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bpo-39511: PyThreadState_Clear() calls on_delete (GH-18296) 

PyThreadState.on_delete is a callback used to notify Python when a
thread completes. _thread._set_sentinel() function creates a lock
which is released when the thread completes. It sets on_delete
callback to the internal release_sentinel() function. This lock is
known as Threading._tstate_lock in the threading module.

The release_sentinel() function uses the Python C API. The problem is
that on_delete is called late in the Python finalization, when the C
API is no longer fully working.

The PyThreadState_Clear() function now calls the
PyThreadState.on_delete callback. Previously, that happened in
PyThreadState_Delete().

The release_sentinel() function is now called when the C API is still
fully working.
This commit is contained in:
Victor Stinner 2020-02-01 02:30:25 +01:00 committed by GitHub
parent 7dc140126e
commit 4d96b4635a
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3 changed files with 12 additions and 3 deletions
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4
Doc/c-api/init.rst
View File

@ -1048,6 +1048,10 @@ All of the following functions must be called after :c:func:`Py_Initialize`.
Reset all information in a thread state object. The global interpreter lock
must be held.
.. versionchanged:: 3.9
This function now calls the :c:member:`PyThreadState.on_delete` callback.
Previously, that happened in :c:func:`PyThreadState_Delete`.
.. c:function:: void PyThreadState_Delete(PyThreadState *tstate)

3
Misc/NEWS.d/next/C API/2020-01-31-16-35-21.bpo-39511.nv9yEn.rst Normal file
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@ -0,0 +1,3 @@
The :c:func:`PyThreadState_Clear` function now calls the
:c:member:`PyThreadState.on_delete` callback. Previously, that happened in
:c:func:`PyThreadState_Delete`.

8
Python/pystate.c
View File

@ -806,6 +806,10 @@ PyThreadState_Clear(PyThreadState *tstate)
Py_CLEAR(tstate->async_gen_finalizer);
Py_CLEAR(tstate->context);
if (tstate->on_delete != NULL) {
tstate->on_delete(tstate->on_delete_data);
}
}
@ -830,9 +834,7 @@ tstate_delete_common(PyThreadState *tstate,
if (tstate->next)
tstate->next->prev = tstate->prev;
HEAD_UNLOCK(runtime);
if (tstate->on_delete != NULL) {
tstate->on_delete(tstate->on_delete_data);
}
PyMem_RawFree(tstate);
if (gilstate->autoInterpreterState &&