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From aa...@buffalo.edu
Subject Help in Hadoop
Date Sun, 22 Nov 2009 22:25:55 GMT
Hello Everybody,
                I have a doubt in a map reduce program and I would appreciate any
help. I run the program using the command bin/hadoop jar HomeWork.jar prg1 input
output. Ideally from within prg1, I want to sequentially launch 10 map- reduce
tasks. I want to store the output of all these map reduce tasks in some file.
Currently I have kept the input format and output format of the jobs as
TextInputFormat and TextOutputFormat respectively. Now I have the following
questions.

1. When I run more than 1 task from the same program, the output file of all the
tasks is same. The framework does not allows the 2   map reduce task to have the
same output file as task 1.

2. Before the 2 task launches I also get this error 

Cannot initialize JVM Metrics with processName=JobTracker, sessionId= - already
initialized

3. When the 2 map reduce tasks writes its output to file "output", wont the
previous content of this file get over written ?

Thank You

Abhishek Agrawal

SUNY- Buffalo
(716-435-7122)




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