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Posted to mapreduce-dev@hadoop.apache.org by "Liyin Liang (Created) (JIRA)" <ji...@apache.org> on 2012/02/22 11:10:49 UTC

[jira] [Created] (MAPREDUCE-3892) runningMapTasks counter is not decremented in case of failed task-cleanup tasks.

runningMapTasks counter is not decremented in case of failed task-cleanup tasks.
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                 Key: MAPREDUCE-3892
                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-3892
             Project: Hadoop Map/Reduce
          Issue Type: Bug
          Components: mrv1
    Affects Versions: 1.0.0
         Environment: Hadoop 1.0.0
            Reporter: Liyin Liang


For a map-only job, a map task has two running attempts: attempt_0 and attempt_1 (speculative task). If attempt_0 completes first, then this map task is complete and attempt_1 is killed. Also a task-cleanup task will be launched to clean attempt_1's output. If the TaskTracker is lost while the task-cleanup task is running, the attempt_1 will remain KILLED_UNCLEAN status. Whats' more runningMapTasks equals one instead of zero after the job is finished.
The incorrect runningMapTasks value can lead to bad scheduling decisions with our scheduler. 

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