[
https://issues.apache.org/jira/browse/MAPREDUCE-2905?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13125843#comment-13125843
]
Harsh J commented on MAPREDUCE-2905:
------------------------------------
Jeff,
I'll leave the final review to people better suited to reviewing FairScheduler
patches, but am gonna post some notes on getting this patch to an acceptable
state:
A few nits, hence:
- Patch is mixing spaces and tabs. Follow the coding guidelines and use only
spaces. 2 spaces per indent instead of hard tab characters which seem present
right now.
- If you'd like to get this included upstream, you'll have to re-up the patch
with permission grants to ASF. This is doable when you attach a file (look for
an option at the bottom -- or perhaps you missed it accidentally).
If possible, can we somehow have a test for this? Just asking.
> CapBasedLoadManager incorrectly allows assignment when assignMultiple is true
> (was: assignmultiple per job)
> -----------------------------------------------------------------------------------------------------------
>
> Key: MAPREDUCE-2905
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-2905
> Project: Hadoop Map/Reduce
> Issue Type: Improvement
> Components: contrib/fair-share
> Affects Versions: 0.20.2
> Reporter: Jeff Bean
> Attachments: MR-2905.patch
>
>
> We encountered a situation where in the same cluster, large jobs benefit from
> mapred.fairscheduler.assignmultiple, but small jobs with small numbers of
> mappers do not: the mappers all clump to fully occupy just a few nodes, which
> causes those nodes to saturate and bottleneck. The desired behavior is to
> spread the job across more nodes so that a relatively small job doesn't
> saturate any node in the cluster.
> Testing has shown that setting mapred.fairscheduler.assignmultiple to false
> gives the desired behavior for small jobs, but is unnecessary for large jobs.
> However, since this is a cluster-wide setting, we can't properly tune.
> It'd be nice if jobs can set a param similar to
> mapred.fairscheduler.assignmultiple on submission to better control the task
> distribution of a particular job.
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators:
https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira
