commit d29feccec3ce3dcd9ab3100f8956171c70ec3027
author Łukasz Langa <lukasz@langa.pl> Mon May 22 22:23:05 2017 -0700
committer GitHub <noreply@github.com> Mon May 22 22:23:05 2017 -0700
tree 20d4b6ea09a7663a3bae3313f6ca96f109258d92
parent 1398b1bc7d80df5bde17041e7ec0a3bdbf54b19e

[3.6] bpo-30395 _PyGILState_Reinit deadlock fix (GH-1734) (#1740)

head_lock could be held by another thread when fork happened. We should
reset it to avoid deadlock.
(cherry picked from commit f82c951d1c5416f3550d544e50ff5662d3836e73)

Python/pystate.c

diff --git a/Python/pystate.c b/Python/pystate.c
index 65c244e..ccb0092 100644
--- a/Python/pystate.c
+++ b/Python/pystate.c
@@ -743,6 +743,10 @@
 void
 _PyGILState_Reinit(void)
 {
+#ifdef WITH_THREAD
+    head_mutex = NULL;
+    HEAD_INIT();
+#endif
     PyThreadState *tstate = PyGILState_GetThisThreadState();
     PyThread_delete_key(autoTLSkey);
     if ((autoTLSkey = PyThread_create_key()) == -1)