[jira] [Commented] (AURORA-1868) Evaluate multiple preemption proposals per round

["Mehrdad Nurolahzade (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/AURORA-1868?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15803109#comment-15803109 ] 

Mehrdad Nurolahzade commented on AURORA-1868:
---------------------------------------------

https://reviews.apache.org/r/55243/

> Evaluate multiple preemption proposals per round
> ------------------------------------------------
>
>                 Key: AURORA-1868
>                 URL: https://issues.apache.org/jira/browse/AURORA-1868
>             Project: Aurora
>          Issue Type: Story
>          Components: Scheduler
>            Reporter: Mehrdad Nurolahzade
>            Assignee: Mehrdad Nurolahzade
>            Priority: Minor
>
> {{TaskScheduler}} makes an attempt to preempt already identified candidates through {{Preemptor}} when it fails to schedule a task. However, {{Preemptor}} currently evaluates only one candidate per invocation. A candidate may get vetoed at this point by scheduling filters. If a candidate fails validation the task group might get penalized by {{TaskGroups}} to give {{PendingTaskProcessor}} some time to find new preemption candidates; despite the fact that such a candidate may already exist in slotCache. This penalty can result in expiration of {{slotCache}} entries, hence slowing down the overall preemption process.
> Consider modifying {{Preemptor}} so that it evaluates all existing preemption candidates before giving up. This improvement comes at the price of reduced scheduling throughput. However, in a near capacity cluster, reduced scheduling throughput is far more acceptable than failure to schedule critical production services.



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