1 files changed, 115 insertions, 4 deletions

diff --git a/unix/tclUnixNotfy.c b/unix/tclUnixNotfy.c
index 51f0b1f..ec721ca 100644
--- a/unix/tclUnixNotfy.c
+++ b/unix/tclUnixNotfy.c
@@ -112,7 +112,7 @@ typedef struct ThreadSpecificData {
     int eventReady;		/* True if an event is ready to be processed.
 				 * Used as condition flag together with waitCV
 				 * above. */
-#endif
+#endif /* TCL_THREADS */
 } ThreadSpecificData;
 
 static Tcl_ThreadDataKey dataKey;
@@ -128,6 +128,15 @@ 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 +194,7 @@ static Tcl_Condition notifierCV;
 
 static Tcl_ThreadId notifierThread;
 
-#endif
+#endif /* TCL_THREADS */
 
 /*
  * Static routines defined in this file.
@@ -193,7 +202,13 @@ 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);
 
 /*
@@ -267,11 +282,38 @@ 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++;
 
@@ -284,7 +326,7 @@ Tcl_InitNotifier(void)
     }
 
     Tcl_MutexUnlock(&notifierMutex);
-#endif
+#endif /* TCL_THREADS */
     return (ClientData) tsdPtr;
 }
 
@@ -1230,6 +1272,75 @@ 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 */