thanks :)
On Mon, Mar 3, 2008 at 5:23 AM, Owen O'Malley <[EMAIL PROTECTED]> wrote: > > > On Mar 2, 2008, at 12:53 PM, momina khan wrote: > > > i have trouble comprehending what shuffle phase is exactly ... can > > anyone plz exlpain in for me.... and also point out the name of the > > class that the thread for shuffle runs and also the class spawning the > > thread itself! > > The shuffle phase is the data motion from the map output to the > reduce input. In general, it involves each reduce collecting outputs > from each map, which is why it is called the "shuffle". The > TaskTracker where the map ran has a jetty server that gives out the > map outputs. The ReduceTask copies the map outputs as they finish. > You can look at ReduceTask.java for the client side of the shuffle. > > -- Owen >
