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https://issues.apache.org/jira/browse/OAK-279?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13442419#comment-13442419
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Michael Dürig commented on OAK-279:
-----------------------------------
Thanks for finding this. This seems to be broken in other ways also. I'll have
a look.
However calling {{stopped.countDown()}} only when {{stopping}} is {{true}} is
also incorrect: this introduces a race which might cause a call on {{stop()}}
to block forever.
> ChangeProcessor getting stuck while shutdown
> --------------------------------------------
>
> Key: OAK-279
> URL: https://issues.apache.org/jira/browse/OAK-279
> Project: Jackrabbit Oak
> Issue Type: Bug
> Components: core
> Affects Versions: 0.5
> Reporter: Chetan Mehrotra
> Assignee: Michael Dürig
> Priority: Minor
> Attachments: OAK-279.patch, stacktrace.txt
>
>
> o.a.j.oak.jcr.observation.ChangeProcessor is preventing system shutdown
> {noformat}
> "FelixStartLevel" daemon prio=10 tid=0x00007fbda846e000 nid=0x78d5 waiting on
> condition [0x00007fbda41ce000]
> java.lang.Thread.State: WAITING (parking)
> at sun.misc.Unsafe.park(Native Method)
> - parking to wait for <0x00000000b8931378> (a
> java.util.concurrent.CountDownLatch$Sync)
> at java.util.concurrent.locks.LockSupport.park(LockSupport.java:156)
> at
> java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:811)
> at
> java.util.concurrent.locks.AbstractQueuedSynchronizer.doAcquireSharedInterruptibly(AbstractQueuedSynchronizer.java:969)
> at
> java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireSharedInterruptibly(AbstractQueuedSynchronizer.java:1281)
> at java.util.concurrent.CountDownLatch.await(CountDownLatch.java:207)
> at
> org.apache.jackrabbit.oak.jcr.observation.ChangeProcessor.stop(ChangeProcessor.java:76)
> - locked <0x00000000b89312d0> (a
> org.apache.jackrabbit.oak.jcr.observation.ChangeProcessor)
> at
> org.apache.jackrabbit.oak.jcr.observation.ObservationManagerImpl.removeEventListener(ObservationManagerImpl.java:87)
> - locked <0x00000000b8931210> (a
> org.apache.jackrabbit.oak.jcr.observation.ObservationManagerImpl)
> at
> com.adobe.granite.workflow.core.eventsupport.JcrToWorkflowEventService.deactivate(JcrToWorkflowEventService.java:139)
> {noformat}
> Complete thread dump would be attached.
> Looking at ChangeProcessor.stop [1] method it appears that latch would not be
> cleared if an exception is thrown in the run() method and running variable
> remains set to true.
> One possible solution is perform {{stopped.countDown();}} in a finally block
> in case {{stopping}} is set to true. Further it appears that countDown should
> only be done in case stopping is true. Currently it is performed for every run
> [1]
> https://github.com/apache/jackrabbit-oak/blob/trunk/oak-jcr/src/main/java/org/apache/jackrabbit/oak/jcr/observation/ChangeProcessor.java#L72
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