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https://issues.apache.org/jira/browse/HADOOP-5245?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Devaraj Das updated HADOOP-5245:
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Attachment: 5245.patch
Straightforward patch.
> In TaskTracker, the notification for waking up the completion-events fetcher
> thread may be lost
> -----------------------------------------------------------------------------------------------
>
> Key: HADOOP-5245
> URL: https://issues.apache.org/jira/browse/HADOOP-5245
> Project: Hadoop Core
> Issue Type: Bug
> Components: mapred
> Reporter: Devaraj Das
> Assignee: Devaraj Das
> Fix For: 0.21.0
>
> Attachments: 5245.patch
>
>
> In the TaskTracker, there is a completion events fetcher thread that fetches
> new events from the JobTracker. Normally, the fetcher thread would sleep for
> heartbeatInterval amount of time per cycle. When a reduce task asks for
> completion events from the corresponding TaskTracker and the TaskTracker
> currently doesn't have anything to hand out, a notification is sent to the
> completion events fetcher thread to wake up and fetch new events if any.
> Sometimes this notification could be lost and the reduce task would be idle
> for a few seconds. This hurts the performance of jobs like terasort.
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