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Posted to yarn-issues@hadoop.apache.org by "Wangda Tan (JIRA)" <ji...@apache.org> on 2016/05/01 20:03:13 UTC
[jira] [Commented] (YARN-4390) Do surgical preemption based on
reserved container in CapacityScheduler
[ https://issues.apache.org/jira/browse/YARN-4390?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15265857#comment-15265857 ]
Wangda Tan commented on YARN-4390:
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[~eepayne],
Yeah you're correct, I think YARN-4280 can cause such excessive preemption. For example, if a 2G preemption is required for one container reservation. It is possible that FifoCandidateSelector select 2 * 1G containers, and the two containers cannot be preempted *at the same time*, reservation can never happen.
Long term solution should be fixing YARN-4280.
Thoughts?
> Do surgical preemption based on reserved container in CapacityScheduler
> -----------------------------------------------------------------------
>
> Key: YARN-4390
> URL: https://issues.apache.org/jira/browse/YARN-4390
> Project: Hadoop YARN
> Issue Type: Sub-task
> Components: capacity scheduler
> Affects Versions: 3.0.0, 2.8.0, 2.7.3
> Reporter: Eric Payne
> Assignee: Wangda Tan
> Attachments: QueueNotHittingMax.jpg, YARN-4390-design.1.pdf, YARN-4390-test-results.pdf, YARN-4390.1.patch, YARN-4390.2.patch, YARN-4390.3.branch-2.patch, YARN-4390.3.patch, YARN-4390.4.patch, YARN-4390.5.patch, YARN-4390.6.patch, YARN-4390.7.patch, YARN-4390.8.patch
>
>
> There are multiple reasons why preemption could unnecessarily preempt containers. One is that an app could be requesting a large container (say 8-GB), and the preemption monitor could conceivably preempt multiple containers (say 8, 1-GB containers) in order to fill the large container request. These smaller containers would then be rejected by the requesting AM and potentially given right back to the preempted app.
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