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https://issues.apache.org/activemq/browse/AMQ-1251?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_39998
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David Sitsky commented on AMQ-1251:
-----------------------------------

Can you explain how this issue is resolved?  I see this issue still occurring 
with a svn checkout of trunk from yesterday (revision number 568479).  From 
what I can see, RoundRobinDispatchPolicy hasn't been changed as recommended by 
the author of this bug.

Was there any code committed to fix this bug?  If so, what was it?

I see exactly the same issue - after a while in my application, the consumers 
stop consuming messages, and I can confirm via JMX there are a couple of 
messages left in a persistent queue.  When I start up a new process which is a 
consumer for this queue, it immediately gets these messages, and the older 
consumers never receive any more, despite having subscriptions to the queue (as 
confirmed by JMX).



> Broker stops delivering messages to some consumers
> --------------------------------------------------
>
>                 Key: AMQ-1251
>                 URL: https://issues.apache.org/activemq/browse/AMQ-1251
>             Project: ActiveMQ
>          Issue Type: Bug
>          Components: Broker
>    Affects Versions: 4.1.0
>         Environment: WinXP
>            Reporter: Vadim Pesochinskiy
>            Assignee: Rob Davies
>             Fix For: 5.0.0
>
>
> I have around 40 consumers taking messages from a single queue. After awhile 
> 1 or 2 consumers stop receiveing any messages. Going to JMX and stopping 
> corresponding connection causes re-connect and messages are delivered again.
> I reproduced it twice in QA enviroment and now it happened in production. I 
> tried to instrument the code and set the log in debug, but that changed 
> timing and I failed to reproduce it after the changes.
> I suspect that runtime association b/w Queue and Consumer objects is lost on 
> the Broker side. 
> One of the suspects is the empty catch block in the RoundRobinDispatchPolicy 
> (line 64) class. It is possible that the CopyOnWrite array list is messed up 
> and it fails when removed consumer is added back. 
> BTW CopyOnWrite list is good when you mostly read, but not so good when you 
> write for every message delivery and empty catch blocks are bad in any case.
> if (firstMatchingConsumer != null) {
>       // Rotate the consumer list.
>       try {
>                 consumers.remove(firstMatchingConsumer);
>                 consumers.add(firstMatchingConsumer);
>       } catch (Throwable bestEffort) {
>       }
> }

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