When a Mapper completes, MapCompletionEvents are generated. Reducers try to fetch map outputs for a given map only on the receipt of such events.
Jothi On 5/30/09 10:00 AM, "Jianmin Woo" <[email protected]> wrote: > Hi, > I am being confused by the protocol between mapper and reducer. When mapper > emitting the (key,value) pair done, is there any signal the mapper send out to > hadoop framework in protocol to indicate that map is done and the shuffle/sort > can begin for reducer? If there is no this signal in protocol, when the > framework begin the shuffle/sort? > > Thanks, > Jianmin > > > >
