P
Nov 27, 2012

Not getting performance with MapReduce

I am working on hadoop mapreduce to get performance benefit but when I run my program on hadoop it takes about 37 minutes where as it takes only about 5 minutes for simple C++ program for doing the same task..

11/27/2012
Here's some additional info.

Map/Reduce Tutorial
http://hadoop.apache.org/docs/r0.20.2/mapred_tutorial.html

"This document comprehensively describes all user-facing facets of the Hadoop Map/Reduce framework and serves as a tutorial."
t
11/27/2012

I'm not sure what the issue is or how familiar you are with MapReduce.  Yahoo has a pretty good Hadoop tutorial that has two modules on MapReduce.  Perhaps that may be of some help.  Good luck! 

http://developer.yahoo.com/hadoop/tutorial/module4.html

http://developer.yahoo.com/hadoop/tutorial/module5.html

P
11/28/2012

I am new to Mapreduce and I am using Hadoop Pipes for that. I have an input file which contains the number of records, one per line. I have written one simple program to print those lines in which three words are common. In map function i have emiited the word as a key and record as a value and compared those records in reduce function. I compared Hadoop's performance with simple C++ program in which I read the records from file and split it into words and load the data, word as a key and record as a value in map and after loading all the data I compared that data. But I found that for doing the same task Hadoop MapReduce takes long time compared with plain C++ program.

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