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From "Amar Kamat (JIRA)" <j...@apache.org>
Subject [jira] Commented: (MAPREDUCE-1533) Reduce or remove usage of String.format() usage in CapacityTaskScheduler.updateQSIObjects and Counters.makeEscapedString()
Date Mon, 10 May 2010 08:41:50 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-1533?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12865703#action_12865703
] 

Amar Kamat commented on MAPREDUCE-1533:
---------------------------------------

bq. JobTracker.checkMemoryRequirements has a debug log without checking for isDebugEnabled().
Though it is not under JobTracker's heartbeat path, it is holding JobTracker lock for the
debug log.

bq. found a couple of unprotected debug logs statements in JobInProgress also.

The main aim of this jira was to fix few performance bottlenecks in the heartbeat processing.
Maybe we can fix these bugs/improvements in a separate jira?

> 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: Amar Kamat
>         Attachments: 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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