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From Alberto Andreotti <albertoandreo...@gmail.com>
Subject Poor scalability with map reduce application
Date Tue, 21 Jun 2011 15:03:32 GMT

I'm working with an application to calculate the temperatures of a squared
board. I divide the board in a mesh, and represent the board as a list of
(key, value) pairs with a key being the linear position of a cell within the
mesh, and the value its temperature.
I distribute the data during the map and calculate the temperature for next
step in the reduce. You can see a more detailed explanation here,


but the basic idea is the one I have just mentioned.
The funny thing is that the more nodes I add the slower it runs!. With 7
nodes it takes 16 minutes, but with 4 nodes it takes only 8 minutes.
You can see the code in file HeatTransfer.java which is found here,


thanks in advance!

José Pablo Alberto Andreotti.
Tel: 54 351 4730292
Móvil: 54351156526363.
MSN: albertoandreotti@gmail.com
Skype: andreottialberto

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