Question

I am relatively new to JMS and have encountered a weird problem implementing my first real application. I’m desporate for any help or advice.

Background: I use AtiveMQ (java) as the message broker with non-transacted, non-persitent queues.

The Design: I have a straight forward producer/consumer system based around a single queue. A number of nodes(currently 2) place messages onto/ consume from the queue. Selectors are used to filter which messages a node recieves.

The Problem: The producer succesfully places its items on to the queue (i have verified they are there using the web interface) however the consumers remain blocked and do not read them. Only when i close the JMS connection in the producer do the consumers jump into life and consume the messages as expected.

This bevaior seems very weird to me, surely you shouldnt have to completely hang up the producer connection for the consumers to be able to read from the queue. I must have made a mistake somewhere(possibly with sessions) but the at the moment the number of things that could be wrong is to large and i have no idea what would cause this behaviour.

Any hints as to a solution, the cause of the problem or just how to continue debugging would be greatly appreciated.

Thanks for your time,

P.S If you requrie any additional information i am happy to provide it

Answer 1

Hard to say without seeing the code, but it sounds like the producer is transacted. You should not have to close the producer in order for the consumers to receive a message but a transacted producer won’t send it messages until you call commit. Other things to check is that the connection has been started. Also if you have many consumers you should look at the prefetch setting to ensure that one consumer doesn’t hog all the messages, setting to prefetch of 1 might be needed, but hard to say without further insight into your use case.