How can I know how many mappers created?

[谭军 <ta...@163.com>]

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

RE: How can I know how many mappers created?

[Subroto Sanyal <su...@huawei.com>]

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 [mailto:tanjun_2525@163.com] 
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