fix possible goroutine leak on conn close, fix empty dev version in m…

…etrics

handler_sockjs.go

@@ -71,7 +71,7 @@ func (t *sockjsTransport) write(data ...[]byte) error {
 			// TODO: can actually be sent in single message as streaming JSON.
 			err := t.session.Send(string(payload))
 			if err != nil {
-				t.Close(DisconnectWriteError)
+				go t.Close(DisconnectWriteError)
 				return err
 			}
 			transportMessagesSent.WithLabelValues(transportSockJS).Inc()

handler_websocket.go

@@ -122,21 +122,21 @@ func (t *websocketTransport) write(data ...[]byte) error {
 		}
 		writer, err := t.conn.NextWriter(messageType)
 		if err != nil {
-			t.Close(DisconnectWriteError)
+			go t.Close(DisconnectWriteError)
 			return err
 		}
 		bytesOut := 0
 		for _, payload := range data {
 			n, err := writer.Write(payload)
 			if n != len(payload) || err != nil {
-				t.Close(DisconnectWriteError)
+				go t.Close(DisconnectWriteError)
 				return err
 			}
 			bytesOut += len(data)
 		}
 		err = writer.Close()
 		if err != nil {
-			t.Close(DisconnectWriteError)
+			go t.Close(DisconnectWriteError)
 			return err
 		}
 		if t.opts.writeTimeout > 0 {

node.go

@@ -179,7 +179,11 @@ func (n *Node) updateGauges() {
 	numClientsGauge.Set(float64(n.hub.NumClients()))
 	numUsersGauge.Set(float64(n.hub.NumUsers()))
 	numChannelsGauge.Set(float64(n.hub.NumChannels()))
-	buildInfoGauge.WithLabelValues(n.Config().Version).Set(1)
+	version := n.Config().Version
+	if version == "" {
+		version = "_"
+	}
+	buildInfoGauge.WithLabelValues(version).Set(1)
 }
 
 func (n *Node) updateMetrics() {