bpo-39877: Refactor take_gil() function (GH-18885)
* Remove ceval parameter of take_gil(): get it from tstate. * Move exit_thread_if_finalizing() call inside take_gil(). Replace exit_thread_if_finalizing() with tstate_must_exit(): the caller is now responsible to call PyThread_exit_thread(). * Move is_tstate_valid() assertion inside take_gil(). Remove is_tstate_valid(): inline code into take_gil(). * Move gil_created() assertion inside take_gil().
This commit is contained in:
Victor Stinner
GitHub
parent
363fab83b8
commit
85f5a69ae1
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@ -198,16 +198,6 @@ ensure_tstate_not_null(const char *func, PyThreadState *tstate)
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}
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#ifndef NDEBUG
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static int is_tstate_valid(PyThreadState *tstate)
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{
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assert(!_PyMem_IsPtrFreed(tstate));
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assert(!_PyMem_IsPtrFreed(tstate->interp));
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return 1;
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}
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#endif
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int
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PyEval_ThreadsInitialized(void)
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{
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@ -230,13 +220,15 @@ _PyEval_InitThreads(PyThreadState *tstate)
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PyThread_init_thread();
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create_gil(gil);
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take_gil(ceval, tstate);
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take_gil(tstate);
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struct _pending_calls *pending = &ceval->pending;
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pending->lock = PyThread_allocate_lock();
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if (pending->lock == NULL) {
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return _PyStatus_NO_MEMORY();
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}
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return _PyStatus_OK();
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}
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@ -269,30 +261,6 @@ _PyEval_FiniThreads(struct _ceval_runtime_state *ceval)
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}
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}
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/* This function is designed to exit daemon threads immediately rather than
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taking the GIL if Py_Finalize() has been called.
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The caller must *not* hold the GIL, since this function does not release
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the GIL before exiting the thread.
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When this function is called by a daemon thread after Py_Finalize() has been
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called, the GIL does no longer exist.
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tstate must be non-NULL. */
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static inline void
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exit_thread_if_finalizing(PyThreadState *tstate)
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{
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/* bpo-39877: Access _PyRuntime directly rather than using
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tstate->interp->runtime to support calls from Python daemon threads.
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After Py_Finalize() has been called, tstate can be a dangling pointer:
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point to PyThreadState freed memory. */
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_PyRuntimeState *runtime = &_PyRuntime;
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PyThreadState *finalizing = _PyRuntimeState_GetFinalizing(runtime);
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if (finalizing != NULL && finalizing != tstate) {
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PyThread_exit_thread();
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}
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}
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void
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_PyEval_Fini(void)
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{
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@ -329,11 +297,7 @@ PyEval_AcquireLock(void)
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PyThreadState *tstate = _PyRuntimeState_GetThreadState(runtime);
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ensure_tstate_not_null(__func__, tstate);
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exit_thread_if_finalizing(tstate);
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assert(is_tstate_valid(tstate));
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struct _ceval_runtime_state *ceval = &runtime->ceval;
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take_gil(ceval, tstate);
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take_gil(tstate);
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}
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void
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@ -353,17 +317,10 @@ PyEval_AcquireThread(PyThreadState *tstate)
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{
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ensure_tstate_not_null(__func__, tstate);
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exit_thread_if_finalizing(tstate);
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assert(is_tstate_valid(tstate));
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take_gil(tstate);
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_PyRuntimeState *runtime = tstate->interp->runtime;
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struct _ceval_runtime_state *ceval = &runtime->ceval;
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/* Check that _PyEval_InitThreads() was called to create the lock */
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assert(gil_created(&ceval->gil));
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take_gil(ceval, tstate);
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if (_PyThreadState_Swap(&runtime->gilstate, tstate) != NULL) {
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struct _gilstate_runtime_state *gilstate = &tstate->interp->runtime->gilstate;
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if (_PyThreadState_Swap(gilstate, tstate) != NULL) {
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Py_FatalError("non-NULL old thread state");
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}
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}
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@ -396,7 +353,8 @@ _PyEval_ReInitThreads(_PyRuntimeState *runtime)
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recreate_gil(&ceval->gil);
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PyThreadState *tstate = _PyRuntimeState_GetThreadState(runtime);
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ensure_tstate_not_null(__func__, tstate);
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take_gil(ceval, tstate);
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take_gil(tstate);
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struct _pending_calls *pending = &ceval->pending;
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pending->lock = PyThread_allocate_lock();
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@ -436,16 +394,10 @@ PyEval_RestoreThread(PyThreadState *tstate)
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{
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ensure_tstate_not_null(__func__, tstate);
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exit_thread_if_finalizing(tstate);
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assert(is_tstate_valid(tstate));
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take_gil(tstate);
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_PyRuntimeState *runtime = tstate->interp->runtime;
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struct _ceval_runtime_state *ceval = &runtime->ceval;
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assert(gil_created(&ceval->gil));
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take_gil(ceval, tstate);
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_PyThreadState_Swap(&runtime->gilstate, tstate);
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struct _gilstate_runtime_state *gilstate = &tstate->interp->runtime->gilstate;
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_PyThreadState_Swap(gilstate, tstate);
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}
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@ -805,7 +757,6 @@ _PyEval_EvalFrameDefault(PyFrameObject *f, int throwflag)
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PyThreadState * const tstate = _PyRuntimeState_GetThreadState(runtime);
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ensure_tstate_not_null(__func__, tstate);
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assert(is_tstate_valid(tstate));
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/* when tracing we set things up so that
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@ -1294,10 +1245,7 @@ main_loop:
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/* Other threads may run now */
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/* Check if we should make a quick exit. */
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exit_thread_if_finalizing(tstate);
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take_gil(ceval, tstate);
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take_gil(tstate);
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if (_PyThreadState_Swap(&runtime->gilstate, tstate) != NULL) {
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Py_FatalError("orphan tstate");
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@ -180,17 +180,55 @@ drop_gil(struct _ceval_runtime_state *ceval, PyThreadState *tstate)
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#endif
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}
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/* Check if a Python thread must exit immediately, rather than taking the GIL
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if Py_Finalize() has been called.
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When this function is called by a daemon thread after Py_Finalize() has been
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called, the GIL does no longer exist.
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tstate must be non-NULL. */
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static inline int
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tstate_must_exit(PyThreadState *tstate)
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{
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/* bpo-39877: Access _PyRuntime directly rather than using
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tstate->interp->runtime to support calls from Python daemon threads.
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After Py_Finalize() has been called, tstate can be a dangling pointer:
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point to PyThreadState freed memory. */
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_PyRuntimeState *runtime = &_PyRuntime;
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PyThreadState *finalizing = _PyRuntimeState_GetFinalizing(runtime);
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return (finalizing != NULL && finalizing != tstate);
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}
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/* Take the GIL.
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The function saves errno at entry and restores its value at exit.
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tstate must be non-NULL. */
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static void
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take_gil(struct _ceval_runtime_state *ceval, PyThreadState *tstate)
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take_gil(PyThreadState *tstate)
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{
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int err = errno;
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assert(tstate != NULL);
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/* Check if we should make a quick exit. */
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if (tstate_must_exit(tstate)) {
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PyThread_exit_thread();
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}
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/* Ensure that tstate is valid: sanity check for PyEval_AcquireThread() and
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PyEval_RestoreThread(). Detect if tstate memory was freed. */
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assert(!_PyMem_IsPtrFreed(tstate));
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assert(!_PyMem_IsPtrFreed(tstate->interp));
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struct _ceval_runtime_state *ceval = &tstate->interp->runtime->ceval;
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struct _gil_runtime_state *gil = &ceval->gil;
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/* Check that _PyEval_InitThreads() was called to create the lock */
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assert(gil_created(gil));
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MUTEX_LOCK(gil->mutex);
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if (!_Py_atomic_load_relaxed(&gil->locked)) {
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@ -215,6 +253,7 @@ take_gil(struct _ceval_runtime_state *ceval, PyThreadState *tstate)
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SET_GIL_DROP_REQUEST(ceval);
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}
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}
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_ready:
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#ifdef FORCE_SWITCHING
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/* This mutex must be taken before modifying gil->last_holder:
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