90fe3250f8
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`.
66 lines
1.6 KiB
C
66 lines
1.6 KiB
C
// The _PySemaphore API a simplified cross-platform semaphore used to implement
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// wakeup/sleep.
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#ifndef Py_INTERNAL_SEMAPHORE_H
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#define Py_INTERNAL_SEMAPHORE_H
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#ifndef Py_BUILD_CORE
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# error "this header requires Py_BUILD_CORE define"
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#endif
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#include "pycore_pythread.h" // _POSIX_SEMAPHORES
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#ifdef MS_WINDOWS
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# ifndef WIN32_LEAN_AND_MEAN
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# define WIN32_LEAN_AND_MEAN
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# endif
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# include <windows.h>
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#elif defined(HAVE_PTHREAD_H)
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# include <pthread.h>
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#elif defined(HAVE_PTHREAD_STUBS)
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# include "cpython/pthread_stubs.h"
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#else
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# error "Require native threads. See https://bugs.python.org/issue31370"
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#endif
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#if (defined(_POSIX_SEMAPHORES) && (_POSIX_SEMAPHORES+0) != -1 && \
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defined(HAVE_SEM_TIMEDWAIT))
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# define _Py_USE_SEMAPHORES
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# include <semaphore.h>
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#endif
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#ifdef __cplusplus
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extern "C" {
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#endif
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typedef struct _PySemaphore {
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#if defined(MS_WINDOWS)
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HANDLE platform_sem;
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#elif defined(_Py_USE_SEMAPHORES)
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sem_t platform_sem;
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#else
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pthread_mutex_t mutex;
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pthread_cond_t cond;
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int counter;
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#endif
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} _PySemaphore;
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// Puts the current thread to sleep until _PySemaphore_Wakeup() is called.
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PyAPI_FUNC(int)
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_PySemaphore_Wait(_PySemaphore *sema, PyTime_t timeout_ns);
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// Wakes up a single thread waiting on sema. Note that _PySemaphore_Wakeup()
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// can be called before _PySemaphore_Wait().
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PyAPI_FUNC(void)
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_PySemaphore_Wakeup(_PySemaphore *sema);
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// Initializes/destroys a semaphore
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PyAPI_FUNC(void) _PySemaphore_Init(_PySemaphore *sema);
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PyAPI_FUNC(void) _PySemaphore_Destroy(_PySemaphore *sema);
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#ifdef __cplusplus
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}
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#endif
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#endif /* !Py_INTERNAL_SEMAPHORE_H */
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