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From "Naganarasimha G R (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (YARN-4416) Deadlock due to synchronised get Methods in AbstractCSQueue
Date Sat, 05 Dec 2015 10:05:11 GMT

    [ https://issues.apache.org/jira/browse/YARN-4416?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15042779#comment-15042779
] 

Naganarasimha G R commented on YARN-4416:
-----------------------------------------

Also there is unused variable in LeafQueue 
{code}
  // absolute capacity as a resource (based on cluster resource)
  private Resource absoluteCapacityResource = Resources.none();
...
private void updateAbsoluteCapacityResource(Resource clusterResource) {
    absoluteCapacityResource =
        Resources.multiplyAndNormalizeUp(resourceCalculator, labelManager
            .getResourceByLabel(RMNodeLabelsManager.NO_LABEL, clusterResource),
            queueCapacities.getAbsoluteCapacity(), minimumAllocation);
  }
{code}
Was not sure why this is required. If not required shall i delete it ?


> 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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