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From "Varun Saxena (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (YARN-3137) CapacityScheduler.checkAccess unnecessarily grabs the scheduler lock
Date Thu, 05 Feb 2015 10:50:36 GMT

    [ https://issues.apache.org/jira/browse/YARN-3137?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14307036#comment-14307036
] 

Varun Saxena commented on YARN-3137:
------------------------------------

Agree, we can keep a specific R/W lock to handle queue hierarchy.
We however have another sub task of YARN-3091 i.e. YARN-3139 which looks at improving locks
of Capacity Scheduler.
These 2 look like dependent JIRAs'.

> CapacityScheduler.checkAccess unnecessarily grabs the scheduler lock
> --------------------------------------------------------------------
>
>                 Key: YARN-3137
>                 URL: https://issues.apache.org/jira/browse/YARN-3137
>             Project: Hadoop YARN
>          Issue Type: Sub-task
>    Affects Versions: 2.5.0
>            Reporter: Jason Lowe
>            Assignee: Varun Saxena
>
> The queues are stored in a ConcurrentHashMap and the code already checks for a null queue.
 At best we need to lock individual queues when processing the access check, but I don't see
why we need to grab the highly-contested scheduler lock to lookup which queue to use for the
hasAccess call.



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