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Deletion of autoTSSkey during runtime finalization is not safe #131185

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Deletion of autoTSSkey during runtime finalization is not safe#131185
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interpreter-core(Objects, Python, Grammar, and Parser dirs)type-bugAn unexpected behavior, bug, or error
@colesbury

Description

@colesbury
colesbury
opened on Mar 13, 2025

Bug report

The autoTssKey is deleted during _PyRuntimeState_Fini by gilstate_tss_fini. This isn't safe because other threads may try calling PyGILState_Ensure() or PyGILState_GetThisThreadState() concurrently during shutdown.

cpython/Python/pystate.c

Lines 486 to 501 in e9d210b

void
_PyRuntimeState_Fini(_PyRuntimeState *runtime)
{
#ifdef Py_REF_DEBUG
/* The count is cleared by _Py_FinalizeRefTotal(). */
assert(runtime->object_state.interpreter_leaks == 0);
#endif
if (gilstate_tss_initialized(runtime)) {
gilstate_tss_fini(runtime);
}
if (PyThread_tss_is_created(&runtime->trashTSSkey)) {
PyThread_tss_delete(&runtime->trashTSSkey);
}
}

We can:

  1. Convert autoTssKey to a _Py_thread_local like _Py_tss_tstate, which doesn't require deletion
  2. Don't delete autoTssKey at runtime finalization

My preference is for the first option.

cc @ZeroIntensity @ericsnowcurrently @gpshead

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    interpreter-core(Objects, Python, Grammar, and Parser dirs)type-bugAn unexpected behavior, bug, or error

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