Hey, Can anyone explain me what is reduce > copy phase in the reducer section ? The (K,List(V)), is passed to the reducer. Is reduce > copy representing copying of K,List(V) on the reducer from all mappers ?
I am monitoring my jobs on the cluster, using Jobtracker url. I am seeing for most of my reducing jobs, something like this : task_201201250352_0001_r_000000 31.05% reduce > copy (395 of 424 at 0.00 MB/s) > 25-Jan-2012 03:54:06 task_201201250352_0001_r_000001 30.73% reduce > copy (391 of 424 at 0.00 MB/s) > 25-Jan-2012 03:54:06 task_201201250352_0001_r_000002 30.89% reduce > copy (393 of 424 at 0.00 MB/s) > 25-Jan-2012 03:54:06 ............................ Can anyone explain me why the speed is 0.00 MB/s. Job is running fine. Is it because this reduce > copy is happening on the same machine. Thanks, Praveenesh
