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From "Hemanth Yamijala (JIRA)" <j...@apache.org>
Subject [jira] Commented: (MAPREDUCE-1495) Reduce locking contention on JobTracker.getTaskCompletionEvents()
Date Mon, 15 Feb 2010 15:21:27 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-1495?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12833836#action_12833836
] 

Hemanth Yamijala commented on MAPREDUCE-1495:
---------------------------------------------

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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