fix high CPU utilisation when two bus instances point to the same queue

gbus/bus.go

@@ -168,14 +168,6 @@ func (b *DefaultBus) bindServiceQueue() error {
 	return nil
 }
 
-func (b *DefaultBus) createAMQPChannel(conn *amqp.Connection) (*amqp.Channel, error) {
-	channel, e := conn.Channel()
-	if e != nil {
-		return nil, e
-	}
-	return channel, nil
-}
-
 //Start implements GBus.Start()
 func (b *DefaultBus) Start() error {
 
@@ -188,10 +180,10 @@ func (b *DefaultBus) Start() error {
 		return e
 	}
 
-	if b.ingressChannel, e = b.createAMQPChannel(b.ingressConn); e != nil {
+	if b.ingressChannel, e = b.ingressConn.Channel(); e != nil {
 		return e
 	}
-	if b.egressChannel, e = b.createAMQPChannel(b.egressConn); e != nil {
+	if b.egressChannel, e = b.egressConn.Channel(); e != nil {
 		return e
 	}
 
@@ -209,7 +201,7 @@ func (b *DefaultBus) Start() error {
 		TODO://the design is crap and needs to be refactored
 	*/
 	var amqpChan *amqp.Channel
-	if amqpChan, e = b.createAMQPChannel(b.egressConn); e != nil {
+	if amqpChan, e = b.egressConn.Channel(); e != nil {
 		b.Log().WithError(e).Error("failed to create amqp channel for transactional outbox")
 		return e
 	}
@@ -272,7 +264,7 @@ func (b *DefaultBus) createBusWorkers(workerNum uint) ([]*worker, error) {
 	workers := make([]*worker, 0)
 	for i := uint(0); i < workerNum; i++ {
 		//create a channel per worker as we can't share channels across go routines
-		amqpChan, createChanErr := b.createAMQPChannel(b.ingressConn)
+		amqpChan, createChanErr := b.ingressConn.Channel()
 		if createChanErr != nil {
 			return nil, createChanErr
 		}

gbus/worker.go

@@ -66,7 +66,7 @@ func (worker *worker) Start() error {
 	worker.rpcMessages = rpcmsgs
 
 	go worker.consumeMessages()
-
+	go worker.consumeRPC()
 	return nil
 }
 
@@ -93,43 +93,22 @@ func (worker *worker) createMessagesChannel(q amqp.Queue, consumerTag string) (<
 
 func (worker *worker) consumeMessages() {
 
-	//TODO:Handle panics due to tx errors so the consumption of messages will continue
-	for {
-
-		var isRPCreply bool
-		var delivery amqp.Delivery
-		var shouldProceed bool
-
-		select {
-
-		case <-worker.stop:
-			worker.log().Info("stopped consuming messages")
-			return
-		case msgDelivery, ok := <-worker.messages:
-			if ok {
-				shouldProceed = true
-			}
-			delivery = msgDelivery
-			isRPCreply = false
-		case rpcDelivery, ok := <-worker.rpcMessages:
-			if ok {
-				shouldProceed = true
-			}
-			delivery = rpcDelivery
-			isRPCreply = true
+	for msg := range worker.messages {
+		if msg.Body == nil || len(msg.Body) == 0 {
+			continue
 		}
+		worker.processMessage(msg, false)
+	}
+}
 
-		/*
-			as the bus shuts down and amqp connection is killed the messages channel (b.msgs) gets closed
-			and delivery is a zero value so in order not to panic down the road we return if bus is shutdown
-		*/
-		if shouldProceed {
+func (worker *worker) consumeRPC() {
 
-			worker.processMessage(delivery, isRPCreply)
+	for msg := range worker.rpcMessages {
+		if msg.Body == nil || len(msg.Body) == 0 {
+			continue
 		}
-
+		worker.processMessage(msg, true)
 	}
-
 }
 
 func (worker *worker) extractBusMessage(delivery amqp.Delivery) (*BusMessage, error) {