update

metrics/connection.go

@@ -30,6 +30,13 @@ var (
 		Name:      "send_blockings",
 		Help:      "Number of send blocking connections",
 	})
+
+	countMessageFromClosed = prometheus.NewCounter(prometheus.CounterOpts{
+		Namespace: promNamespace,
+		Subsystem: promSubsystem,
+		Name:      "sending_on_closed",
+		Help:      "Number of sending on closed connections",
+	})
 )
 
 func IncNewConnection() {
@@ -44,6 +51,10 @@ func IncSendBlocking() {
 	countSendBlocking.Inc()
 }
 
+func IncMessageFromClosed() {
+	countMessageFromClosed.Inc()
+}
+
 func SetCurrentConnections(num int) {
 	gaugeCurrentConnections.Set(float64(num))
 }

relay/wsserver.go

@@ -92,6 +92,9 @@ func (ws *WsServer) Run() {
 	for {
 		select {
 		case message := <-ws.localCh:
+			if _, ok := ws.clients[message.client]; !ok {
+				metrics.IncMessageFromClosed()
+			}
 			// local message could be "pub", "sub" or "ack" or "ping"
 			// pub/sub message handler may contain time-consuming operations(e.g. read/write redis)
 			// so put them in separate goroutine to avoid blocking wsserver main loop