如果在您的应用程序中使用多个队列来处理消息,您可能会发现通过设置prefetchSize属性以限制一次从队列中取出消息的数量时遇到问题。这是因为默认情况下,ActiveMQ使用了一种称为“循环调度”的算法,该算法将prefetchSize除以队列数,从而平均分配在每个队列中。这可能会导致队列中的一些消息堆积,而另一些队列则没有。要解决这个问题,您可以使用以下代码作为参考,通过手动更改所需的预取数来设置每个队列的预取大小。
public class MultiQueueConsumer {
private static final Logger LOG = LoggerFactory.getLogger(MultiQueueConsumer.class);
private static final String BROKER_URL = "tcp://localhost:61616";
private static final String QUEUE_1_NAME = "queue1";
private static final String QUEUE_2_NAME = "queue2";
private static final int PREFETCH_SIZE = 5;
public static void main(String[] args) throws Exception {
ConnectionFactory connectionFactory = new ActiveMQConnectionFactory(BROKER_URL);
Connection connection = connectionFactory.createConnection();
connection.start();
Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
Queue queue1 = session.createQueue(QUEUE_1_NAME);
Queue queue2 = session.createQueue(QUEUE_2_NAME);
MessageConsumer consumer1 = session.createConsumer(queue1, null, getPREFETCH_SIZE(QUEUE_1_NAME, PREFETCH_SIZE));
MessageConsumer consumer2 = session.createConsumer(queue2, null, getPREFETCH_SIZE(QUEUE_2_NAME, PREFETCH_SIZE));
consumer1.setMessageListener(new MessageListenerImpl());
consumer2.setMessageListener(new MessageListenerImpl());
}
private static int getPREFETCH_SIZE(String queueName, int prefetchSize) {
DestinationStatistics destinationStatistics = null;
try {
destinationStatistics = getDestinationStatistics(queueName);
} catch (Exception e) {
LOG.error("Unable to get prefetch size for queue " + queueName + ", returning default size
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