Hudson commented on YARN-4416:

FAILURE: Integrated in Hadoop-trunk-Commit #8978 (See 
YARN-4416. Deadlock due to synchronised get Methods in AbstractCSQueue. 
(wangda: rev 9b856d9787be5ec88ef34574b9b98755d7b669ea)
* hadoop-yarn-project/CHANGES.txt

> 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: Sub-task
>          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, 
> YARN-4416.v2.001.patch, YARN-4416.v2.002.patch, YARN-4416.v2.003.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.
> Hence we need to ensure following :
> # queueCapacity, resource-usage has their own read/write lock hence 
> synchronization is not req
> # numContainers is volatile hence synchronization is not req.
> # read/write lock could be added to Ordering Policy. Read operations don't 
> need synchronized. So {{getNumApplications}} doesn't need synchronized. 
> (First 2 will be handled in this jira and the third will be handled in 
> YARN-4443)

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