -VV' on the command line:
Python 3.13.0a0 (main, Jul 29 2023, 00:25:05) [GCC 13.1.1 20230614 (Red Hat 13.1.1-4)]
A clear and concise description of the bug:
Threads that call PyEval_RestoreThread while the runtime is finalizing are terminated. The documented way to avoid this is to call _Py_IsFinalizing() to check. https://docs.python.org/3.13/c-api/init.html#c.PyEval_RestoreThread
_Py_IsFinalizing() has been removed from Python 3.13. Please provide a public API function that has the equivalent behavior, or some other way for a non-Python thread to safely attempt to call into Python code when the interpreter may be finalizing.
Rather than the calling code checking for finalization, an alternative solution would be to provide a variant of PyEval_RestoreThread that returns success or failure, so the calling code can know that it was unable to acquire the GIL, and react accordingly.
Activity
vstinner commentedon Aug 16, 2023
Since
sys.is_finalizing()was added to Python 3.5, IMO it's fine to add a public C API function for that: https://docs.python.org/dev/library/sys.html#sys.is_finalizingcc @ericsnowcurrently
pythongh-108014: Add Py_IsFinalizing() function
ericsnowcurrently commentedon Aug 16, 2023
FYI, there is some work to hang remaining threads rather than killing them: gh-105805. I expect that would land in 3.13.
Presumably a
Py_IsFinalizing()would still be helpful though.erlend-aasland commentedon Aug 17, 2023
I think it would make sense to also make
_Py_IsInterpreterFinalizingpublic:cpython/Python/pylifecycle.c
Lines 2181 to 2191 in 1344cfa
gh-108014: Add Py_IsFinalizing() function (#108032)
vstinner commentedon Aug 18, 2023
Function added by commit 3ff5ef2.
vstinner commentedon Aug 18, 2023
Function added to pythoncapi-compat by commit python/pythoncapi-compat@1bb4e16.
vstinner commentedon Sep 25, 2023
I proposed adding PythonFinalizationError exception in PR gh-109809.
vstinner commentedon Oct 5, 2023
Follow-up: @wjakob asks to add this new function to the limited C API version 3.13.