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https://issues.apache.org/jira/browse/YARN-1929?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13966941#comment-13966941
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Karthik Kambatla commented on YARN-1929:
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Looks a little tricky. Observations from reading the code again:
# EmbeddedElectorService(EES) doesn't need to synchronize the serviceStart and
serviceStop methods. These methods call synchronized methods in
ActiveStandbyElector(ASE). Actually, given that the
ActiveStandbyElectorCallback methods implemented by EES are also called from
ASE in-process, we probably don't need to synchronize them either.
# AdminService(AS) doesn't need to synchronize the service* methods either.
AS#{start|stop}Server can be synchronized if need be.
# Removing above synchronizations alone wouldn't be enough because there would
still be a deadlock between (*ASE#processResult* -> EES#becomeActive ->
*AS#transitionToActive* -> *RM#transitionToActive*) and (RM#serviceStop ->
RM.super#serviceStop -> *RM.super#stop* -> AS#stop -> AS#serviceStop ->
EES#serviceStop -> *ASE#quitElection*), the methods in bold are synchronized.
We should probably revisit the synchronization of CompositeService#stop.
[[email protected]] - any suggestions?
> DeadLock in RM when automatic failover is enabled.
> --------------------------------------------------
>
> Key: YARN-1929
> URL: https://issues.apache.org/jira/browse/YARN-1929
> Project: Hadoop YARN
> Issue Type: Bug
> Components: resourcemanager
> Environment: Yarn HA cluster
> Reporter: Rohith
> Assignee: Karthik Kambatla
> Priority: Blocker
>
> Dead lock detected in RM when automatic failover is enabled.
> {noformat}
> Found one Java-level deadlock:
> =============================
> "Thread-2":
> waiting to lock monitor 0x00007fb514303cf0 (object 0x00000000ef153fd0, a
> org.apache.hadoop.ha.ActiveStandbyElector),
> which is held by "main-EventThread"
> "main-EventThread":
> waiting to lock monitor 0x00007fb514750a48 (object 0x00000000ef154020, a
> org.apache.hadoop.yarn.server.resourcemanager.EmbeddedElectorService),
> which is held by "Thread-2"
> {noformat}
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