In TaskTracker, the notification for waking up the completion-events fetcher
thread may be lost
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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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