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https://issues.apache.org/jira/browse/MAPREDUCE-1495?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12833830#action_12833830
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Hemanth Yamijala commented on MAPREDUCE-1495:
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bq. Will try to check the possibility of using ConcurrentHashMap as it can
drastically minimize the requirement of synchronized (and by default it
supports 16 concurrent threads).
Can you elaborate please ? The current data structure is a simple list. How are
you modifying this to a map ? Also, I think the ordering of events is important.
> 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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