#1683 prevent forking from interfering in threading storage

benjamin.peterson · benjamin.peterson · commit 5dff0d74c2cb · 2008-06-13T00:09:47.000Z
This should prevent some test_multiprocessing failures git-svn-id: http://svn.python.org/projects/python/trunk@64212 6015fed2-1504-0410-9fe1-9d1591cc4771
diff --git a/Include/pythread.h b/Include/pythread.h
@@ -40,6 +40,9 @@ PyAPI_FUNC(int) PyThread_set_key_value(int, void *);
 PyAPI_FUNC(void *) PyThread_get_key_value(int);
 PyAPI_FUNC(void) PyThread_delete_key_value(int key);
 
+/* Cleanup after a fork */
+PyAPI_FUNC(void) PyThread_ReInitTLS(void);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/Modules/signalmodule.c b/Modules/signalmodule.c
@@ -925,5 +925,6 @@ PyOS_AfterFork(void)
 	main_thread = PyThread_get_thread_ident();
 	main_pid = getpid();
 	_PyImport_ReInitLock();
+	PyThread_ReInitTLS();
 #endif
 }
diff --git a/Parser/intrcheck.c b/Parser/intrcheck.c
@@ -2,6 +2,7 @@
 /* Check for interrupts */
 
 #include "Python.h"
+#include "pythread.h"
 
 #ifdef QUICKWIN
 
@@ -172,5 +173,6 @@ PyOS_AfterFork(void)
 {
 #ifdef WITH_THREAD
 	PyEval_ReInitThreads();
+	PyThread_ReInitTLS();
 #endif
 }
diff --git a/Python/thread.c b/Python/thread.c
@@ -381,4 +381,35 @@ PyThread_delete_key_value(int key)
 	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 */

Original file line number	Diff line number	Diff line change
`@@ -40,6 +40,9 @@ PyAPI_FUNC(int) PyThread_set_key_value(int, void *);`
`40`	`40`	`PyAPI_FUNC(void *) PyThread_get_key_value(int);`
`41`	`41`	`PyAPI_FUNC(void) PyThread_delete_key_value(int key);`
`42`	`42`
	`43`	`+/* Cleanup after a fork */`
	`44`	`+PyAPI_FUNC(void) PyThread_ReInitTLS(void);`
	`45`	`+`
`43`	`46`	`#ifdef __cplusplus`
`44`	`47`	`}`
`45`	`48`	`#endif`
Original file line number	Diff line number	Diff line change
`@@ -925,5 +925,6 @@ PyOS_AfterFork(void)`
`925`	`925`	`main_thread = PyThread_get_thread_ident();`
`926`	`926`	`main_pid = getpid();`
`927`	`927`	`_PyImport_ReInitLock();`
	`928`	`+ PyThread_ReInitTLS();`
`928`	`929`	`#endif`
`929`	`930`	`}`
Original file line number	Diff line number	Diff line change
`@@ -2,6 +2,7 @@`
`2`	`2`	`/* Check for interrupts */`
`3`	`3`
`4`	`4`	`#include "Python.h"`
	`5`	`+#include "pythread.h"`
`5`	`6`
`6`	`7`	`#ifdef QUICKWIN`
`7`	`8`
`@@ -172,5 +173,6 @@ PyOS_AfterFork(void)`
`172`	`173`	`{`
`173`	`174`	`#ifdef WITH_THREAD`
`174`	`175`	`PyEval_ReInitThreads();`
	`176`	`+ PyThread_ReInitTLS();`
`175`	`177`	`#endif`
`176`	`178`	`}`