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https://issues.apache.org/jira/browse/YARN-6021?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15771642#comment-15771642
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Feng Yuan commented on YARN-6021:
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Perhaps I was not clear,if R value is some very wee like 0.00390625,when a queue
is 0 minshare(not configed in fair-scheduler.xml) and weight 1 by default.
Its fairshare formula is (int)Max(R*weight,minShare) will equal to 0.
And this queue is nerver get preempt forever,This is serious.
As i think,minshare configation is uncontrollable by now,There is no check
in now code if exceed Total.
But if base on above situation,if this happened,some 0 minshare queue will
suffer.
So i suggestion wipe off minshare when compute fairshare.
Thanks.
> When your allocated minShare of all queue`s added up exceed cluster capacity
> you can get some queue for 0 fairshare
> -------------------------------------------------------------------------------------------------------------------
>
> Key: YARN-6021
> URL: https://issues.apache.org/jira/browse/YARN-6021
> Project: Hadoop YARN
> Issue Type: Bug
> Components: fairscheduler
> Affects Versions: 2.4.0
> Reporter: Feng Yuan
> Priority: Critical
>
> In fair-scheduler.xml,If you config the minshare add up exceed parentQueue`s
> fairshare,for root`s childs,fairshare is cluster capacity.
> You will found your R value look like below when compute childs fairshares:
> 1.0
> 0.5
> 0.25
> 0.125
> 0.0625
> 0.03125
> 0.015625
> 0.0078125
> 0.00390625
> I find this is due to:
> double rMax = 1.0;
> while (resourceUsedWithWeightToResourceRatio(rMax, schedulables, type)
> < totalResource) {
> rMax *= 2.0;
> }
> because resourceUsedWithWeightToResourceRatio will add minShare together.
> As i think is really should we bring in minShare when compute fairshare?
> My advice is we just consider weight is enough,and minshare's guarantee
> will get fulfill when assginContainer!
> Hope suggestion!
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