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https://issues.apache.org/jira/browse/YARN-6210?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15879463#comment-15879463
 ] 

Daniel Templeton commented on YARN-6210:
----------------------------------------

You're gonna love me for this one...

We now have:
{code}
    if (!starved) {
      lastTimeAtFairShare = now;
    }

    if (!starved ||
        now - lastTimeAtFairShare < fsQueue.getFairSharePreemptionTimeout()) {
      fairshareStarvation = Resources.none();
    } 
{code}

What about:

{code}
    if (!starved ||
        now - lastTimeAtFairShare < fsQueue.getFairSharePreemptionTimeout()) {
      if (!starved) {
        lastTimeAtFairShare = now;
      }

      fairshareStarvation = Resources.none();
    } 
{code}

?

> FS: Node reservations can interfere with preemption
> ---------------------------------------------------
>
>                 Key: YARN-6210
>                 URL: https://issues.apache.org/jira/browse/YARN-6210
>             Project: Hadoop YARN
>          Issue Type: Bug
>          Components: fairscheduler
>    Affects Versions: 2.9.0
>            Reporter: Karthik Kambatla
>            Assignee: Karthik Kambatla
>         Attachments: YARN-6210.1.patch, YARN-6210.2.patch, YARN-6210.3.patch, 
> YARN-6210.4.patch
>
>
> Today, on a saturated cluster, apps with pending demand reserve nodes. A new 
> app might not be able to preempt resources because these nodes are already 
> reserved. This can be reproduced by the example in YARN-6151. 
> Since node reservations are to prevent starvation of apps requesting large 
> containers, triggering these reservations only on starved applications would 
> avoid this situation. 



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