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From David Sitsky <>
Subject Large PendingQueueSize values for subscriptions on a queue with one message
Date Thu, 23 Aug 2007 08:22:13 GMT
I have an application which is using the latest snapshot of ActiveMQ 5.0.

I have a master JVM process which sends an item to a work-item queue.  I 
have worker JVM processes which pick up these items, process them, and 
possibly create new items into the work-item queue as a part of 
processing these messages.

The master sends a new work-item once the workers have completed all 
their work.

I have a situation where if there is only one worker JVM process (one 
consumer), everything works fine.  If there are two workers, they 
complete all of their work, the master sends the next work item to the 
queue, but they never get notified of this new message.

I know the message is sent, via the JMX console, and that the worker 
subscriptions are still active.

What is strange is the worker's subscriptions have large 
PendingQueueSize values, which seems odd, since they aren't processing 
any more messages.  The queue size is 1 after the master sends its new 

If I create a new worker process, it immediately gets the message from 
the master!

This happens with or without transactions, and with all sorts of 
pre-fetch sizes, using the same or separate Connections.

I've started to run the broker in my IDEA debugger to try and understand 
what is going on - but the fact that the PendingQueueSize are quite 
large, does this explain why the old workers don't get new messages? 
Does this sound like a bug?

Any suggestions on what I should look for?  I'm happy to dive into the 
code, but would appreciate some guidance.


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