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From Harsh J <ha...@cloudera.com>
Subject Re: Running map tasks after all reduces have finished
Date Thu, 23 Aug 2012 10:08:20 GMT
Hey Jan,

What version/distribution of Hadoop are you noticing this on?

On Thu, Aug 23, 2012 at 2:55 PM, Jan Lukavsk√Ĺ
<jan.lukavsky@firma.seznam.cz> wrote:
> Hi all,
>
> we are seeing strange behaviour of JobTracker in the following scenario:
>  - job finishes map phase and starts reduce
>  - after the shuffle phase of all reducers we loose a tasktracker, that
> doesn't run any reducer - so all remaining reducers are still running in the
> reduce phase
>  - map tasks that were running on the lost tasktracker are rescheduled
>  - reduces may finish earlier than the rescheduled map tasks and so the job
> is blocked waiting for the maps to finish, although their output is simple
> discarded
>
> Is this behaviour a bug or feature? :) I haven't found any JIRA that would
> describe it, if there exists one can anyone point me out?
>
> Thanks,
>  Jan
>



-- 
Harsh J

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