Failed to receiveNoWait() immediately after connection.start()

Question

Hi,
I am using Sun MQ Platform Ed. 3.5. It seems that I have to Thread.sleep(1000) after connection.start() and before receiveNoWait(). Otherwise, I will always get Null Message.
The code i have is:
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QueueConnection connection = factory.createQueueConnection();
QueueSession session = connection.createQueueSession(false, javax.jms.Session.AUTO_ACKNOWLEDGE);
QueueReceiver receiver = session.createReceiver(queue);
connection.start();
// Need add "Thread.sleep(1000);". otherwise, it will always get NULL
Message message = receiver.receiveNoWait();
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Anybody meet this problem before?

Answer 1

This behavior is typical if you use prefetching of messages (client-side caching). The JMS server has to initially load the client's cache and the receiveNoWait() returns immediately. You might check the prefetch configuration of SunMQ (usually located somewhere in the connection factory configuration). Or just use receive(1000) for the very first message and receiceNoWait for the rest.
Be pracmatic! ;-)
-- Andreas