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HDFS, mail # user - Re: Increase the number of mappers in PM mode


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Re: Increase the number of mappers in PM mode
yypvsxf19870706 2013-03-16, 04:46
hi:
   i think i have got it . Thank you.

发自我的 iPhone

在 2013-3-15,18:32,Zheyi RONG <[EMAIL PROTECTED]> 写道:

> Indeed you cannot explicitly set the number of mappers, but still you can gain some control over it, by setting mapred.max.split.size, or mapred.min.split.size.
>
> For example, if you have a file of 10GB (10737418240 B), you would like 10 mappers, then each mapper has to deal with 1GB data.
> According to "splitsize = max(minimumSize, min(maximumSize, blockSize))", you can set mapred.min.split.size=1073741824 (1GB), i.e.    
> $hadoop jar -Dmapred.min.split.size=1073741824 yourjar yourargs
>
> It is well explained in thread: http://stackoverflow.com/questions/9678180/change-file-split-size-in-hadoop.
>
> Regards,
> Zheyi.
>
> On Fri, Mar 15, 2013 at 8:49 AM, YouPeng Yang <[EMAIL PROTECTED]> wrote:
>> s
>
>