FAQ
Hi Subroto,
Thank you very much!

2011-08-08



tanjun_2525



发件人: Subroto Sanyal <subrotosanyal@huawei.com>
发送时间: 2011-08-08 12:33
主 题: RE: How can I know how many mappers created?
收件人: mapreduce-user@hadoop.apache.org



Hi Jun,

Request you to go through this link:
http://wiki.apache.org/hadoop/HowManyMapsAndReduces

Following configuration may help you :
mapred.min.split.size
mapred.map.tasks (This is just a hint to InputFormat)

But how can I know how many mappers have been created while doing my job?
The implementation of InputFormat actually defines how many Mappers are going to be in the submitted job.

Can I do some sets to make it only 2 mappers created and each mapper runs on one node?
The scheduler implementation has the logic to schedule mappers and reducers.



Regards,
Subroto Sanyal



From: 谭军
Sent: Sunday, August 07, 2011 12:15 PM
To: mapreduce-user@hadoop.apache.org
Subject: How can I know how many mappers created?

Hi,
I just want 2 mappers created to do my job for there are only 2 data nodes.
I think that is the most efficient.
But how can I know how many mappers have been created while doing my job?
Can I do some sets to make it only 2 mappers created and each mapper runs on one node?
Thanks


--
Best regards!
Jun Tan

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