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From "Hemanth Yamijala (JIRA)" <j...@apache.org>
Subject [jira] Commented: (MAPREDUCE-1533) reduce or remove usage of String.format() usage in CapacityTaskScheduler.updateQSIObjects
Date Tue, 06 Apr 2010 10:01:34 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-1533?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12853832#action_12853832
] 

Hemanth Yamijala commented on MAPREDUCE-1533:
---------------------------------------------

bq. As of now its a push model where every change in the scheduler's state results into an
info string which gets pushed to all the jobs. Shouldn't it be a pull model wherein the jobs
pull the data from the scheduler whenever required?

Yes, this seems a sensible direction to me. Given that the view requests come very infrequently
as compared to heartbeats, this is a more optimal design.

bq. But for now we can keep it simple and solve the problem at hand by using StringBuilder.
Thoughts?

I am fine with this proposal.

> reduce or remove usage of String.format() usage in CapacityTaskScheduler.updateQSIObjects
> -----------------------------------------------------------------------------------------
>
>                 Key: MAPREDUCE-1533
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-1533
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>    Affects Versions: 0.20.1
>            Reporter: Rajesh Balamohan
>            Assignee: Amar Kamat
>         Attachments: mapreduce-1533-v1.4.patch
>
>
> When short jobs are executed in hadoop with OutOfBandHeardBeat=true, JT executes heartBeat()
method heavily. This internally makes a call to CapacityTaskScheduler.updateQSIObjects().

> CapacityTaskScheduler.updateQSIObjects(), internally calls String.format() for setting
the job scheduling information. Based on the datastructure size of "jobQueuesManager" and
"queueInfoMap", the number of times String.format() gets executed becomes very high. String.format()
internally does pattern matching which turns to be out very heavy (This was revealed while
profiling JT. Almost 57% of time was spent in CapacityScheduler.assignTasks(), out of which
String.format() took 46%.
> Would it be possible to do String.format() only at the time of invoking JobInProgress.getSchedulingInfo?.
This might reduce the pressure on JT while processing heartbeats. 

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