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https://issues.apache.org/jira/browse/QPID-5050?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13741143#comment-13741143
]
Philip Harvey commented on QPID-5050:
-------------------------------------
The patch looks fine on the whole. Some non-essential things I'd change:
* The comment on testExceptionListenerStopsConnection_IsAllowed (and arguably
the name) is misleading because you actually expect connection.stop() to throw
an exception. Similarly, the test should fail if this exception is not thrown.
* As discussed, neither of us are certain whether it would be appropriate to
commit the rather specific testExceptionListenerConnectionStopDeadlock test.
** I'm actually happy either way, with a slight preference for committing it
(it does at least test that you can do JMS work inside both the message
listener and the exception listener without anything blowing up, whether as a
deadlock or not).
> Clients calling Connection#stop() from within an ExceptionListener have
> potential for deadlock
> ----------------------------------------------------------------------------------------------
>
> Key: QPID-5050
> URL: https://issues.apache.org/jira/browse/QPID-5050
> Project: Qpid
> Issue Type: Bug
> Components: Java Client
> Affects Versions: 0.8, 0.10, 0.12, 0.14, 0.16, 0.18, 0.20, 0.22
> Reporter: Keith Wall
> Assignee: Philip Harvey
> Attachments:
> 0001-QPID-5050-Move-invocation-of-ExceptionListener-to-af.patch
>
>
> A deadlock possibility exists for client applications calling Connection#stop
> within an application owned ExceptionListener.
> Unfortunately a common messaging framework (Spring), installs such a
> ExceptionListener.
> In a recent support call, such a deadlock had occurred between the dispatcher
> thread (whose onMessage was in the process of creating a session) and a
> pooled thread bouncing a message back to the application. (The bounced
> messages is returned to the application via the exception listener).
> The deadlock involves the Dispatcher._lock and AMQConnection._failoverMutex.
> The deadlock was reproduced with a system test (attached to Jira) and
> deadlock captured with jstack -l <pid> (output below).
> {noformat}
> Dispatcher-1-Conn-4 pool-8-thread-1
> + acquires c888 (Dispatcher#_lock) + acquires ca68
> (AMQConnection#_failoverMutex)
> + tries to acquire ca68 + tries to acquire c888
> {noformat}
> {noformat}
> Found one Java-level deadlock:
> =============================
> "pool-8-thread-1":
> waiting to lock monitor 0x000000005b0d3560 (object 0x00000000f70bc888, a
> java.lang.Object),
> which is held by "Dispatcher-1-Conn-4"
> "Dispatcher-1-Conn-4":
> waiting to lock monitor 0x000000005b187308 (object 0x00000000f70bca68, a
> java.lang.Object),
> which is held by "pool-8-thread-1"
> Java stack information for the threads listed above:
> ===================================================
> "pool-8-thread-1":
> at
> org.apache.qpid.client.AMQSession$Dispatcher.setConnectionStopped(AMQSession.java:3276)
> - waiting to lock <0x00000000f70bc888> (a java.lang.Object)
> at org.apache.qpid.client.AMQSession.stop(AMQSession.java:2382)
> at org.apache.qpid.client.AMQConnection.stop(AMQConnection.java:835)
> at
> org.apache.qpid.test.unit.client.connection.ExceptionListenerTest$4.onException(ExceptionListenerTest.java:206)
> at
> org.apache.qpid.client.AMQConnection.exceptionReceived(AMQConnection.java:1329)
> - locked <0x00000000f70bca68> (a java.lang.Object)
> at
> org.apache.qpid.client.AMQSession_0_8$4.run(AMQSession_0_8.java:600)
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
> at java.lang.Thread.run(Thread.java:662)
> "Dispatcher-1-Conn-4":
> at
> org.apache.qpid.client.AMQConnectionDelegate_8_0.executeRetrySupport(AMQConnectionDelegate_8_0.java:333)
> - waiting to lock <0x00000000f70bca68> (a java.lang.Object)
> at
> org.apache.qpid.client.AMQConnection.executeRetrySupport(AMQConnection.java:624)
> at
> org.apache.qpid.client.failover.FailoverRetrySupport.execute(FailoverRetrySupport.java:102)
> at
> org.apache.qpid.client.AMQSession.createProducerImpl(AMQSession.java:2600)
> at
> org.apache.qpid.client.AMQSession.createProducer(AMQSession.java:1176)
> at
> org.apache.qpid.client.AMQSession.createProducer(AMQSession.java:98)
> at
> org.apache.qpid.test.unit.client.connection.ExceptionListenerTest$5.onMessage(ExceptionListenerTest.java:229)
> at
> org.apache.qpid.client.BasicMessageConsumer.notifyMessage(BasicMessageConsumer.java:744)
> at
> org.apache.qpid.client.BasicMessageConsumer.notifyMessage(BasicMessageConsumer.java:718)
> at
> org.apache.qpid.client.AMQSession$Dispatcher.notifyConsumer(AMQSession.java:3388)
> at
> org.apache.qpid.client.AMQSession$Dispatcher.dispatchMessage(AMQSession.java:3327)
> - locked <0x00000000f71747e0> (a java.lang.Object)
> - locked <0x00000000f70bc888> (a java.lang.Object)
> at
> org.apache.qpid.client.AMQSession$Dispatcher.access$900(AMQSession.java:3114)
> at org.apache.qpid.client.AMQSession.dispatch(AMQSession.java:3107)
> at
> org.apache.qpid.client.message.UnprocessedMessage.dispatch(UnprocessedMessage.java:54)
> at
> org.apache.qpid.client.AMQSession$Dispatcher.run(AMQSession.java:3250)
> at java.lang.Thread.run(Thread.java:662)
> Found 1 deadlock.
> {noformat}
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