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https://issues.apache.org/activemq/browse/AMQ-1251?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_40150
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David Sitsky commented on AMQ-1251:
-----------------------------------
Hi Hiram,
I have found an issue with your change I believe. While running my code, I
received the following exception:
[ActiveMQ Task] 881755 ERROR
org.apache.activemq.broker.region.Queue.worker-items - Failed to page in more
queue messages
java.lang.RuntimeException: not implemented
at
org.apache.activemq.broker.region.NullMessageReference.isDropped(NullMessageReference.java:47)
at
org.apache.activemq.broker.region.cursors.VMPendingMessageCursor.isEmpty(VMPendingMessageCursor.java:43)
at
org.apache.activemq.broker.region.PrefetchSubscription.add(PrefetchSubscription.java:119)
at
org.apache.activemq.broker.region.policy.RoundRobinDispatchPolicy.dispatch(RoundRobinDispatchPolicy.java:70)
at org.apache.activemq.broker.region.Queue.doDispatch(Queue.java:1054)
at
org.apache.activemq.broker.region.Queue.pageInMessages(Queue.java:1069)
at org.apache.activemq.broker.region.Queue.iterate(Queue.java:940)
at
org.apache.activemq.thread.PooledTaskRunner.runTask(PooledTaskRunner.java:118)
at
org.apache.activemq.thread.PooledTaskRunner$1.run(PooledTaskRunner.java:42)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown
Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
I can't look at the code where I am writing this from, but is this something
easy to fix? Thanks.
Cheers,
David
> 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
>
> Attachments: QueueWorkerPrefetchTest.java, TestActiveMQ.java,
> TestActiveMQSyncReceive.java
>
>
> 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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