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From "Rupert Smith" <rupertlssm...@googlemail.com>
Subject Re: [java] Deadlock issue in trunk
Date Mon, 17 Sep 2007 13:54:49 GMT
It looks to me that the message delivery lock is the more fundamental cause
of the dead lock. I can't figure out from the stack trace why the dispatcher
thread is holding that one (I suppose I should look at what the test is
doing to figure that out).

Can we swap the order of obtaining the locks in AMQSession.close(long
timeout) from

synchronized(_messageDeliveryLock)
synchronized (_connection.getFailoverMutex())

to

synchronized (_connection.getFailoverMutex())
synchronized(_messageDeliveryLock)

?

Unless that causes a different dead lock, it looks like it will fix the
problem.

Also, it looks to me that removing the failover mutex acquisition from
createTextMessage will be harmless enough.

Rupert


On 15/09/2007, Rajith Attapattu <rajith77@gmail.com> wrote:
>
> Hi All,
>
> When I run the latest version of trunk I get a hang on
> org.apache.qpid.test.unit.client.forwardall.CombinedTest
> kill -3 (thread dump) provides information to say there is a deadlock.
>
> I also noted that all AMQSession.createXXXMessage contains synchronization
> code.
> (in this case the deadlock happens inn AMQSession.createTextMessage trying
> to obtain the failover mutex)
>
> Do we really need this synchronization code when creating messages? I am
> not
> really convinced it is needed.
> Can someody explain the reason for that code block?
>
> Regard,
>
> Rajith
>
> I have attached the trace below.
>
> Found one Java-level deadlock:
> =============================
> "Dispatcher-Channel-1":
>   waiting to lock monitor 0x09ff950c (object 0x8b85a1a0, a
> java.lang.Object
> ),
>   which is held by "main"
> "main":
>   waiting to lock monitor 0x09ff964c (object 0x88ff0240, a
> java.lang.Object
> ),
>   which is held by "Dispatcher-Channel-1"
>
> Java stack information for the threads listed above:
> ===================================================
> "Dispatcher-Channel-1":
>         at org.apache.qpid.client.AMQSession.createTextMessage(
> AMQSession.java:1057)
>         - waiting to lock <0x8b85a1a0> (a java.lang.Object)
>         at org.apache.qpid.client.AMQSession.createTextMessage(
> AMQSession.java:1068)
>         at org.apache.qpid.test.unit.client.forwardall.Service.onMessage(
> Service.java:59)
>         at org.apache.qpid.client.BasicMessageConsumer.notifyMessage(
> BasicMessageConsumer.java:628)
>         at org.apache.qpid.client.BasicMessageConsumer.notifyMessage(
> BasicMessageConsumer.java:583)
>         at org.apache.qpid.client.AMQSession$Dispatcher.dispatchMessage(
> AMQSession.java:2579)
>         at org.apache.qpid.client.AMQSession$Dispatcher.run(
> AMQSession.java
> :2502)
>         - locked <0x88ff0240> (a java.lang.Object)
>         - locked <0x88ff0238> (a java.lang.Object)
> "main":
>         at org.apache.qpid.client.AMQSession.close(AMQSession.java:462)
>         - waiting to lock <0x88ff0240> (a java.lang.Object)
>         at org.apache.qpid.client.AMQConnection.closeAllSessions(
> AMQConnection.java:752)
>         at org.apache.qpid.client.AMQConnection.close(AMQConnection.java
> :673)
>         - locked <0x8b85a1a0> (a java.lang.Object)
>         at org.apache.qpid.client.AMQConnection.close(AMQConnection.java
> :659)
>         at org.apache.qpid.test.unit.client.forwardall.Service.close(
> Service.java:71)
>         at
> org.apache.qpid.test.unit.client.forwardall.ServiceCreator.closeSC(
> ServiceCreator.java:57)
>         at
> org.apache.qpid.test.unit.client.forwardall.ServiceCreator.closeAll(
> ServiceCreator.java:66)
>         at
> org.apache.qpid.test.unit.client.forwardall.CombinedTest.tearDown
> (CombinedTest.java:44)
>         at junit.framework.TestCase.runBare(TestCase.java:130)
>         at junit.framework.TestResult$1.protect(TestResult.java:106)
>         at junit.framework.TestResult.runProtected(TestResult.java:124)
>         at junit.framework.TestResult.run(TestResult.java:109)
>         at junit.framework.TestCase.run(TestCase.java:118)
>         at junit.framework.TestSuite.runTest(TestSuite.java:208)
>         at junit.framework.TestSuite.run(TestSuite.java:203)
>         at junit.extensions.TestDecorator.basicRun(TestDecorator.java:22)
>

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