Reduce starts only after all Map task finishes.Reducers pull data from
mappers ,but processing is done only after all map get finished.
It is better to look into JObtracker UI instead of looking into console.
There you can see only after map 100% Reducer starts
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*Thanks & Regards *
*Unmesha S
You can control when the reduce task even starts in the first place. The
parameter *mapred.reduce.slowstart.completed.maps *
specifies the fraction of the number of maps in the job which should be
complete before reduces are scheduled for the job. So for example if you
set this to .70 then reduce t
The MapReduce-Job contains a shuffle phase, where the intermediary map
outputs are copied to the reducer nodes. This phase of the job is assumed
to be part of the reduce-phase, therefore. the counter already starts
before the map-phase has finished. The actual reduce task will be started,
just
