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From Chandraprakash Bhagtani <cpbhagt...@gmail.com>
Subject Re: Why I can only run 2 map/reduce task at a time?
Date Mon, 21 Dec 2009 06:41:23 GMT
You can increase the map/reduce slots
using "mapred.tasktracker.map(reduce).tasks.maximum"  property only

there can be following cases

1. your changes are not taking effect. you need to restart the cluster after
making changes in conf xml.
    you can check your cluster (Map/Reduce) capacity at

2. your data is not enough to create more than 2 map tasks. But in that case
reducers should still be equal
    to mapred.reduce.tasks

On Mon, Dec 21, 2009 at 9:39 AM, Starry SHI <starrysl@gmail.com> wrote:

> Hi,
> I am currently using hadoop 0.19.2 to run large data processing. But I
> noticed when the job is launched, there are only two map/reduce tasks
> running in the very beginning. after one heartbeat (5sec), another two
> map/reduce task is started. I want to ask how I can increase the map/reduce
> slots?
> In the configuration file, I have already set
> "mapred.tasktracker.map(reduce).tasks.maximum" to 10, and
> "mapred.map(reduce).tasks" to 10. But there are still only 2 are launched.
> Eager to hear from your solutions!
> Best regards,
> Starry
> /* Tomorrow is another day. So is today. */

Thanks & Regards,
Chandra Prakash Bhagtani,
Impetus Infotech (india) Pvt Ltd.

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