1 files changed, 24 insertions, 3 deletions

diff --git a/unix/tclUnixNotfy.c b/unix/tclUnixNotfy.c
index 51f0b1f..88e290e 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.
@@ -267,10 +276,22 @@ Tcl_InitNotifier(void)
      */
 
     Tcl_MutexLock(&notifierMutex);
+    /*
+     * 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 +305,7 @@ Tcl_InitNotifier(void)
     }
 
     Tcl_MutexUnlock(&notifierMutex);
-#endif
+#endif /* TCL_THREADS */
     return (ClientData) tsdPtr;
 }