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MapReduce, mail # user - Reduce Task Priority / Scheduler


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Re: Reduce Task Priority / Scheduler
David Rosenstrauch 2010-12-20, 03:32
On 12/19/2010 10:39 AM, Martin Becker wrote:
> Hello everybody,
>
> is there a possibility to make sure that certain/all reduce tasks,
> i.e. the reducers to certain keys, are executed in a specified order?
> This is Job internal, so the Job Scheduler is probably the wrong place to start?
> Does the order induced by the Comparable interface influence the
> execution order at all?
>
> Thanks in advance,
> Martin

Not that I know of.  And again, this kind of defeats the whole purpose
of Hadoop.  The whole idea is that tasks are executed asynchronously /
in parallel.  What you're asking for is to execute tasks synchronously
and in sequence.

DR