Thank you Robert, infact i didn't specify any job.jar so i think that hadoop have some mechanism to guess the jar
2011/5/27 Robert Evans <[email protected]> > Francesco, > > The mapreduce client will create a jar called job.jar and place it in HDFS > in a staging directory. This is the jar that you specified to your job > conf, or I believe that it tries to guess the jar based off of the Mapper > class and the Reducer class but I am not sure of that. Once the job tracker > has told a TaskTracker to run a given job the TaskTracker will download the > jar, and then fork off a new JVM to execute the Mapper or Reducer. If you > jar has dependencies then these usually have to be shipped with it as part > of the cache archive interface. > > --Bobby Evans > > > On 5/27/11 9:16 AM, "Francesco De Luca" <[email protected]> wrote: > > Anyone knows the mechanism that hadoop use to load Map and Reduce class on > the remote node > where the JobTracker submit the tasks? > > In particular, how can hadoop retrieves the .class files ? > > Thanks > >
