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From "Sunil G (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (YARN-4416) Deadlock due to synchronised get Methods in AbstractCSQueue
Date Sun, 06 Dec 2015 14:44:10 GMT

    [ https://issues.apache.org/jira/browse/YARN-4416?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15043909#comment-15043909
] 

Sunil G commented on YARN-4416:
-------------------------------

bq.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

AbstractComparatorOrderingPolicy or OrderingPolicy is accessed under the lock from LeafQueue.
This dependency does exists now. I feel, its better to access this via LeafQueue lock.

> 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, YARN-4416.v1.002.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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