Hi Sai, The first phase of reducer is to copy/fetch the files from Mapper machine(s) to the reducer. This can be started when some of the mappers have completed. You will notice that the reducer will not surpass 33% though: since the next phase - sort - requries that all of the mappers be completed.
Summary: that is fine. 2013/4/11 Sai Sai <saigr...@yahoo.in> > I am running the wordcount from hadoop-examples, i am giving as input a > bunch of test files, i have noticed in the output given below reduce starts > when the map is at 23%, i was wondering if it is not right that reducers > will start only after the complete mapping is done which mean when map is > 100% then i thought the reducers will start. Why r the reducers starting > when map is still at 23%. > > 13/04/11 21:10:32 INFO mapred.JobClient: map 0% reduce 0% > 13/04/11 21:10:56 INFO mapred.JobClient: map 1% reduce 0% > 13/04/11 21:10:59 INFO mapred.JobClient: map 2% reduce 0% > 13/04/11 21:11:02 INFO mapred.JobClient: map 3% reduce 0% > 13/04/11 21:11:05 INFO mapred.JobClient: map 4% reduce 0% > 13/04/11 21:11:08 INFO mapred.JobClient: map 6% reduce 0% > 13/04/11 21:11:11 INFO mapred.JobClient: map 7% reduce 0% > 13/04/11 21:11:17 INFO mapred.JobClient: map 8% reduce 0% > 13/04/11 21:11:23 INFO mapred.JobClient: map 10% reduce 0% > 13/04/11 21:11:26 INFO mapred.JobClient: map 12% reduce 0% > 13/04/11 21:11:32 INFO mapred.JobClient: map 14% reduce 0% > 13/04/11 21:11:44 INFO mapred.JobClient: map 23% reduce 0% > 13/04/11 21:11:50 INFO mapred.JobClient: map 23% reduce 1% > 13/04/11 21:11:53 INFO mapred.JobClient: map 33% reduce 7% > 13/04/11 21:12:02 INFO mapred.JobClient: map 42% reduce 7% > > Please pour some light. > Thanks > Sai >
