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https://issues.apache.org/jira/browse/TEZ-3297?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Rajesh Balamohan reassigned TEZ-3297:
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Assignee: Rajesh Balamohan
> Deadlock scenario in AM during ShuffleVertexManager auto reduce
> ---------------------------------------------------------------
>
> Key: TEZ-3297
> URL: https://issues.apache.org/jira/browse/TEZ-3297
> Project: Apache Tez
> Issue Type: Bug
> Reporter: Zhiyuan Yang
> Assignee: Rajesh Balamohan
> Priority: Critical
> Attachments: TEZ-3297.1.patch, TEZ-3297.2.branch-0.7.patch,
> TEZ-3297.2.patch, am_log, thread_dump
>
>
> Here is what's happening in the attached thread dump.
> App Pool thread #9 does the auto reduce on V2 and initializes the new edge
> manager, it holds the V2 write lock and wants read lock of source vertex V1.
> At the same time, another App Pool thread #2 schedules a task of V1 and gets
> the output spec, so it holds the V1 read lock and wants V2 read lock.
> Also, dispatcher thread wants the V1 write lock to begin the state machine
> transition. Since dispatcher thread is at the head of V1 ReadWriteLock queue,
> thread #9 cannot get V1 read lock even thread #2 is holding V1 read lock.
> This is a circular lock scenario. #2 blocks dispatcher, dispatcher blocks #9,
> and #9 blocks #2.
> There is no problem with ReadWriteLock behavior in this case. Please see this
> java bug report, http://bugs.java.com/bugdatabase/view_bug.do?bug_id=6816565.
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