title: RabbitMQ: prefetched messages processing
body: <p>I am using Spring AMQP to work with RabbitMQ. 
  Here is my configuration:</p>
  
  <pre><code>&lt;rabbit:connection-factory id="connectionFactory"
      host="${queue.host}" port="${queue.port}" /&gt;
  &lt;rabbit:template id="amqpTemplate" connection-factory="connectionFactory" /&gt;
  &lt;rabbit:admin connection-factory="connectionFactory" /&gt;
  &lt;rabbit:queue name="${queue.names}" durable="true"
      exclusive="false" /&gt;
  &lt;rabbit:listener-container
      connection-factory="connectionFactory" acknowledge="auto" error-handler="airbrakeHandler" prefetch="1000" &gt;
      &lt;rabbit:listener ref="consumer" queue-names="${queue.names}" /&gt;
  &lt;/rabbit:listener-container&gt;
  </code></pre>
  
  <p>As you can see the prefetchCount is 1000.</p>
  
  <p>I was wondering whether the the prefetched messages are processed in parallel in the consumer; that is, multiple threads calling the onMessage(Message message) method.
  Or are the messages rather processed sequentially; that is, one thread that iterates over the prefetched messages and calls on each message the  onMessage(Message message) method in a sequntial manner.</p>
  
  <p>I should note that the order of the processing is not important for me. Just the fact that they are processed one at a time.</p>
  
  <p>Thanks in advance.</p>