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From Ulul <had...@ulul.org>
Subject Re: Question about mapp Task and reducer Task
Date Sun, 15 Feb 2015 12:15:43 GMT

Actually it depends : in MR1 each mapper or reducer will be exezcuted in 
its own JVM, in MR2 you can activate uberjobs that will let the 
framework serialize small jobs' mappers and reducers in the 
applicationmaster JVM.

Look for mapreduce.job.ubertask.* properties


Le 15/02/2015 11:11, bit1129@163.com a écrit :
> Hi, Hadoopers,
> I am pretty newbie to Hadoop, I got a question:  when a job runs, Will 
> each mapper or reducer task take up a JVM process or only a thread?
> I hear that the answer is the Process. That is, say, one job contains 
> 5 mappers and 2 reducers , then there will be 7 JVM processes?
> Thanks.
> ------------------------------------------------------------------------
> bit1129@163.com

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