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[3.9] GH-102126: fix deadlock at shutdown when clearing thread states (GH-102222) #102236

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Merged
merged 1 commit into from
Mar 28, 2023
Merged

[3.9] GH-102126: fix deadlock at shutdown when clearing thread states (GH-102222) #102236

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1 change: 1 addition & 0 deletions Misc/NEWS.d/next/Core and Builtins/2023-02-24-17-59-39.gh-issue-102126.HTT8Vc.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
Fix deadlock at shutdown when clearing thread states if any finalizer tries to acquire the runtime head lock. Patch by Kumar Aditya.
12 changes: 10 additions & 2 deletions Python/pystate.c
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Expand Up @@ -288,11 +288,19 @@ PyInterpreterState_Clear(PyInterpreterState *interp)
_PyErr_Clear(tstate);
}

// Clear the current/main thread state last.
HEAD_LOCK(runtime);
for (PyThreadState *p = interp->tstate_head; p != NULL; p = p->next) {
PyThreadState *p = interp->tstate_head;
HEAD_UNLOCK(runtime);
while (p != NULL) {
// See https://github.com/python/cpython/issues/102126
// Must be called without HEAD_LOCK held as it can deadlock
// if any finalizer tries to acquire that lock.
PyThreadState_Clear(p);
HEAD_LOCK(runtime);
p = p->next;
HEAD_UNLOCK(runtime);
}
HEAD_UNLOCK(runtime);

Py_CLEAR(interp->audit_hooks);

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