The reducers(Fetcher.java) simply ask the Shuffle Service (ShuffleHandler.java) to give them output corresponding to a specific map. The partitioning detail is hidden from the reducers.
Thanks, +Vinod On Mar 9, 2015, at 7:56 AM, xeonmailinglist-gmail <xeonmailingl...@gmail.com> wrote: > Hi, > > I am looking to the Yarn mapreduce internals to try to understand how reduce > tasks know which partition of the map output they should read. Even, when > they re-execute after a crash? > > I am also looking to the mapreduce source code. Is there any class that I > should look to try to understand this question? > > Any help? > > Thanks > > > -- > -- >
