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https://issues.apache.org/jira/browse/YARN-9163?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16735426#comment-16735426
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Hu Ziqian commented on YARN-9163:
---------------------------------
[~Tao Yang]，
Sorry, not found any new evidence yet.
> Deadlock when use yarn rmadmin -refreshQueues
> ---------------------------------------------
>
> Key: YARN-9163
> URL: https://issues.apache.org/jira/browse/YARN-9163
> Project: Hadoop YARN
> Issue Type: Bug
> Affects Versions: 3.1.1
> Reporter: Hu Ziqian
> Assignee: Hu Ziqian
> Priority: Blocker
> Attachments: YARN-9163.001.patch, rm.jstack.ziqian.log
>
>
> We have a cluster with 4000+ node and 10w+ app per-day in our production
> environment. When we use CLI: yarn rmadmin -refreshQueues, the active rm's
> process is stuck and ha doesn't happen, which means all the cluster stops
> service and we can only fix it by reboot active rm. We can reproduce on our
> production cluster every time but can't reproduce in our test environment
> which only has 100+ nodes and few apps. Both of our production and test
> environment use CapacityScheduler which open asyncSchedule function and
> preemption
> Analyzing the jstack of active rm, we found a dead lock in it:
> thread one（ refreshqueue thread）：
> * take write lock of capacity scheduler
> * take write lock of preemptionManager
> * wait read lock of root queue
> thread two (asyncScheduleThread)
> * take read lock of root queue
> * wait write lock of PreemptionManager
> thread three (ipc handler on 8030 which deal the allocate )
> * wait write lock of root queue
> These three thread work with a dead lock.
>
> The deadlock happens because of a "bug" of ReadWriteLock: writeLock request
> blocks future readLock despite policy
> unfair([https://bugs.openjdk.java.net/browse/JDK-6893626).] In order to solve
> this problem, we change the logic of refreshqueue thread, get a queue info
> copy first and avoid the thread to take write lock of preemptionManager and
> read lock of root queue at the same time.
>
> We test our new code in our production environment and the refresh queue
> command works well.
>
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