Details
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Bug
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Status: Resolved
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Major
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Resolution: Won't Fix
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2.0.2-alpha
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None
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None
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CDH4.1.2 MR1
Description
We have a M/R job that use Mapper + Combiner but have nothing to do in Reducer :
Bulk indexing of HBase data in ElasticSearch,
Map output is K / V : #bulk / json_data_to_be_indexed.
So job is launched maps work, combiners index and a reducer is created for nothing (sometimes waiting for other M/R job to free a tasktracker slot for reducer cf. MAPREDUCE-5019 )
When we put ```job.setNumReduceTasks(0);``` in our job .run(), mapper are started but combiner are not used.