routing: do not reacquire the lock for topology notifications

routing/notifications.go

@@ -113,15 +113,19 @@ func (r *ChannelRouter) notifyTopologyChange(topologyDiff *TopologyChange) {
 	r.RLock()
 	numClients := len(r.topologyClients)
 	r.RUnlock()
-	if numClients != 0 {
-		log.Tracef("Sending topology notification to %v clients %v",
-			numClients,
-			newLogClosure(func() string {
-				return spew.Sdump(topologyDiff)
-			}),
-		)
+
+	// Do not reacquire the lock twice unnecessarily.
+	if numClients == 0 {
+		return
 	}
 
+	log.Tracef("Sending topology notification to %v clients %v",
+		numClients,
+		newLogClosure(func() string {
+			return spew.Sdump(topologyDiff)
+		}),
+	)
+
 	r.RLock()
 	for _, client := range r.topologyClients {
 		client.wg.Add(1)