Hey all, I was wondering if there was any example code I could look at that uses a combiner. Creating your own Combiner is easy enough, e.g. DoubleSumCombiner, but I am confused as to how/where I would use the classes in my code.
For example, say I wanted to utilize the DoubleSumCombiner class to sum up all of the messages arriving at a particular vertex at the beginning of the superstep, and I wanted to do this for each vertex in the graph. Where should I instantiate a DoubleSumCombiner, when should I call the combine() and createInitialMessage() methods, etc. in the compute() method? What further confuses me is that I see that the MasterCompute class has methods for setCombiner() and getCombiner(), and that there is also a command line option -c to specify a Combiner. I'm not really sure if these are even necessary, but if they are, I don't know how these come into play either. Some clarification or direction towards an example would be nice! Thanks, -- Kyle Orlando Computer Engineering Major University of Maryland
