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Posted to mapreduce-issues@hadoop.apache.org by "Junping Du (JIRA)" <ji...@apache.org> on 2017/01/06 08:09:59 UTC
[jira] [Updated] (MAPREDUCE-6541) Exclude scheduled reducer memory
when calculating available mapper slots from headroom to avoid deadlock
[ https://issues.apache.org/jira/browse/MAPREDUCE-6541?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Junping Du updated MAPREDUCE-6541:
----------------------------------
Fix Version/s: (was: 2.9.0)
> 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
> Fix For: 2.8.0, 3.0.0-alpha2
>
> Attachments: MAPREDUCE-6541.01.patch, MAPREDUCE-6541.02.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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