These extra tasks are job-setup and job-cleanup tasks which use map/reduce 
slots to run.
Looks like job-setup task failed for your second job even after retries, so no 
maps are scheduled. But you should see tasklogs for the failed tasks.

Thanks
Amareshwari

On 10/15/10 5:11 PM, "Murali Krishna. P" <[email protected]> wrote:

Hi,
    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.

Thanks,
Murali Krishna


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