Verification of Halting Properties for MPI Programs Using Nonblocking Operations

We show that many important properties of certain MPI programs can be verified by considering only a class of executions in which all communication takes place synchronously. In previous work, we showed that similar results hold for MPI programs that use only blocking communication (and avoid certain other constructs, such as MPI_ANY_SOURCE); in this paper we show that the same conclusions hold for programs that also use the nonblocking functions MPI_ISEND, MPI_IRECV, and MPI_WAIT. These facts can be used to dramatically reduce the number of states explored when using model checking techniques to verify properties such as freedom from deadlock in such programs.