No you cannot raise this event yourself, this event is generated internally by the framework.
I am guessing that what you probably want is to have a chain of MapReduce Jobs where the output of one is automatically fed as input to another. You can look at these classes: JobControl and ChainMapper/ChainReducer. Jothi On 6/1/09 11:00 AM, "Jianmin Woo" <jianmin_...@yahoo.com> wrote: > Thanks a lot for your explanation, Jothi. > > So is this event generated by hadoop framework? Is there any API in mapper to > fire this event? Actually, I am thinking to implement a mapper that will emit > some <key, value> pairs, then fire this event to let the reducer works, the > same mapper task then emit some other <key, value> pairs and repeat. Do you > think is this logic feasible by current API? > > Thanks, > Jianmin > > > > > > ________________________________ > From: Jothi Padmanabhan <joth...@yahoo-inc.com> > To: core-user@hadoop.apache.org > Sent: Monday, June 1, 2009 12:26:31 PM > Subject: Re: question about when shuffle/sort start working > > 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" <jianmin_...@yahoo.com> 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 >> >> >> >> > > >
