Charm++: Parallel Objects

CS 641 Lecture, Dr. Lawlor

Charm++ is a little parallel library for C++, where a small translator generates "proxy" objects that let you call methods on objects living on distant CPUs. These "parallel objects" make it a lot easier to get:

Better initial load balance, by splitting the problem down into many objects (more than the number of processors).
Run-time responsive load balancing, by "migrating" objects from overloaded to underloaded processors. Charm++ can do this at runtime without screwing up the running application, because applications talk to objects, not processors.
Computation/communication overlap. The fact that objects only run when their network messages arrive has the surprising benefit that less CPU time is wasted "blocked waiting for data" as is common in MPI. Many independent pieces of the computation can intelligently share the CPU.

There's a pretty good tutorial here.