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