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From "Devaraj Das (JIRA)" <j...@apache.org>
Subject [jira] Created: (HADOOP-5245) In TaskTracker, the notification for waking up the completion-events fetcher thread may be lost
Date Fri, 13 Feb 2009 04:31:59 GMT
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


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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