Weird behavior when counting messages on JMS queue

Question

I am using Active MQ and the Java JMS.

I want to count the number of messages on the queue.

One approach is counting the messeages with a browser:

    Queue queue = (Queue) session.createQueue(subject);
    QueueBrowser queueBrowser = session.createBrowser(queue);
    Enumeration<?> e = queueBrowser.getEnumeration();
    int numMsgs = 0;
    // count number of messages
    while (e.hasMoreElements()) {
    //    Message m = (Message) e.nextElement();
        e.nextElement();
        numMsgs++;
    }

But for a queue with 5000 pending requests, this only return 500.

Another approach is this (iterate all the messeages in the queue):

Message message= consumer.receive(500);
while(message!= null)
    {

        if (message instanceof TextMessage) 
        {
            TextMessage textMessage = (TextMessage) message;
       //     BytesMessage Byte

            System.out.println("Received message '"+ textMessage.getText() + "'");
        }
        if(message!=null)
            Messages_list.add(message);

        message = consumer.receive(1);
    }

But this also dont give the right amount of messages pending.

How can i confidently iterate akk the messages waiting in the queue?

Very weird behaviour, I've always had good experience with QueueBrowser. Silly questions but still - are you sure you are looking into right queue? How did you determine that there are 5000 messages? Imqadmin that's shipped with Glassfish often doesn't have up-to-date info about nr of messages, for example. — Miljen Mikic

Jason Sherman Jason Sherman · Accepted Answer · 2012-12-03T16:33:43

There is a bug in ActiveMQ that is preventing the browse from returning the actual number of messages. In this case the browse is only returning a single page of messages, which is set by the maxPageSize property and documented here: http://activemq.apache.org/per-destination-policies.html

ActiveMQ currently has a bug report on this issue and it is being tracked here: https://issues.apache.org/jira/browse/AMQ-4181. This issue has been resolved and is currently scheduled to be fixed in ActiveMQ 5.8.0.

Weird behavior when counting messages on JMS queue

2 Answers