with such a small data set who knows what will happen: you are probably hitting minimal limits of some kind
repeat this with more data Miles 2009/5/7 Foss User <foss...@gmail.com>: > I have two reducers running on two different machines. I ran the > example word count program with some of my own System.out.println() > statements to see what is going on. > > There were 2 slaves each running datanode as well as tasktracker. > There was one namenode and one jobtracker. I know there is a very > elaborate setup for such a small cluster but I did it only to learn. > > I gave two input files, a.txt and b.txt with a few lines of english > text. Now, here are my questions. > > (1) I found that three mapper tasks ran, all in the first slave. The > first task processed the first file. The second task processed the > second file. The third task didn't process anything. Why is it that > the third task did not process anything? Why was this task created in > the first place? > > (2) I found only one reducer task, on the second slave. It processed > all the values for keys. keys were words in this case of Text type. I > tried printing out the key.hashCode() for each key and some of them > were even and some of them were odd. I was expecting the keys with > even hashcodes to go to one slave and the others to go to another > slave. Why didn't this happen? > -- The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336.
