gh-137433: Fix deadlock with stop-the-world and daemon threads #137735
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There was a deadlock originally seen by Memray when a daemon thread enabled or disabled profiling while the interpreter was shutting down. I think this could also happen with garbage collection, but I haven't seen that in practice. The daemon thread could be hung while trying acquire the global rwmutex that prevents overlapping global and per-interpreter stop-the-world events. Since it already held the main interpreter's stop-the-world lock, it also deadlocked the main thread, which is trying to perform interpreter finalization. Swap the order of lock acquisition to prevent this deadlock. Additionally, refactor `_PyParkingLot_Park` so that the global buckets hashtable is left in a clean state if the thread is hung in `PyEval_AcquireThread`.
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There was a deadlock originally seen by Memray when a daemon thread enabled or disabled profiling while the interpreter was shutting down. I think this could also happen with garbage collection, but I haven't seen that in practice.
The daemon thread could be hung while trying acquire the global rwmutex that prevents overlapping global and per-interpreter stop-the-world events. Since it already held the main interpreter's stop-the-world lock, it also deadlocked the main thread, which is trying to perform interpreter finalization.
Swap the order of lock acquisition to prevent this deadlock. Additionally, refactor
_PyParkingLot_Parkso that the global buckets hashtable is left in a clean state if the thread is hung inPyEval_AcquireThread.