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https://issues.apache.org/jira/browse/AMQ-3605?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13160023#comment-13160023
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Timothy Bish commented on AMQ-3605:
-----------------------------------
Added a tentative patch to the TransportConnection class. Seems to resolve the
issue but I was seeing some failures in some unit tests locally and haven't
fully resolved if they are related to this change or just the normal flaky
tests we see fail sometimes. Most failures seem to be in the Network bridge
areas.
> NullPointerException in TransportConnection
> -------------------------------------------
>
> Key: AMQ-3605
> URL: https://issues.apache.org/jira/browse/AMQ-3605
> Project: ActiveMQ
> Issue Type: Bug
> Components: Transport
> Affects Versions: 5.5.0
> Environment: SLES 11 SP1
> java version "1.6.0_23"
> perl 5.10.0 + Net::Stomp 0.38_99
> Reporter: Tommy Lindgren
> Priority: Critical
> Labels: stomp
> Attachments: AMQ-3605-Patch.txt, StompDedicatedTaskRunnerTests.java,
> StompDedicatedTaskRunnerTests.java
>
>
> I'm running ActiveMQ 5.5.0 and clients using Net::Stomp 0.38_99 and I'm
> seeing infrequent NullPointerExceptions in TransportConnection:
> {noformat}
> Exception in thread "ActiveMQ Connection Dispatcher: /172.31.201.11:50607"
> java.lang.NullPointerException
> at
> org.apache.activemq.broker.TransportConnection.service(TransportConnection.java:327)
> at
> org.apache.activemq.broker.TransportConnection$1.onCommand(TransportConnection.java:179)
> at
> org.apache.activemq.transport.TransportFilter.onCommand(TransportFilter.java:69)
> at
> org.apache.activemq.transport.stomp.StompTransportFilter.sendToActiveMQ(StompTransportFilter.java:81)
> at
> org.apache.activemq.transport.stomp.StompSubscription.onMessageDispatch(StompSubscription.java:79)
> at
> org.apache.activemq.transport.stomp.ProtocolConverter.onActiveMQCommand(ProtocolConverter.java:596)
> at
> org.apache.activemq.transport.stomp.StompTransportFilter.oneway(StompTransportFilter.java:58)
> at
> org.apache.activemq.transport.MutexTransport.oneway(MutexTransport.java:40)
> at
> org.apache.activemq.broker.TransportConnection.dispatch(TransportConnection.java:1270)
> at
> org.apache.activemq.broker.TransportConnection.processDispatch(TransportConnection.java:815)
> at
> org.apache.activemq.broker.TransportConnection.iterate(TransportConnection.java:851)
> at
> org.apache.activemq.thread.DedicatedTaskRunner.runTask(DedicatedTaskRunner.java:104)
> at
> org.apache.activemq.thread.DedicatedTaskRunner$1.run(DedicatedTaskRunner.java:42)
> {noformat}
> This seems to happen 1-2 times per month or so but the result is dire: new
> messages aren't delivered to the affected client (you can see the number of
> pending messages increasing in the admin web interface) until the client or
> ActiveMQ is restarted.
> Relevant code snippet from TransportConnection.java,
> {noformat}
> 326 if (context != null) {
> 327 if (context.isDontSendReponse()) {
> {noformat}
> implies that we are dealing with a race condition. I'm not familiar with the
> ActiveMQ code base but it looks like it grabs a lock (serviceLock) before
> entering that function, so not sure what's going on.
> Since there's no timestamp associated with the stack trace I'm not completly
> sure what's going on on the client side. I've tried to reproduce it by
> writing a small script that uses Net::Stomp in a similar way to my real
> clients, but no luck so far.
> No idea if it's relevant, but my affected clients have been both consuming
> and producing, and sending/receiving on both topics and queues.
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