Dynamic adjust instances of concurrentConsumers

[Wuaner]

I noticed that SimpleMessageListenerContainer has a property - concurrentConsumers; I use it to setting the count of concurrent consumers:

  <rabbit:listener-container connection-factory="connectionFactory" message-converter="jsonMessageConverter" concurrency="5" >
    <rabbit:listener queues="aQueue" ref="messageConsumer" method="handleMessage" />
  </rabbit:listener-container>

My question is, how can i dynamic adjusting the instance count of concurrentConsumers that based on queue depth(total count of message remaining in the queue)? when depth of aQueue is large, increasing the count of concurrentConsumers; when its small, decreasing it.

Besides:how can i get queue depth using spring-amqp API?

All reply will be appreciated.

Regards.

[Gary Russell]

No; the container doesn't currently support dynamic adjustment of the consumers; you have to stop/adjust/start the container to change it.

No, the AMQP protocol doesn't support getting queue depths. You can, however, make REST calls to the Rabbit Admin plugin to get this information.

[Wuaner]

thanks Gary.

I searching the web found that in rabbit-java-client API there is a method maybe can use to find a queue's depth:
http://lists.rabbitmq.com/pipermail/...ch/011656.html

Channel c = createChannel();
AMQP.Queue.DeclareOK ok = c.queueDeclarePassive("my.queue");
int messageCount = ok.getMessageCount();

Or use RESTul with Rabbit-Admin-plugin just as you suggested.

Cheers.