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Posted to common-user@hadoop.apache.org by Shi Yu <sh...@uchicago.edu> on 2011/12/13 05:45:49 UTC

Create a single output per each mapper

Hi,

Suppose I have two mappers, each mapper is assigned 10 lines of 
data. I want to set a counter for each mapper, counting and 
accumulating, then output the counter value to the reducer when 
the mapper finishes processing all the assigned lines.  So I 
want the mapper outputs values only when there is no further 
incoming data (when that mapper closes). Is this doable? How? 
thanks!

Shi

Re: Create a single output per each mapper

Posted by Prashant Kommireddi <pr...@gmail.com>.
Take a look at cleanup() method on Mapper.

Thanks,
Prashant

Sent from my iPhone

On Dec 12, 2011, at 8:46 PM, Shi Yu <sh...@uchicago.edu> wrote:

> Hi,
>
> Suppose I have two mappers, each mapper is assigned 10 lines of
> data. I want to set a counter for each mapper, counting and
> accumulating, then output the counter value to the reducer when
> the mapper finishes processing all the assigned lines.  So I
> want the mapper outputs values only when there is no further
> incoming data (when that mapper closes). Is this doable? How?
> thanks!
>
> Shi