[jira] Commented: (MAPREDUCE-2027) fair share scheduler causes unnecessary preemption under some conditions

["Matei Zaharia (JIRA)" <ji...@apache.org>]

    [ 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.