A fun scenario was proposed in the MPI Forum today.  What do you think this code will do?

MPI_Comm comm, save;
MPI_Request req;
MPI_Init(NULL, NULL);
MPI_Comm_dup(MPI_COMM_WORLD, &comm);
MPI_Comm_rank(comm, &rank);
save = comm;
MPI_Isend(smsg, 4194304, MPI_CHAR, rank, 123, comm, &req);
MPI_Comm_free(&comm);
MPI_Recv(rmsg, 4194304, MPI_CHAR, rank, 123, save, ... Read More