[
https://issues.apache.org/jira/browse/MAPREDUCE-2027?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12902017#action_12902017
]
Matei Zaharia commented on MAPREDUCE-2027:
------------------------------------------
Some of this could be specific to Facebook, because I believe you guys have
patched in LATE speculation (HADOOP-2141) onto your Hadoop 0.20, but may not
have updated the scheduler bits that count speculative tasks. However, it's
also possible that this issue remains in trunk.
> fair share scheduler causes unnecessary preemption under some conditions
> ------------------------------------------------------------------------
>
> Key: MAPREDUCE-2027
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-2027
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Components: contrib/fair-share
> Reporter: Joydeep Sen Sarma
>
> When the cluster hits speculative cap - JobInProgress does not speculate any
> more. however FairShare Scheduler continues to believe that tasks need to be
> speculated.
> Under such conditions, FS Scheduler will start preempting repeatedly (because
> from it's perspective - certain jobs are not getting the slots they deserve
> (for speculative tasks)).
> There may be other reasons for excessive preemption as well - this one stood
> out clearly.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
