Fix 1: Use Irecv

Do i=1,n_neighbors Call MPI_Irecv(edge,len,MPI_REAL,nbr(i),tag, comm,request(i),ierr)Enddo Do i=1,n_neighbors Call MPI_Send(edge, len, MPI_REAL, nbr(i), tag, comm, ierr)EnddoCall MPI_Waitall(n_neighbors, request, statuses, ierr)

Do i=1,n_neighbors Call MPI_Irecv(edge,len,MPI_REAL,nbr(i),tag, comm,request(i),ierr) Enddo Do i=1,n_neighbors Call MPI_Send(edge, len, MPI_REAL, nbr(i), tag, comm, ierr) Enddo Call MPI_Waitall(n_neighbors, request, statuses, ierr)