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https://issues.apache.org/jira/browse/YARN-4416?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Naganarasimha G R updated YARN-4416:
------------------------------------
    Attachment: YARN-4416.v1.001.patch

Thanks for the comments [~wangda],
bq. queueCapacity, resource-usage has their own read/write lock.
Hence have removed unwanted synchronization on the methods

bq. numContainers is volatile.
as its volatile i have removed the synchronization for the get method also 
there was unnecessary override of getNumContainers in LeafQueue, hence removed 
it

bq. read/write lock could be added to OrderingPolicy. Read operations don't 
need synchronized. So getNumApplications doesn't need synchronized.
i have added locks for the access of {{schedulableEntities}} in 
*AbstractComparatorOrderingPolicy* but not completely sure of the modifications 
as there already synchronization on {{entitiesToReorder}}. So would like 
additional(/focused) review for this part in particular

> Deadlock due to synchronised get Methods in AbstractCSQueue
> -----------------------------------------------------------
>
>                 Key: YARN-4416
>                 URL: https://issues.apache.org/jira/browse/YARN-4416
>             Project: Hadoop YARN
>          Issue Type: Bug
>          Components: capacity scheduler, resourcemanager
>    Affects Versions: 2.7.1
>            Reporter: Naganarasimha G R
>            Assignee: Naganarasimha G R
>            Priority: Minor
>         Attachments: YARN-4416.v1.001.patch, deadlock.log
>
>
> While debugging in eclipse came across a scenario where in i had to get to 
> know the name of the queue but every time i tried to see the queue it was 
> getting hung. On seeing the stack realized there was a deadlock but on 
> analysis found out that it was only due to *queue.toString()* during 
> debugging as {{AbstractCSQueue.getAbsoluteUsedCapacity}} was synchronized.
> Still i feel {{AbstractCSQueue}}'s getter methods need not be synchronized 
> and better be handled through read and write locks.



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