On 25/03/2011 14:10, bikash sharma wrote:
Hi, For my research project, I need to add a couple of functions in JobTracker.java source file to include additional information about TaskTrackers resource usage through heartbeat messages. I made those changes to JobTracker.java file. However, I am not very clear how to see these effects. I mean what are the next steps in terms of building the entire Hadoop code base, using the built distribution and installing it again in the cluster, etc?
If you are working with the Job Tracker you only need to rebuild the mapreduce JARs and push the new JAR out to the Job Tracker server, restart that process.
For more safety, put the same JAR on all the task trackers and shut down HDFS before the updates, but that's potentially overkil
Any elaborate updates on these will be very useful since I do not have much experience in doing modifications to Hadoop like huge code base and observing the effects of these changes.
I'd recommend getting everything working on a local machine single VM (the MiniMRCluster class helps), then move to multiple VMs and finally, if the code looks good, a real cluster with data you don't value.
-stee
