Can I write from different MPI_Irecv into the same buffer/array at different index positions?

Question

MPI_IRecv(&myArr[0], 5, MPI_INT, 1, MPI_ANY_TAG, MPI_COMM_WORLD, request);
MPI_IRecv(&myArr[5], 5, MPI_INT, 2, MPI_ANY_TAG, MPI_COMM_WORLD, request);
MPI_IRecv(&myArr[10], 5, MPI_INT, 3, MPI_ANY_TAG, MPI_COMM_WORLD, request);

Hi, does c/mpi allow you to write into different areas of the same array from an mpi non-blocking receive? The above code shows roughly what I would like to achieve.

Answer 1

Yes. You aren't allowed to read or modify the buffer of a non-blocking communications request until the communications are done; but as far as MPI are concerned, non-overlapping regions of the same array are completely different buffers.