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https://issues.apache.org/jira/browse/MAPREDUCE-6541?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15425755#comment-15425755
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Hadoop QA commented on MAPREDUCE-6541:
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| (x) *{color:red}-1 overall{color}* |
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|| Vote || Subsystem || Runtime || Comment ||
| {color:blue}0{color} | {color:blue} reexec {color} | {color:blue} 0m 0s
{color} | {color:blue} Docker mode activated. {color} |
| {color:red}-1{color} | {color:red} patch {color} | {color:red} 0m 6s {color}
| {color:red} MAPREDUCE-6541 does not apply to trunk. Rebase required? Wrong
Branch? See https://wiki.apache.org/hadoop/HowToContribute for help. {color} |
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|| Subsystem || Report/Notes ||
| JIRA Patch URL |
https://issues.apache.org/jira/secure/attachment/12771973/MAPREDUCE-6541.01.patch
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| JIRA Issue | MAPREDUCE-6541 |
| Console output |
https://builds.apache.org/job/PreCommit-MAPREDUCE-Build/6676/console |
| Powered by | Apache Yetus 0.3.0 http://yetus.apache.org |
This message was automatically generated.
> Exclude scheduled reducer memory when calculating available mapper slots from
> headroom to avoid deadlock
> ---------------------------------------------------------------------------------------------------------
>
> Key: MAPREDUCE-6541
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-6541
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Affects Versions: 2.7.1
> Reporter: Wangda Tan
> Assignee: Varun Saxena
> Attachments: MAPREDUCE-6541.01.patch
>
>
> We saw a MR deadlock recently:
> - When NM restarted by framework without enable recovery, containers running
> on these nodes will be identified as "ABORTED", and MR AM will try to
> reschedule "ABORTED" mapper containers.
> - Since such lost mappers are "ABORTED" container, MR AM gives normal mapper
> priority (priority=20) to such mapper requests. If there's any pending
> reducer (priority=10) at the same time, mapper requests need to wait for
> reducer requests satisfied.
> - In our test, one mapper needs 700+ MB, reducer needs 1000+ MB, and RM
> available resource = mapper-request = (700+ MB), only one job was running in
> the system so scheduler cannot allocate more reducer containers AND MR-AM
> thinks there're enough headroom for mapper so reducer containers will not be
> preempted.
> MAPREDUCE-6302 can solve most of the problems, but in the other hand, I think
> we may need to exclude scheduled reducers resource when calculating
> #available-mapper-slots from headroom. Which we can avoid excessive reducer
> preemption.
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