Hi All,
I'm a Mapreduce newbie, what I want to know is that, say I have a mapper class:
public Class Map implements Mapper {
public List A;
public static List B;
public Map(){ //class constructor
System.out.println("Im initializing");
}
@Override
protected void map(………){
System.out.println("Im inside a mapper");
…….
}
}
when I run this mapper on a multi-machine hadoop configuration, will hadoop
instantiate
multiple instances of this class then transmit them to every remote machine?
So in a remote
machine will the map(…) method be able to access List A and List B locally from
its own memory?
If yes, in the map method, what if I run System.out.println, will printed
message be only shown on
the remote machine but not the machine I start the whole map reduce job?
Thanks.
Eason
