hadoop-mapreduce-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Sai Sai <saigr...@yahoo.in>
Subject Re: Input Split vs Task vs attempt vs computation
Date Fri, 27 Sep 2013 05:12:53 GMT
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.

View raw message