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From "Liyin Liang (JIRA)" <j...@apache.org>
Subject [jira] Commented: (MAPREDUCE-1533) Reduce or remove usage of String.format() usage in CapacityTaskScheduler.updateQSIObjects and Counters.makeEscapedString()
Date Tue, 31 Aug 2010 12:10:54 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-1533?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12904607#action_12904607
] 

Liyin Liang commented on MAPREDUCE-1533:
----------------------------------------

The patch has a small problem.
I think line257-259 of Counters.java should be:
for(String subcounter: subcountersArray) {
  builder.append(subcounter);
}

instead of:
for(Counter counter: subcounters.values()) {
  builder.append(counter.makeEscapedCompactString());
}

> Reduce or remove usage of String.format() usage in CapacityTaskScheduler.updateQSIObjects
and Counters.makeEscapedString()
> --------------------------------------------------------------------------------------------------------------------------
>
>                 Key: MAPREDUCE-1533
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-1533
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>          Components: jobtracker
>    Affects Versions: 0.20.1
>            Reporter: Rajesh Balamohan
>            Assignee: Dick King
>             Fix For: 0.22.0
>
>         Attachments: mapreduce-1533--2010-05-10a.patch, mapreduce-1533--2010-05-21.patch,
mapreduce-1533--2010-05-21a.patch, mapreduce-1533--2010-05-24.patch, MAPREDUCE-1533-and-others-20100413.1.txt,
MAPREDUCE-1533-and-others-20100413.bugfix.txt, mapreduce-1533-v1.4.patch, mapreduce-1533-v1.8.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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