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From "Murali Krishna. P" <muralikpb...@yahoo.com>
Subject Hadoop starting extra map tasks and eventually failing
Date Fri, 15 Oct 2010 11:41:19 GMT
    I have attached the relevant part of jobtracker log. The job1 had 3 splits, 
but it started 5 map tasks, m_00000 through m_00004. ( I have the speculative 
execution turned off). The job some how succededs, the log files for 4th and 5th 
task didnt get any records. Hovewer the next job again has 3 splits but this 
time it schedules only m_00003 m_00004 and both of them fail. There is no 
userlogs created for these 2 tasks. The tasktracker log mentions that the jvm 
has spawned and exited immediately. And it doesnot schedule the first 3 map 
tasks and the job fails since 4th and 5th task fail even after retries.

Why is extra tasks gettin scheduled ?
How did those tasks pass in the first case?
Why the right tasks are not scheduled in the second job?

This is easily reproducible, please take a look at JT log and advise. 

Murali Krishna

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