changeset:   87916:dc4e805ec68a
user:        Victor Stinner <victor.stinner@gmail.com>
date:        Fri Dec 13 01:46:43 2013 +0100
files:       Misc/NEWS Python/pystate.c
description:
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 -r c1a7ba57b4ff -r dc4e805ec68a Misc/NEWS
--- a/Misc/NEWS	Thu Dec 12 23:07:40 2013 +0100
+++ b/Misc/NEWS	Fri Dec 13 01:46:43 2013 +0100
@@ -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 -r c1a7ba57b4ff -r dc4e805ec68a Python/pystate.c
--- a/Python/pystate.c	Thu Dec 12 23:07:40 2013 +0100
+++ b/Python/pystate.c	Fri Dec 13 01:46:43 2013 +0100
@@ -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)