Close #19576: PyGILState_Ensure() now initializes threads. At startup, Python
has no concrete GIL. If PyGILState_Ensure() is called from a new thread for the
first time and PyEval_InitThreads() was not called yet, a GIL needs to be
created.
diff --git a/Misc/NEWS b/Misc/NEWS
index 2c1df09..84f36b8 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -10,6 +10,11 @@
Core and Builtins
-----------------
+- Issue #19576: PyGILState_Ensure() now initializes threads. At startup, Python
+ has no concrete GIL. If PyGILState_Ensure() is called from a new thread for
+ the first time and PyEval_InitThreads() was not called yet, a GIL needs to be
+ created.
+
- Issue #17576: Deprecation warning emitted now when __int__() or __index__()
return not int instance.
diff --git a/Python/pystate.c b/Python/pystate.c
index 6be71de..a56e308 100644
--- a/Python/pystate.c
+++ b/Python/pystate.c
@@ -771,6 +771,11 @@
assert(autoInterpreterState); /* Py_Initialize() hasn't been called! */
tcur = (PyThreadState *)PyThread_get_key_value(autoTLSkey);
if (tcur == NULL) {
+ /* 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();
+
/* Create a new thread state for this thread */
tcur = PyThreadState_New(autoInterpreterState);
if (tcur == NULL)