[
https://issues.apache.org/activemq/browse/AMQ-1686?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Gary Tully updated AMQ-1686:
----------------------------
Attachment: AMQ-1689.patch
the test case inclued does not actually reproduce the problem, it comes close
but the window to check paralell access is too small. Maybe someone else can
improve on it.
> Small window in wakeup logic for PooledTaskRunner - task can get executed in
> parallell
> --------------------------------------------------------------------------------------
>
> Key: AMQ-1686
> URL: https://issues.apache.org/activemq/browse/AMQ-1686
> Project: ActiveMQ
> Issue Type: Bug
> Components: Broker
> Affects Versions: 5.0.0
> Environment: windows XP
> Reporter: Gary Tully
> Attachments: AMQ-1689.patch
>
>
> org.apache.activemq.broker.region.cursors.CursorDurableTest fails on windows
> sometimes with the error:
> Exception in thread "Persistence Adaptor Task" java.lang.NullPointerException
> at
> org.apache.activemq.store.amq.AMQMessageStore$4.execute(AMQMessageStore.java:381)
> at
> org.apache.activemq.util.TransactionTemplate.run(TransactionTemplate.java:44)
> at
> org.apache.activemq.store.amq.AMQMessageStore.doAsyncWrite(AMQMessageStore.java:374)
> at
> org.apache.activemq.store.amq.AMQMessageStore.asyncWrite(AMQMessageStore.java:341)
> at
> org.apache.activemq.store.amq.AMQMessageStore$1.iterate(AMQMessageStore.java:95)
> at
> org.apache.activemq.thread.PooledTaskRunner.runTask(PooledTaskRunner.java:122)
> at
> org.apache.activemq.thread.PooledTaskRunner$1.run(PooledTaskRunner.java:43)
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:650)
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:675)
> at java.lang.Thread.run(Thread.java:595)
> Tests run: 1, Failures: 1, Errors: 0, Skipped: 0, Time elapsed: 303.672 sec
> <<< FAILURE!
> The problem appears to be in the interaction between wakup and runTask in
> PooledTaskRunner
> iterating is set to false in a finally and queued is checked in a separate
> sync block.
> if wakeup is called in this window, it can set queued and find iterating
> false so it will execute, and runTask will find queued true and it too will
> execute.
> the fix is to include the queued check in the finally block so that iterating
> and queued are checked at the same time. I will attach a patch with this fix.
> I attempted to reproduce this problem with a unit test but I did not have any
> real success. the window is quite small. I will include the unit test in case
> it can be improved upon.
> chirino merged a fix yesterday that addresses the symptom of this issue in a
> different way,
> http://svn.apache.org/viewvc?view=rev&revision=650956
> The added synchronisation means that parallel calls by the
> PooledTaskRunner.asyncWrite are serialised on the method access.
> This fix addresses the route cause and can negate the need for the
> synchronisation.
> fyi: In the test, the paralell calls can come from flush() and from the
> asyncWrite task.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
