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From "Karthik Kambatla (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (YARN-110) AM releases too many containers due to the protocol
Date Tue, 15 Dec 2015 09:57:46 GMT

    [ https://issues.apache.org/jira/browse/YARN-110?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15057747#comment-15057747
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Karthik Kambatla commented on YARN-110:
---------------------------------------

bq. but it looks like this increases latencies for competing AMs
Not sure I fully understand this. Care to elaborate with a concrete example? 

> AM releases too many containers due to the protocol
> ---------------------------------------------------
>
>                 Key: YARN-110
>                 URL: https://issues.apache.org/jira/browse/YARN-110
>             Project: Hadoop YARN
>          Issue Type: Bug
>          Components: resourcemanager, scheduler
>            Reporter: Arun C Murthy
>            Assignee: Arun C Murthy
>         Attachments: YARN-110.patch
>
>
> - AM sends request asking 4 containers on host H1.
> - Asynchronously, host H1 reaches RM and gets assigned 4 containers. RM at this point,
sets the value against H1 to
> zero in its aggregate request-table for all apps.
> - In the mean-while AM gets to need 3 more containers, so a total of 7 including the
4 from previous request.
> - Today, AM sends the absolute number of 7 against H1 to RM as part of its request table.
> - RM seems to be overriding its earlier value of zero against H1 to 7 against H1. And
thus allocating 7 more
> containers.
> - AM already gets 4 in this scheduling iteration, but gets 7 more, a total of 11 instead
of the required 7.



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