Thanks a lot steve. I will go through the link. Ravi. On Mon, Jan 4, 2010 at 8:14 PM, Steve Loughran <[email protected]> wrote:
> Ravi wrote: > >> Hi, >> I have designed a mapreduce algorithm for all pairs shortest paths >> problem. As a part of the implementation of this algorithm, I have written >> the following mapreduce job. It is running well and producing desired output >> in pseudo distributed mode. I have used a machine with ubuntu 8.04 and >> hadoop-0.18.3 to run the job in pseudo distributed mode. When I tried to run >> the same program on a cluster of 4 machines(each running Redhat linux 9) >> with the same version of hadoop(hadooop-0.18.3), the program is not giving >> any errors but its not giving any output as well(The output file is blank). >> This is the first time I am facing this kind of problem. >> I am attaching the jar file of the program and sample inputs: out1 and >> out2 as well.(The program need to read input from these two files) >> I have searched the archive but didn't find any mail mentioning this >> problem. I have googled, but it was of no use. >> I am not able to find out what am I missing in the code. >> > > First, the bad news: nobody is going to debug your program for you. It's > your program, you get to learn about distributed debugging. We all have our > own programs and their bugs to deal with, and if its a problem with your > physical cluster, then nobody but you are in a psition to fix. > > Now, the good news: the skills you learn on this simple app scale well to > bigger clusters and more complex programs. Accordingly, it is absolutely > essential that you do learn this process now, while your problem is still > small. > > http://wiki.apache.org/hadoop/HowToDebugMapReducePrograms > > * Tell Hadoop to save all failed outputs with keep.failed.task.files > * See what gets retained on the worker machines, and their logs > * log at log4j's debug level in your code, run the nodes with your classes > set to log at debug level (leave the rest at info, for now). Leave the > logging settings in, they may come in useful later, just check with > log.isDebugEnabled() before constructing strings or other work to create the > log entries. > > > > Should I be using hadoop-0.20? > > > > It's not likely to magically make your problem go away, if that is what you > were wondering. >
