not close ch, because send data to closed channel will panic

broadcast.go

@@ -42,6 +42,12 @@ func (b *BroadcastString) AddListener(c chan string) chan string {
 	return c
 }
 
+func (b *BroadcastString) RemoveListener(c chan string) {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+	delete(b.writers, c)
+}
+
 type BufferBroadcast struct {
 	bs *BroadcastString
 

res/css/style.css

@@ -19,7 +19,7 @@ body {
 }
 
 .realtime-log {
-    height: 50em;
+    height: 40em;
 }
 
 .status {

web.go

@@ -64,7 +64,6 @@ func (s *Supervisor) stopAndWait(name string) error {
 		return nil
 	}
 	c := make(chan string, 0)
-	defer func() { close(c) }()
 	s.addStatusChangeListener(c)
 	p.Operate(StopEvent)
 	for {
@@ -335,7 +334,7 @@ func (s *Supervisor) wsEvents(w http.ResponseWriter, r *http.Request) {
 			// Question: type 1 ?
 			c.WriteMessage(1, []byte(message))
 		}
-		close(ch)
+		s.eventB.RemoveListener(ch)
 	}()
 	for {
 		mt, message, err := c.ReadMessage()