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authorjan.nijtmans <nijtmans@users.sourceforge.net>2013-08-01 12:54:16 (GMT)
committerjan.nijtmans <nijtmans@users.sourceforge.net>2013-08-01 12:54:16 (GMT)
commit9f6079e31a653421685fd3a5971bec5e3fff4b8c (patch)
tree37d9a3021fd8c84d7945fe3968b2236653648c5c /unix
parent9bfd2fab46c184c9b9e968190461f706c8729572 (diff)
parent5a3ead51fc13cea189ea37817652f2fd83cd5b43 (diff)
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Tcl_InitNotifier: Bug [a0bc856dcd]. Start notifier thread again if we were forked, to solve Rivet bug 55153
Diffstat (limited to 'unix')
-rw-r--r--unix/tclUnixNotfy.c113
1 files changed, 112 insertions, 1 deletions
diff --git a/unix/tclUnixNotfy.c b/unix/tclUnixNotfy.c
index aacc8d2d..c6c9759 100644
--- a/unix/tclUnixNotfy.c
+++ b/unix/tclUnixNotfy.c
@@ -120,6 +120,15 @@ static Tcl_ThreadDataKey dataKey;
static int notifierCount = 0;
/*
+ * The following static stores the process ID of the initialized notifier
+ * thread. If it changes, we have passed a fork and we should start a new
+ * notifier thread.
+ *
+ * You must hold the notifierMutex lock before accessing this variable.
+ */
+static pid_t processIDInitialized = 0;
+
+/*
* The following variable points to the head of a doubly-linked list of
* ThreadSpecificData structures for all threads that are currently waiting on
* an event.
@@ -185,7 +194,13 @@ static Tcl_ThreadId notifierThread;
#ifdef TCL_THREADS
static void NotifierThreadProc(ClientData clientData);
-#endif
+#ifdef HAVE_PTHREAD_ATFORK
+static int atForkInit = 0;
+static void AtForkPrepare(void);
+static void AtForkParent(void);
+static void AtForkChild(void);
+#endif /* HAVE_PTHREAD_ATFORK */
+#endif /* TCL_THREADS */
static int FileHandlerEventProc(Tcl_Event *evPtr, int flags);
/*
@@ -275,11 +290,38 @@ Tcl_InitNotifier(void)
*/
Tcl_MutexLock(&notifierMutex);
+#ifdef HAVE_PTHREAD_ATFORK
+ /*
+ * Install pthread_atfork handlers to reinitialize the notifier in the
+ * child of a fork.
+ */
+
+ if (!atForkInit) {
+ int result = pthread_atfork(AtForkPrepare, AtForkParent, AtForkChild);
+
+ if (result) {
+ Tcl_Panic("Tcl_InitNotifier: pthread_atfork failed");
+ }
+ atForkInit = 1;
+ }
+#endif
+ /*
+ * Check if my process id changed, e.g. I was forked
+ * In this case, restart the notifier thread and close the
+ * pipe to the original notifier thread
+ */
+ if (notifierCount > 0 && processIDInitialized != getpid()) {
+ notifierCount = 0;
+ processIDInitialized = 0;
+ close(triggerPipe);
+ triggerPipe = -1;
+ }
if (notifierCount == 0) {
if (TclpThreadCreate(&notifierThread, NotifierThreadProc, NULL,
TCL_THREAD_STACK_DEFAULT, TCL_THREAD_JOINABLE) != TCL_OK) {
Tcl_Panic("Tcl_InitNotifier: unable to start notifier thread");
}
+ processIDInitialized = getpid();
}
notifierCount++;
@@ -1270,6 +1312,75 @@ NotifierThreadProc(
TclpThreadExit(0);
}
+
+#ifdef HAVE_PTHREAD_ATFORK
+/*
+ *----------------------------------------------------------------------
+ *
+ * AtForkPrepare --
+ *
+ * Lock the notifier in preparation for a fork.
+ *
+ * Results:
+ * None.
+ *
+ * Side effects:
+ * None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void
+AtForkPrepare(void)
+{
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * AtForkParent --
+ *
+ * Unlock the notifier in the parent after a fork.
+ *
+ * Results:
+ * None.
+ *
+ * Side effects:
+ * None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void
+AtForkParent(void)
+{
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * AtForkChild --
+ *
+ * Unlock and reinstall the notifier in the child after a fork.
+ *
+ * Results:
+ * None.
+ *
+ * Side effects:
+ * None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void
+AtForkChild(void)
+{
+ notifierMutex = NULL;
+ notifierCV = NULL;
+ Tcl_InitNotifier();
+}
+#endif /* HAVE_PTHREAD_ATFORK */
+
#endif /* TCL_THREADS */
#endif /* !HAVE_COREFOUNDATION */