Process Groups: A mechanism for the coordination of and communication among processes in the Venus collective communication library

In programming massively parallel computers, it is often necessary to have sets of processes cooperate in performing certain computations and communications. Most run-time libraries require that such sets of processes be explicitly specified in the program. In the Venus run-time communication library however, a Process Group abstraction is used to enable implicit coordination of and communication over dynamically determined sets of processes. The Process Groups mechanism in Venus offers an object-oriented approach for handling sets of processes and enhances the debugging and monitoring of programs. The authors describe the Process Groups mechanism in Venus, illustrate its use on the class of N-body problems, and outline some of the data structures and algorithms used to implement this mechanism in Venus.