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https://issues.apache.org/jira/browse/YARN-4047?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14696054#comment-14696054
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Jian He commented on YARN-4047:
-------------------------------

lgtm +1


> ClientRMService getApplications has high scheduler lock contention
> ------------------------------------------------------------------
>
>                 Key: YARN-4047
>                 URL: https://issues.apache.org/jira/browse/YARN-4047
>             Project: Hadoop YARN
>          Issue Type: Bug
>          Components: resourcemanager
>            Reporter: Jason Lowe
>            Assignee: Jason Lowe
>              Labels: 2.6.1-candidate
>         Attachments: YARN-4047.001.patch
>
>
> The getApplications call can be particuarly expensive because the code can 
> call checkAccess on every application being tracked by the RM.  checkAccess 
> will often call scheduler.checkAccess which will grab the big scheduler lock. 
>  This can cause a lot of contention with the scheduler thread which is busy 
> trying to process node heartbeats, app allocation requests, etc.



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