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https://issues.apache.org/jira/browse/MAPREDUCE-1495?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12833836#action_12833836
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Hemanth Yamijala commented on MAPREDUCE-1495:
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Oh. Sorry. I was thinking you were going to do 1 above and try and modify the
TaskCompletionEvents list. The jobs data structure is ordered for the view
calls which are sorted by JobID (and therefore to some extent by submit time).
The first option seems like a really simple easy fix. Can we attempt that first
and re-run the test.
> Reduce locking contention on JobTracker.getTaskCompletionEvents()
> -----------------------------------------------------------------
>
> Key: MAPREDUCE-1495
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-1495
> Project: Hadoop Map/Reduce
> Issue Type: Improvement
> Affects Versions: 0.20.1
> Reporter: Rajesh Balamohan
>
> While profiling JT for slow performance with small-jobs, it was observed that
> JobTracker.getTaskCompletionEvents() is attributing to 40% of lock contention
> on JT.
> This JIRA ticket is created to explore the possibilities of reducing the
> sychronized code block in this method.
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