Java ActiveMQ client fails to receive messages

Question

I am trying to implement performance testing on ActiveMQ, so have setup a basic producer and consumer to send and receive messages across a queue. I have created a producer with no problems, getting it to write a specific number of messages to the queue:

 for(int i = 0; i < numberOfMessages; i++){
                try{
                    String message = generateText(sizeOfMessage);
                    produceMessage(message);
                }
                catch (Exception e) {
                    logger.error("Caught exception while sending message", e);
                }
            }

This continues to completion with no problems and I have confirmed this with checks on the admin website, that have the correct number of messages pending.

The problem occurs when I try to receive the messages from the queue. Using a simple consumer to read from the queue, it will read a various number of messages from the queue, but then will stop when trying to receive one of the messages. I can see that there are still messages in the queue to be read, but the client will not progress passed one of the messages. I am using a simple method to receive the messages:

Message message = jmsTemplate.receive();

and it works for some messages(about 20-30) but then just locks. It was suggested to me that some of the characters in the message may be an escape character (I was using a random string of varying length, due to this just being a performance test, not actually sending over any content) so I changed all messages to the same string, which is a repetition of the char '2' and still no luck. I am using Spring configuration to load all of the components needed to access the ActiveMQ queue, and the queue is running on my localhost.

Answer 1

Not many views on this yet, but for future reference if anyone has the same problem, I have found the solution. The configuration for activeMQ limits the amount of memory used by the senders and receivers before slowing them down, the default values given to me were:

<systemUsage>
            <systemUsage>
                <memoryUsage>
                    <memoryUsage limit="20 mb"/>
                </memoryUsage>
                <storeUsage>
                    <storeUsage limit="1 gb" name="foo"/>
                </storeUsage>
                <tempUsage>
                    <tempUsage limit="100 mb"/>
                </tempUsage>
            </systemUsage>
        </systemUsage>

I removed this configuration completely and now it works a dream. I'm carrying out performance testing, so you may want to put your own constraints in, but this was definitely the cause of my problems!

Answer 2

Its a classic issue with messaging; what to do with slow consumers. FWIW more recent ActiveMQ releases such as 5.2 allow you to spool to disk rather than blocking producers when memory gets low