[jira] [Comment Edited] (YARN-2009) Priority support for preemption in ProportionalCapacityPreemptionPolicy

["Sunil G (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/YARN-2009?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15522161#comment-15522161 ] 

Sunil G edited comment on YARN-2009 at 9/26/16 9:19 AM:
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Thanks [~eepayne] for the detailed explanation. 

bq.when it comes time for the intra-queue preemption policy to preempt resources, it seems to me that the policy won't preempt enough resources.
Yes. I was also thinking on same line. If {{tq.used}} is less than {{tq.guaranteed}}, then we may hit less preemption if we use  {{tq.guaranteed}}. Since *used* is less than *guaranteed*, there are enough resources available for this queue. So high priority apps will automatically get those resources by scheduler. 
But after thinking more, there is one case. Adding to the above mentioned scenario ({{tq.used}} is less than {{tq.guaranteed}}), assume another queue was over-utilizing resource, so current queue has to wait till inter-queue preemption to kick in (to get *guaranteed - used*). If inter-queue preemption is turned off, then current queue may not get those resources immediately. In such cases, I think we need to use  {{tq.used}}. I would like hear thoughts on this point. [~eepayne] and [~leftnoteasy]. pls share your thoughts.


was (Author: sunilg):
Thanks [~eepayne] for the detailed explanation. 

bq.when it comes time for the intra-queue preemption policy to preempt resources, it seems to me that the policy won't preempt enough resources.
Yes. I was also thinking on same line. If {{tq.used}} is less than {{tq.guaranteed}}, then we may hit less preemption if we use  {{tq.guaranteed}}. Since *used* is less that *guaranteed*, there are enough resources for this queue. So high priority apps will automatically gets those resources by scheduler. 
But after thinking more, there is one scenario. Adding to the same scenario, assume another queue was over-utilizing resource, so current queue has to wait till inter-queue preemption to kick in. (If inter-queue preemption is turned off, then current queue may not get those resources immediately. In such cases, I think we need to use  {{tq.used}}. I would like hear thoughts on this point. [~eepayne] and [~leftnoteasy]. pls share your thoughts.

> Priority support for preemption in ProportionalCapacityPreemptionPolicy
> -----------------------------------------------------------------------
>
>                 Key: YARN-2009
>                 URL: https://issues.apache.org/jira/browse/YARN-2009
>             Project: Hadoop YARN
>          Issue Type: Sub-task
>          Components: capacityscheduler
>            Reporter: Devaraj K
>            Assignee: Sunil G
>         Attachments: YARN-2009.0001.patch, YARN-2009.0002.patch
>
>
> While preempting containers based on the queue ideal assignment, we may need to consider preempting the low priority application containers first.



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