I have a few questions i am trying to understand:
1. Is each input split same as a record, (a rec can be a single line or multiple lines).
2. Is each Task a collection of few computations or attempts.
For ex: if i have a small file with 5 lines.
By default there will be 1 line on which each map computation is performed.
So totally 5 computations r done on 1 node.
This means JT will spawn 1 JVM for 1 Tasktracker on a node
and another JVM for map task which will instantiate 5 map objects 1 for each line.
The MT JVM is called the task which will have 5 attempts for each line.
This means attempt is same as computation.
Please let me know if anything is incorrect.
Sonal Goyal 2013-09-27, 08:31