Backport of r64212
Issue #1683: prevent forking from interfering in threading storage.
diff --git a/Python/thread.c b/Python/thread.c
index be4d092..9cf509c 100644
--- a/Python/thread.c
+++ b/Python/thread.c
@@ -391,4 +391,35 @@
PyThread_release_lock(keymutex);
}
+/* Forget everything not associated with the current thread id.
+ * This function is called from PyOS_AfterFork(). It is necessary
+ * because other thread ids which were in use at the time of the fork
+ * may be reused for new threads created in the forked process.
+ */
+void
+PyThread_ReInitTLS(void)
+{
+ long id = PyThread_get_thread_ident();
+ struct key *p, **q;
+
+ if (!keymutex)
+ return;
+
+ /* As with interpreter_lock in PyEval_ReInitThreads()
+ we just create a new lock without freeing the old one */
+ keymutex = PyThread_allocate_lock();
+
+ /* Delete all keys which do not match the current thread id */
+ q = &keyhead;
+ while ((p = *q) != NULL) {
+ if (p->id != id) {
+ *q = p->next;
+ free((void *)p);
+ /* NB This does *not* free p->value! */
+ }
+ else
+ q = &p->next;
+ }
+}
+
#endif /* Py_HAVE_NATIVE_TLS */