[jira] Commented: (MAPREDUCE-1906) Lower minimum heartbeat interval for tasktracker > Jobtracker

["Todd Lipcon (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/MAPREDUCE-1906?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12973063#action_12973063 ] 

Todd Lipcon commented on MAPREDUCE-1906:
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Perhaps this should be made into a expert-level configurable option? I agree that 3000ms is a bit excessive on a small cluster where the JobTracker is generally "bored" and we've also seen big throughput improvements, especially when users submit jobs with too-small tasks.

> Lower minimum heartbeat interval for tasktracker > Jobtracker
> -------------------------------------------------------------
>
>                 Key: MAPREDUCE-1906
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-1906
>             Project: Hadoop Map/Reduce
>          Issue Type: Improvement
>    Affects Versions: 0.20.1, 0.20.2
>            Reporter: Scott Carey
>         Attachments: MAPREDUCE-1906-0.21.patch
>
>
> I get a 0% to 15% performance increase for smaller clusters by making the heartbeat throttle stop penalizing clusters with less than 300 nodes.
> Between 0.19 and 0.20, the default minimum heartbeat interval increased from 2s to 3s.   If a JobTracker is throttled at 100 heartbeats / sec for large clusters, why should a cluster with 10 nodes be throttled to 3.3 heartbeats per second?  

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