it seems that the paradigm offered by Giraph/Pregel is very similar to the programming paradim of PVM , and to a lesser degree, MPI. using PVM, we often engages in such "iterative cycles" where all the nodes sync on a barrier and then enters the next cycle.
so what is the extra features offered by Giraph/Pregel? I can see persistence/restarting of tasks, and maybe abstraction of the user-code-specific part into the API so that users are not concerned with the actual message passing (message passing is done by the framework). Thanks Yang
