Issue #10517: After fork(), reinitialize the TLS used by the PyGILState_*

pitrou · pitrou · commit 9ea1c8d7d73a · 2011-04-27T19:30:16.000+02:00
APIs, to avoid a crash with the pthread implementation in RHEL 5.  Patch
by Charles-François Natali.
diff --git a/Include/pystate.h b/Include/pystate.h
@@ -132,6 +132,7 @@ PyAPI_FUNC(void) PyThreadState_Clear(PyThreadState *);
 PyAPI_FUNC(void) PyThreadState_Delete(PyThreadState *);
 #ifdef WITH_THREAD
 PyAPI_FUNC(void) PyThreadState_DeleteCurrent(void);
+PyAPI_FUNC(void) _PyGILState_Reinit(void);
 #endif
 
 PyAPI_FUNC(PyThreadState *) PyThreadState_Get(void);
diff --git a/Misc/NEWS b/Misc/NEWS
@@ -10,6 +10,10 @@ What's New in Python 3.3 Alpha 1?
 Core and Builtins
 -----------------
 
+- Issue #10517: After fork(), reinitialize the TLS used by the PyGILState_*
+  APIs, to avoid a crash with the pthread implementation in RHEL 5.  Patch
+  by Charles-François Natali.
+
 - Issue #10914: Initialize correctly the filesystem codec when creating a new
   subinterpreter to fix a bootstrap issue with codecs implemented in Python, as
   the ISO-8859-15 codec.
diff --git a/Modules/signalmodule.c b/Modules/signalmodule.c
@@ -991,6 +991,7 @@ void
 PyOS_AfterFork(void)
 {
 #ifdef WITH_THREAD
+    _PyGILState_Reinit();
     PyEval_ReInitThreads();
     main_thread = PyThread_get_thread_ident();
     main_pid = getpid();
diff --git a/Python/pystate.c b/Python/pystate.c
@@ -586,6 +586,23 @@ _PyGILState_Fini(void)
     autoInterpreterState = NULL;
 }
 
+/* Reset the TLS key - called by PyOS_AfterFork.
+ * This should not be necessary, but some - buggy - pthread implementations
+ * don't flush TLS on fork, see issue #10517.
+ */
+void
+_PyGILState_Reinit(void)
+{
+    PyThreadState *tstate = PyGILState_GetThisThreadState();
+    PyThread_delete_key(autoTLSkey);
+    if ((autoTLSkey = PyThread_create_key()) == -1)
+        Py_FatalError("Could not allocate TLS entry");
+
+    /* re-associate the current thread state with the new key */
+    if (PyThread_set_key_value(autoTLSkey, (void *)tstate) < 0)
+        Py_FatalError("Couldn't create autoTLSkey mapping");
+}
+
 /* When a thread state is created for a thread by some mechanism other than
    PyGILState_Ensure, it's important that the GILState machinery knows about
    it so it doesn't try to create another thread state for the thread (this is

Original file line number	Diff line number	Diff line change
`@@ -991,6 +991,7 @@ void`
`991`	`991`	`PyOS_AfterFork(void)`
`992`	`992`	`{`
`993`	`993`	`#ifdef WITH_THREAD`
	`994`	`+ _PyGILState_Reinit();`
`994`	`995`	`PyEval_ReInitThreads();`
`995`	`996`	`main_thread = PyThread_get_thread_ident();`
`996`	`997`	`main_pid = getpid();`