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https://issues.apache.org/jira/browse/YARN-6029?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Tao Yang updated YARN-6029:
---------------------------
    Attachment: YARN-6029.001.patch
                deadlock.jstack

> CapacityScheduler deadlock when ParentQueue#getQueueUserAclInfo is called by 
> Thread_A at the moment that Thread_B calls LeafQueue#assignContainers to 
> release a reserved container
> ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: YARN-6029
>                 URL: https://issues.apache.org/jira/browse/YARN-6029
>             Project: Hadoop YARN
>          Issue Type: Bug
>          Components: capacityscheduler
>    Affects Versions: 2.8.0
>            Reporter: Tao Yang
>            Assignee: Tao Yang
>         Attachments: YARN-6029.001.patch, deadlock.jstack
>
>
> When ParentQueue#getQueueUserAclInfo is called (e.g. a client calls 
> YarnClient#getQueueAclsInfo) just at the moment that 
> LeafQueue#assignContainers is called and before notifying parent queue to 
> release resource (should release a reserved container), then ResourceManager 
> can deadlock. I found this problem on our testing environment for hadoop2.8.
> Reproduce the deadlock in chronological order
> * 1. Thread A (ResourceManager Event Processor) calls synchronized 
> LeafQueue#assignContainers (got LeafQueue instance lock of queue root.a)
> * 2. Thread B (IPC Server handler) calls synchronized 
> ParentQueue#getQueueUserAclInfo (got ParentQueue instance lock of queue 
> root), iterates over children queue acls and is blocked when calling 
> synchronized LeafQueue#getQueueUserAclInfo (the LeafQueue instance lock of 
> queue root.a is hold by Thread A)
> * 3. Thread A wants to inform the parent queue that a container is being 
> completed and is blocked when invoking synchronized 
> ParentQueue#internalReleaseResource method (the ParentQueue instance lock of 
> queue root is hold by Thread B)
> I think the synchronized modifier of LeafQueue#getQueueUserAclInfo can be 
> removed to solve this problem, since this method appears to not affect fields 
> of LeafQueue instance.
> Attach patch with UT for review.



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