How to use

setConsumersPerQueue

method

in

org.springframework.amqp.rabbit.listener.DirectMessageListenerContainer

/**
 * @param consumersPerQueue the consumersPerQueue.
 * @return the spec.
 * @see DirectMessageListenerContainer#setConsumersPerQueue(int)
 */
public DirectMessageListenerContainerSpec consumersPerQueue(int consumersPerQueue) {
  this.listenerContainer.setConsumersPerQueue(consumersPerQueue);
  return this;
}

/**
 * @param consumersPerQueue the consumersPerQueue.
 * @return the spec.
 * @see DirectMessageListenerContainer#setConsumersPerQueue(int)
 */
public DirectMessageListenerContainerSpec consumersPerQueue(int consumersPerQueue) {
  this.listenerContainer.setConsumersPerQueue(consumersPerQueue);
  return this;
}

dmlc.setConsumersPerQueue(this.consumersPerQueue);
container = dmlc;

@Override
protected void processMonitorTask() {
  long now = System.currentTimeMillis();
  synchronized (this.consumersMonitor) {
    long reduce = this.consumers.stream()
      .filter(c -> this.whenUsed.containsKey(c) && !this.inUseConsumerChannels.containsValue(c)
          && this.whenUsed.get(c) < now - getIdleEventInterval())
      .count();
    if (reduce > 0) {
      if (logger.isDebugEnabled()) {
        logger.debug("Reducing idle consumes by " + reduce);
      }
      this.consumerCount = (int) Math.max(0, this.consumerCount - reduce);
      super.setConsumersPerQueue(this.consumerCount);
    }
  }
}

@Override
protected void processMonitorTask() {
  long now = System.currentTimeMillis();
  synchronized (this.consumersMonitor) {
    long reduce = this.consumers.stream()
      .filter(c -> this.whenUsed.containsKey(c) && !this.inUseConsumerChannels.containsValue(c)
          && this.whenUsed.get(c) < now - getIdleEventInterval())
      .count();
    if (reduce > 0) {
      if (logger.isDebugEnabled()) {
        logger.debug("Reducing idle consumes by " + reduce);
      }
      this.consumerCount = (int) Math.max(0, this.consumerCount - reduce);
      super.setConsumersPerQueue(this.consumerCount);
    }
  }
}

@Override
protected void doStart() {
  if (!isRunning()) {
    this.consumerCount = 0;
    super.setConsumersPerQueue(0);
    super.doStart();
  }
}

@Override
protected void doStart() {
  if (!isRunning()) {
    this.consumerCount = 0;
    super.setConsumersPerQueue(0);
    super.doStart();
  }
}

@Override
protected void initializeContainer(DirectMessageListenerContainer instance, RabbitListenerEndpoint endpoint) {
  super.initializeContainer(instance, endpoint);
  if (this.taskScheduler != null) {
    instance.setTaskScheduler(this.taskScheduler);
  }
  if (this.monitorInterval != null) {
    instance.setMonitorInterval(this.monitorInterval);
  }
  if (endpoint != null && endpoint.getConcurrency() != null) {
    try {
      instance.setConsumersPerQueue(Integer.parseInt(endpoint.getConcurrency()));
    }
    catch (NumberFormatException e) {
      throw new IllegalStateException("Failed to parse concurrency: " + e.getMessage(), e);
    }
  }
  else if (this.consumersPerQueue != null) {
    instance.setConsumersPerQueue(this.consumersPerQueue);
  }
}

public DirectReplyToMessageListenerContainer(ConnectionFactory connectionFactory) {
  super(connectionFactory);
  super.setQueueNames(Address.AMQ_RABBITMQ_REPLY_TO);
  setAcknowledgeMode(AcknowledgeMode.NONE);
  super.setConsumersPerQueue(0);
  super.setIdleEventInterval(DEFAULT_IDLE);
}

public DirectReplyToMessageListenerContainer(ConnectionFactory connectionFactory) {
  super(connectionFactory);
  super.setQueueNames(Address.AMQ_RABBITMQ_REPLY_TO);
  setAcknowledgeMode(AcknowledgeMode.NONE);
  super.setConsumersPerQueue(0);
  super.setIdleEventInterval(DEFAULT_IDLE);
}

/**
 * Get the channel holder associated with a direct reply-to consumer; contains a
 * consumer epoch to prevent inappropriate releases.
 * @return the channel holder.
 */
public ChannelHolder getChannelHolder() {
  synchronized (this.consumersMonitor) {
    ChannelHolder channelHolder = null;
    while (channelHolder == null) {
      if (!isRunning()) {
        throw new IllegalStateException("Direct reply-to container is not running");
      }
      for (SimpleConsumer consumer : this.consumers) {
        Channel candidate = consumer.getChannel();
        if (candidate.isOpen() && this.inUseConsumerChannels.putIfAbsent(candidate, consumer) == null) {
          channelHolder = new ChannelHolder(candidate, consumer.incrementAndGetEpoch());
          this.whenUsed.put(consumer, System.currentTimeMillis());
          break;
        }
      }
      if (channelHolder == null) {
        this.consumerCount++;
        super.setConsumersPerQueue(this.consumerCount);
      }
    }
    return channelHolder;
  }
}

@Override
protected void initializeContainer(DirectMessageListenerContainer instance, RabbitListenerEndpoint endpoint) {
  super.initializeContainer(instance, endpoint);
  if (this.taskScheduler != null) {
    instance.setTaskScheduler(this.taskScheduler);
  }
  if (this.monitorInterval != null) {
    instance.setMonitorInterval(this.monitorInterval);
  }
  if (endpoint != null && endpoint.getConcurrency() != null) {
    try {
      instance.setConsumersPerQueue(Integer.parseInt(endpoint.getConcurrency()));
    }
    catch (NumberFormatException e) {
      throw new IllegalStateException("Failed to parse concurrency: " + e.getMessage(), e);
    }
  }
  else if (this.consumersPerQueue != null) {
    instance.setConsumersPerQueue(this.consumersPerQueue);
  }
  if (this.messagesPerAck != null) {
    instance.setMessagesPerAck(this.messagesPerAck);
  }
  if (this.ackTimeout != null) {
    instance.setAckTimeout(this.ackTimeout);
  }
}

/**
 * Get the channel holder associated with a direct reply-to consumer; contains a
 * consumer epoch to prevent inappropriate releases.
 * @return the channel holder.
 */
public ChannelHolder getChannelHolder() {
  synchronized (this.consumersMonitor) {
    ChannelHolder channelHolder = null;
    while (channelHolder == null) {
      if (!isRunning()) {
        throw new IllegalStateException("Direct reply-to container is not running");
      }
      for (SimpleConsumer consumer : this.consumers) {
        Channel candidate = consumer.getChannel();
        if (candidate.isOpen() && this.inUseConsumerChannels.putIfAbsent(candidate, consumer) == null) {
          channelHolder = new ChannelHolder(candidate, consumer.incrementAndGetEpoch());
          this.whenUsed.put(consumer, System.currentTimeMillis());
          break;
        }
      }
      if (channelHolder == null) {
        this.consumerCount++;
        super.setConsumersPerQueue(this.consumerCount);
      }
    }
    return channelHolder;
  }
}

@Test
public void testAdvice() throws Exception {
  CachingConnectionFactory cf = new CachingConnectionFactory("localhost");
  DirectMessageListenerContainer container = new DirectMessageListenerContainer(cf);
  container.setQueueNames(Q1, Q2);
  container.setConsumersPerQueue(2);
  final CountDownLatch latch = new CountDownLatch(2);
  container.setMessageListener(m -> latch.countDown());
  final CountDownLatch adviceLatch = new CountDownLatch(2);
  MethodInterceptor advice = i -> {
    adviceLatch.countDown();
    return i.proceed();
  };
  container.setAdviceChain(advice);
  container.setBeanName("advice");
  container.setConsumerTagStrategy(new Tag());
  container.afterPropertiesSet();
  container.start();
  RabbitTemplate template = new RabbitTemplate(cf);
  template.convertAndSend(Q1, "foo");
  template.convertAndSend(Q1, "bar");
  assertTrue(latch.await(10, TimeUnit.SECONDS));
  assertTrue(adviceLatch.await(10, TimeUnit.SECONDS));
  container.stop();
  assertTrue(consumersOnQueue(Q1, 0));
  assertTrue(consumersOnQueue(Q2, 0));
  assertTrue(activeConsumerCount(container, 0));
  assertEquals(0, TestUtils.getPropertyValue(container, "consumersByQueue", MultiValueMap.class).size());
  cf.destroy();
}

DirectMessageListenerContainer container = new DirectMessageListenerContainer(cf);
container.setQueueNames(Q1, Q2);
container.setConsumersPerQueue(4);
container.setMessageListener(new MessageListenerAdapter((ReplyingMessageListener<String, String>) in -> {
  if ("foo".equals(in) || "bar".equals(in)) {
assertTrue(consumersOnQueue(Q1, 4));
assertTrue(consumersOnQueue(Q2, 4));
container.setConsumersPerQueue(1);
assertTrue(consumersOnQueue(Q1, 1));
assertTrue(consumersOnQueue(Q2, 1));
container.setConsumersPerQueue(2);
assertTrue(consumersOnQueue(Q1, 2));
assertTrue(consumersOnQueue(Q2, 2));

DirectMessageListenerContainer container = new DirectMessageListenerContainer(cf);
container.setQueueNames(Q1, Q2);
container.setConsumersPerQueue(2);
container.setMessageListener(new MessageListenerAdapter((ReplyingMessageListener<String, String>) in -> {
  if ("foo".equals(in) || "bar".equals(in)) {

DirectMessageListenerContainer container = new DirectMessageListenerContainer(cf);
container.setQueueNames(Q1);
container.setConsumersPerQueue(2);
final AtomicReference<Channel> channel = new AtomicReference<>();
container.setMessageListener((ChannelAwareMessageListener) (m, c) -> {

container.setConsumersPerQueue(2);
container.setConsumersPerQueue(2);
container.setMessageListener(m -> { });
container.setFailedDeclarationRetryInterval(500);

cf.setExecutor(executor);
DirectMessageListenerContainer container = new DirectMessageListenerContainer(cf);
container.setConsumersPerQueue(2);
container.setMessageListener(new MessageListenerAdapter((ReplyingMessageListener<String, String>) in -> {
  if ("foo".equals(in) || "bar".equals(in)) {

cf.setExecutor(executor);
DirectMessageListenerContainer container = new DirectMessageListenerContainer(cf);
container.setConsumersPerQueue(2);
container.setMessageListener(new MessageListenerAdapter((ReplyingMessageListener<String, String>) in -> {
  if ("foo".equals(in) || "bar".equals(in)) {