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https://issues.apache.org/jira/browse/YARN-8833?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16687606#comment-16687606
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ASF GitHub Bot commented on YARN-8833:
--------------------------------------
GitHub user yoelee opened a pull request:
https://github.com/apache/hadoop/pull/439
YARN-8833 fix compute shares may lock the scheduling process
When compute fair share, there may be a chance triggering the problem of
Integer overflow, and entering an infinite loop, which blocks the scheduling
process.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/yoelee/hadoop trunk
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/hadoop/pull/439.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #439
----
commit 39a6f7cab193be910bfb34265ceb696ddbd78da5
Author: liyakun.hit <liyakun.hit@...>
Date: 2018-11-15T07:28:34Z
YARN-8833 fix compute shares may lock the scheduling process
----
> compute shares may lock the scheduling process
> -----------------------------------------------
>
> Key: YARN-8833
> URL: https://issues.apache.org/jira/browse/YARN-8833
> Project: Hadoop YARN
> Issue Type: Bug
> Components: fairscheduler
> Reporter: liyakun
> Assignee: liyakun
> Priority: Major
>
> When use w2rRatio compute fair share, there may be a chance triggering the
> problem of Int overflow, and entering an infinite loop.
> Since the compute share thread holds the writeLock, it may blocking
> scheduling thread.
> This issue occurs in a production environment with 8500 nodes. And we have
> already fixed it.
>
> added 2018-10-29: elaborate the problem
> /**
> * Compute the resources that would be used given a weight-to-resource ratio
> * w2rRatio, for use in the computeFairShares algorithm as described in #
> */
> private static int resourceUsedWithWeightToResourceRatio(double w2rRatio,
> Collection<? extends Schedulable> schedulables, String type) {
> int resourcesTaken = 0;
> for (Schedulable sched : schedulables) \{ int share = computeShare(sched,
> w2rRatio, type); resourcesTaken += share; }
> return resourcesTaken;
> }
> The variable resourcesTaken is an integer type. And it also is accumulated
> value of result of
> computeShare(Schedulable sched, double w2rRatio,String type) which is a value
> between the min share and max share of a queue.
> For example, when there are 3 queues, each has min share = max share =
> Integer.MAX_VALUE, the resourcesTaken will be out of Integer bound, and it
> will be a negative number.
> when resourceUsedWithWeightToResourceRatio(double w2rRatio, Collection<?
> extends Schedulable> schedulables, String type) return a negative number, the
> loop in
> computeSharesInternal() may never out which got the scheduler lock.
>
> //org.apache.hadoop.yarn.server.resourcemanager.scheduler.fair.policies.ComputeFairShares
> while (resourceUsedWithWeightToResourceRatio(rMax, schedulables, type)
> < totalResource){
> rMax *= 2.0;
> }
> This may blocking scheduling thread.
>
>
>
>
>
>
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