It doesn't. But you really can't do what you're asking. Nor, I think,
would you really want to. The whole idea behind Hadoop is that it's a
distributed system whereby nodes are pretty much interchangeable.
There's nothing to be gained by trying to pin a particular reduce task
to a particular node - and much to be lost: e.g., redundancy,
speculative execution, etc.
DR
On 12/18/2010 01:24 PM, Jane Chen wrote:
But how does this help me request which host to schedule the reduce task to?
Thanks,
Jane
--- On Sat, 12/18/10, Hari Sreekumar<hsreeku...@clickable.com> wrote:
From: Hari Sreekumar<hsreeku...@clickable.com>
Subject: Re: How to Influence Reduce Task Location.
To: mapreduce-user@hadoop.apache.org
Date: Saturday, December 18, 2010, 10:16 AM
Hi Jane,
The partitioner class can be used to achieve this.
(http://hadoop.apache.org/mapreduce/docs/r0.21.0/api/org/apache/hadoop/mapreduce/Partitioner.html).
Thanks,
Hari
On Sat, Dec 18, 2010 at 11:13 PM, Jane Chen<jxchen_us_1...@yahoo.com> wrote:
Hi All,
Is there anyway to influence where a reduce task is run? We have a case where
we'd like to choose the host to run the reduce task based on the task's input
key.
Any suggestion is greatly appreciated.
Thanks,
Jane
