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https://issues.apache.org/activemq/browse/AMQ-1490?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_40601
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Hiram Chirino commented on AMQ-1490:
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I reviewed you test case and noticed that your consumer uses the same
connection as the producer. It is possible to get into a deadlock situation
when this occurs. If your producer blocks due to it waiting space on the
broker, it will lock up the connection. At that point the consumer will not be
able to consume anymore messages either.
I believe your deadlocks will go away if you use separate connections for the
consumer and producer threads.
> Deadlocks (with JUnit tests)
> ----------------------------
>
> Key: AMQ-1490
> URL: https://issues.apache.org/activemq/browse/AMQ-1490
> Project: ActiveMQ
> Issue Type: Bug
> Components: Broker
> Affects Versions: 5.0.0
> Environment: Linux
> Reporter: Rainer Klute
> Fix For: 5.0.0
>
> Attachments: ActiveMQ_Testcases.jar
>
>
> For some time now there have been various bug reports about ActiveMQ
> "blocking", "not receiving messages", "running into a deadlock" etc. Since I
> encoutered such deadlocks now and then, too, I eventually wrote up a JUnit
> testing scenario for this stuff. I found out that deadlocks can be quite
> easily reproduced. The symptoms are that the producer thread is sending or
> committing while the consumer thread is receiving or committing - and none of
> them can advance. One of the threads is always stuck in a blocking queue.
> Here's a sample output of my testing class:
> An ActiveMQ deadlock has been discovered. The following threads seem to be
> involved:
> Thread "producer" is inactive since 16 seconds after 358719 status changes.
> The current status is COMMITTING
> sun.misc.Unsafe.park(Native Method)
> java.util.concurrent.locks.LockSupport.park(LockSupport.java:158)
>
> java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:1889)
> java.util.concurrent.ArrayBlockingQueue.take(ArrayBlockingQueue.java:317)
>
> org.apache.activemq.transport.FutureResponse.getResult(FutureResponse.java:40)
>
> org.apache.activemq.transport.ResponseCorrelator.request(ResponseCorrelator.java:76)
>
> org.apache.activemq.ActiveMQConnection.syncSendPacket(ActiveMQConnection.java:1172)
> org.apache.activemq.TransactionContext.commit(TransactionContext.java:259)
> org.apache.activemq.ActiveMQSession.commit(ActiveMQSession.java:494)
> de.rainer_klute.activemq.ProducerThread.run(ProducerThread.java:162)
> Thread "consumer" is inactive since 16 seconds after 1807 status changes.
> The current status is RECEIVING
> java.lang.Object.wait(Native Method)
> java.lang.Object.wait(Object.java:485)
>
> org.apache.activemq.MessageDispatchChannel.dequeue(MessageDispatchChannel.java:75)
>
> org.apache.activemq.ActiveMQMessageConsumer.dequeue(ActiveMQMessageConsumer.java:404)
>
> org.apache.activemq.ActiveMQMessageConsumer.receive(ActiveMQMessageConsumer.java:452)
>
> org.apache.activemq.ActiveMQMessageConsumer.receive(ActiveMQMessageConsumer.java:504)
> de.rainer_klute.activemq.ConsumerThread.run(ConsumerThread.java:183)
> The following factors seem to increase the probability of a deadlock:
> * small values for memoryUsage
> * working transacted in the consumer (not always necessary but "helps")
> * many messages in the persistence store (to be achieved via a long delay
> before the consumer starts to read messages)
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