Even though reduces are scheduled, they just transfer data from maps before all maps are completed.The reduce only begins its processing when all maps are completed.
Please correct me if I'm wrong. regards, 2009/8/2 我的Gmail邮箱 <zhangxiang...@gmail.com> > Hi, everyone. > In class org.apache.hadoop.mapred.JobInProgress, there is a public method: > scheduleReduces(), it will return true if "finishedMapTasks >= > completedMapsForReduceSlowstart" > and then the scheduler can schedule a new reduce task for a given > taskTracker. > > but as I konw, reduce can not be started unitl map is 100% completed. Does > anyone can explain it? thanks a lot. > -- Ahmad Humayun Research Associate Computer Science Dpt., LUMS http://suraj.lums.edu.pk/~ahmadh +92 321 4457315
