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From "Arun C Murthy (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-1900) the heartbeat and task event queries interval should be set dynamically by the JobTracker
Date Thu, 18 Oct 2007 10:40:50 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-1900?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12535879

Arun C Murthy commented on HADOOP-1900:

bq. I wonder if instead we should just make it clusterSize/50+1? That way, small clusters
will get a heartbeat of just one second, which should make them more responsive.


I'd like to see some numbers about how long it takes to process a heartbeat etc. before we
decide on the actual scaling factors (both up and down). Given that we've run so far on clusters
of 2000 nodes with heartbeat-interval of 10s, I'd suspect scaling it up by 10s for every 500
nodes is too conservative... anyway I'll believe the numbers when we have them.

Also, while we are at this, I say we should start to consider *busy-ness* of JobTracker too,
along with the cluster-size. So, for e.g., if the individual tasks are taking in the order
of minutes, then it might not matter much if we send one every 20s or so, in some cases it
might. I know that the sort's map tasks take around 40s each... 

So, one way to take this into account might be to maintain an average time-to-complete for
all tasks in the system (of current jobs) and factor that into the scaling of the intervals.

> the heartbeat and task event queries interval should be set dynamically by the JobTracker
> -----------------------------------------------------------------------------------------
>                 Key: HADOOP-1900
>                 URL: https://issues.apache.org/jira/browse/HADOOP-1900
>             Project: Hadoop
>          Issue Type: Improvement
>          Components: mapred
>            Reporter: Owen O'Malley
>            Assignee: Amareshwari Sri Ramadasu
> The JobTracker should scale the intervals that the TaskTrackers use to contact it dynamically,
based on how the busy it is and the size of the cluster.

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