How to kill consumers in activemq

Question

I am trying to get rid of all of the "Number of Consumers" in a certain queue. Whenever I purge/delete the queue, the number of consumers still remain if I ever create that queue with the same name again. Even with 0 pending messages, there are still 6 consumers.

My problem may have stemmed in my java code while not closing the session or connection.

I have tried both restarting and reinstalling the server.

Here is my producer code:

 private static String url = ActiveMQConnection.DEFAULT_BROKER_URL;

    public static String addElementToQueue(String queueName,String param1, String param2) throws JMSException, NamingException {
  // Getting JMS connection from the server and starting it
        ConnectionFactory connectionFactory =
                new ActiveMQConnectionFactory(url);
        Connection connection = connectionFactory.createConnection();

// JMS messages are sent and received using a Session. We will
        // create here a non-transactional session object. If you want
        // to use transactions you should set the first parameter to 'true'
        Session session = connection.createSession(false,
                Session.AUTO_ACKNOWLEDGE);

        // Destination represents here our queue on the
        // JMS server. You don't have to do anything special on the
        // server to create it, it will be created automatically.
        Destination destination = session.createQueue(queueName);

        // MessageProducer is used for sending messages (as opposed
        // to MessageConsumer which is used for receiving them)
        MessageProducer producer = session.createProducer(destination);   

        String queueMessage = param1+ "-" + param2;

        TextMessage message = session.createTextMessage(queueMessage);

        // Here we are sending the message!
        producer.send(message);

        connection.close();
        session.close();      // added after problem came up
        producer.close();     // added after problem came up

        return commandID;
}

Here is my consumer code:

 // URL of the JMS server
    private static String url = ActiveMQConnection.DEFAULT_BROKER_URL;

    public static Pair consumeNextElement(String queueName) throws JMSException {
        // Getting JMS connection from the server
        ConnectionFactory connectionFactory
                = new ActiveMQConnectionFactory(url);
        Connection connection = connectionFactory.createConnection();
        connection.start();   

        // Creating session for seding messages
        Session session = connection.createSession(false,
                Session.AUTO_ACKNOWLEDGE);

        // Getting the queue
        Destination destination = session.createQueue(queueName);

        // MessageConsumer is used for receiving (consuming) messages
        MessageConsumer consumer = session.createConsumer(destination);


        // Here we receive the message.
        // By default this call is blocking, which means it will wait
        // for a message to arrive on the queue.
        Message message = consumer.receive();

        // There are many types of Message and TextMessage
        // is just one of them. Producer sent us a TextMessage
        // so we must cast to it to get access to its .getText()
        // method.

        String[] parts = ((TextMessage)message).getText().split("-");
        Pair retVal = new Pair(parts[0], parts[1]);

        connection.close();
        session.close();        // added after problem came up
        consumer.close();      // added after problem came up  

        return retVal;
    }

Any thoughts?

Thanks.

Answer 1

The number of consumers is the number of listeners on the queue. Purging the queue should only remove the enqueued messages - those consumers listening will be unaffected.

The ability of the consumer to maintain/re-establish a connection may depend on the transport used to connect, and settings for the transport may allow for some tweaking of connection properties.

I frankly don't have much experience with these, but you might investigate Advisory Messages as a means to help debug your connections. The JMX interface or web console don't appear to be helpful beyond reporting consumer counts.