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Posted to dev@activemq.apache.org by "Timothy Bish (JIRA)" <ji...@apache.org> on 2013/04/27 00:52:16 UTC

[jira] [Resolved] (AMQ-4351) Deadlock when unsubscribing durable subscriber

     [ https://issues.apache.org/jira/browse/AMQ-4351?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Timothy Bish resolved AMQ-4351.
-------------------------------

    Resolution: Fixed

Fixed the stats issue on trunk
                
> Deadlock when unsubscribing durable subscriber
> ----------------------------------------------
>
>                 Key: AMQ-4351
>                 URL: https://issues.apache.org/jira/browse/AMQ-4351
>             Project: ActiveMQ
>          Issue Type: Bug
>          Components: Broker
>    Affects Versions: 5.7.0, 5.8.0
>         Environment: Setup: 
> Active MQ 5.7.0 with master/slave using JDBC store 
> Approx 3 - 5 concurrent durable subscribers 
> Approx 5 messages / sec 
>            Reporter: Tim Lammens
>            Assignee: Timothy Bish
>              Labels: patch
>             Fix For: 5.9.0
>
>         Attachments: ActiveMQUnsubscribeTest.java, dispatcher.patch
>
>
> We started using durable subscribers a week ago, and after the 4th durable subscriber unsubscribed (due to 1 hour inactivity), the system deadlocked. If the "Durable Subscriber Cleanup Timer" goes of at the wrong time, your entire server locks up. 
> Setup: 
> Active MQ 5.7.0 with master/slave using JDBC store 
> Approx 3 - 5 concurrent durable subscribers 
> Approx 5 messages / sec 
> Active MQ checks every 1 minute for subscribers which have been offline for 1 hour. 
> Locked threads: 
> "ActiveMQ Transport: tcp:///79.125.71.104:48082@8090": 
>         at org.apache.activemq.broker.region.Topic.doMessageSend(Topic.java:446) 
>         - waiting to lock <0x00000000c6228480> (a org.apache.activemq.broker.region.Topic) 
>         at org.apache.activemq.broker.region.Topic.send(Topic.java:427) 
>         at org.apache.activemq.broker.region.AbstractRegion.send(AbstractRegion.java:407) 
>         at org.apache.activemq.broker.region.RegionBroker.send(RegionBroker.java:503) 
> "ActiveMQ Transport: tcp:///79.125.71.104:47590@8090": 
>         at org.apache.activemq.broker.region.PrefetchSubscription.add(PrefetchSubscription.java:142) 
>         - waiting to lock <0x00000000c66ba050> (a java.lang.Object) 
>         at org.apache.activemq.broker.region.DurableTopicSubscription.add(DurableTopicSubscription.java:243) 
>         at org.apache.activemq.broker.region.policy.StrictOrderDispatchPolicy.dispatch(StrictOrderDispatchPolicy.java:58) 
> "ActiveMQ Durable Subscriber Cleanup Timer": 
>         at org.apache.activemq.broker.region.Topic.deactivate(Topic.java:288) 
>         - waiting to lock <0x00000000c6250670> (a java.util.concurrent.CopyOnWriteArrayList) 
>         at org.apache.activemq.broker.region.DurableTopicSubscription.deactivate(DurableTopicSubscription.java:184) 
>         - locked <0x00000000c66ba060> (a java.lang.Object) 
>         - locked <0x00000000c66ba050> (a java.lang.Object) 
>         at org.apache.activemq.broker.region.Topic.deleteSubscription(Topic.java:195) 
>         at org.apache.activemq.broker.region.TopicRegion.removeSubscription(TopicRegion.java:199) 
>         at org.apache.activemq.broker.region.TopicRegion.doCleanup(TopicRegion.java:99) 
> I have attached a patch which fixes the problem.
> Since there is only one dispatch policy per Topic, synchronisation can happen on the DispatchPolicy instead of on the consumers object which causes the deadlock.

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