Amazon Elastic MapReduce: the number of launched map task

Posted by S.N on Stack Overflow See other posts from Stack Overflow or by S.N
Published on 2010-05-12T19:14:09Z Indexed on 2010/05/14 13:44 UTC
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mapreduce

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Hi,

In the "syslog" for a MapReduce job flow step, I see the following:

Job Counters
  Launched reduce tasks=4
  Launched map tasks=39

Does the number of launched map tasks include failed tasks?

I am using NLineInputFormat class as input format to manage the number of map tasks. However, I get slightly different numbers for exact same input occasionally, or depending on the number of instances (10, 15, and 20).

Can anyone tell me why I am seeing different number of tasks launched?

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