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From Bertrand Dechoux <decho...@gmail.com>
Subject Re: knowing the nodes on which reduce tasks will run
Date Mon, 03 Sep 2012 15:24:26 GMT

The reducer is run where there is slot available, the location is not
related to where the data is located and it is not possible to choose where
the reducer will run (except by tweaking the tasktracker...).



On Mon, Sep 3, 2012 at 4:19 PM, Abhay Ratnaparkhi <
abhay.ratnaparkhi@gmail.com> wrote:

> Hello,
> How can one get to know the nodes on which reduce tasks will run?
> One of my job is running and it's completing all the map tasks.
> My map tasks write lots of intermediate data. The intermediate directory
> is getting full on all the nodes.
> If the reduce task take any node from cluster then It'll try to copy the
> data to same disk and it'll eventually fail due to Disk space related
> exceptions.
> I have added few more tasktracker nodes in the cluster and now want to run
> reducer on new nodes only.
> Is it possible to choose a node on which the reducer will run? What's the
> algorithm hadoop uses to get a new node to run reducer?
> Thanks in advance.
> Bye
> Abhay

Bertrand Dechoux

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