You can write output in the mapper's close() method, which will be called after the last line of input is processed. When I was last doing this (~ version 17), it was a bit of a pain, since by default you didn't have access to the relevant output object, making it necessary to store it in a field in the object. I don't know if the interfaces have been improved since then.
-Chris 2009/12/17 Gang Luo <[email protected]>: > Hi all, > most of the time, we focus on the map function to decide whether to output a > record and what to output. Now I want to do something at the map task level. > I want to output a record when a map task finish and this record should be > processed by reducer properly. Is there any way to output (like > output.collect in map function) a record outside map function? > > If that is impossible, to know whether I meet the last line for this map task > is also helpful. Does anyone know how to tell whether the line I am > processing now in map function is the last line for this map task? > > Thanks. > > -Gang > > > ___________________________________________________________ > 好玩贺卡等你发，邮箱贺卡全新上线！ > http://card.mail.cn.yahoo.com/ >
