[2.7] bpo-20891: Fix PyGILState_Ensure() (#4650) by vstinner · Pull Request #4657 · python/cpython

python

@@ -588,6 +588,8 @@ PyGILState_Ensure(void) { int current; PyThreadState *tcur; int need_init_threads = 0;
/* Note that we do not auto-init Python here - apart from potential races with 2 threads auto-initializing, pep-311 spells out other issues. Embedders are expected to have @@ -596,6 +598,8 @@ PyGILState_Ensure(void) assert(autoInterpreterState); /* Py_Initialize() hasn't been called! */ tcur = (PyThreadState *)PyThread_get_key_value(autoTLSkey); if (tcur == NULL) { need_init_threads = 1;
/* Create a new thread state for this thread */ tcur = PyThreadState_New(autoInterpreterState); if (tcur == NULL) @@ -605,16 +609,28 @@ PyGILState_Ensure(void) tcur->gilstate_counter = 0; current = 0; /* new thread state is never current */ } else else { current = PyThreadState_IsCurrent(tcur); if (current == 0) }
if (current == 0) { PyEval_RestoreThread(tcur); }
/* Update our counter in the thread-state - no need for locks: - tcur will remain valid as we hold the GIL. - the counter is safe as we are the only thread "allowed" to modify this value */ ++tcur->gilstate_counter;
if (need_init_threads) { /* At startup, Python has no concrete GIL. If PyGILState_Ensure() is called from a new thread for the first time, we need the create the GIL. */ PyEval_InitThreads(); }
return current ? PyGILState_LOCKED : PyGILState_UNLOCKED; }