Home | About | Sematext search-lucene.com search-hadoop.com
 Search Hadoop and all its subprojects:

Switch to Plain View
HDFS, mail # user - Re: reducer tasks start time issue


+
Rishi Yadav 2012-12-22, 16:09
Copy link to this message
-
Re: reducer tasks start time issue
Lin Ma 2012-12-23, 15:09
Thanks Rishi,

My question is answered.

regards,
Lin

On Sun, Dec 23, 2012 at 12:09 AM, Rishi Yadav <[EMAIL PROTECTED]> wrote:

> Hi Lin,
>
> Reduce task starts as soon as output is ready from Mappers. The reduce
> method does not get called until all Mappers are done. If that's not the
> case, all operations which are not commutative and associative will yield
> incorrect result.
>
>
>
> Thanks and Regards,
>
> Rishi Yadav
>
> (o) 408.988.2000x113 ||  (f) 408.716.2726
>
> InfoObjects Inc || http://www.infoobjects.com *(Big Data Solutions)*
>
> *INC 500 Fastest growing company in 2012 || 2011*
>
> *Best Place to work in Bay Area 2012 - *SF Business Times and the Silicon
> Valley / San Jose Business Journal
>
> 2041 Mission College Boulevard, #280 || Santa Clara, CA 95054
>
>
>
>
> On Sat, Dec 22, 2012 at 5:25 AM, Lin Ma <[EMAIL PROTECTED]> wrote:
>
>> Hi guys,
>>
>> Supposing in a Hadoop job, there are both mappers and reducers. My
>> question is, reducer tasks cannot begin until all mapper tasks complete? If
>> so, why designed in this way?
>>
>> thanks in advance,
>> Lin
>>
>
>
+
Harsh J 2012-12-22, 16:15
+
Lin Ma 2012-12-23, 15:09