Could you please explain where the Reduce class will be executed ? Master node or Salve node? How about if I configure multiple reducers ?



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Could you please explain where the Reduce class will be executed ? Master node or Salve node? How about if I configure multiple reducers ? 


2 Answer(s)


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Hi Satya,

The TaskTracker executes the Mapper/ Reducer task as a child process in a separate jvm and Tasktracker is part of Slavesnodes/Workernodes.

You could generate N MapReduce applications in the same java project, and then you re-use the Map, and develop N reducers.

In job.setReducerClass in each main class you set each Reducer. The Map will be the same.

Hope this helps.

Thanks.

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Hi Abhijit,

Thanks for the time and explanation. If Reducer is running on TaskTracker in the salvenodes then when we are using multiple partitions (obviously multiple reducers) then how and where the result will be combined between the salvesnodes/workernodes?

Could you please explain more in detailed. If any document is available on this please share with me. Thanks in advance.

Best Regards,

Satya Garapati