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From "Gautam Kowshik (JIRA)" <j...@apache.org>
Subject [jira] Created: (HADOOP-5949) JobTracker should give preference to failed tasks over virgin tasks so as to terminate the job ASAP if it is eventually going to fail.
Date Mon, 01 Jun 2009 12:54:07 GMT
JobTracker should give preference to failed tasks over virgin tasks so as to terminate the
job ASAP if it is eventually going to fail. 
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                 Key: HADOOP-5949
                 URL: https://issues.apache.org/jira/browse/HADOOP-5949
             Project: Hadoop Core
          Issue Type: Improvement
          Components: mapred
            Reporter: Gautam Kowshik
            Assignee: Devaraj Das


Case in point... I have 1585 maps and 160 slots (40 nodes). The job is such that all maps
fail within 2-3 minutes. The job takes forever to realise that the job is bad. It took 2526
failures for it to reach 4 failed attempts for a task. 

As I understand, currently the JT prefers a failed task if and only if a task tracker with
a split replica for that map came asking for a task. In fact there may not be a single TT
at all in the mapred cluster which has a replica for the splits used in this job (pre-0.20).
This delays the job failure by a lot and hence degrades cluster utilization as a whole. If
i'm on a shared cluster with many jobs waiting on it to fail, it's bad. 

The JT should prefer a failed task a lot earlier than waiting for a data local TT to come
around asking. 

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