Python Parallel Programming Cookbook

Collective communication using Alltoall

The Alltoall collective communication combines the scatter and gather functionality. In mpi4py, there are three types of Alltoall collective communication:

• comm .Alltoall(sendbuf, recvbuf): The all-to-all scatter/gather sends data from all-to-all processes in a group
• comm.Alltoallv(sendbuf, recvbuf): The all-to-all scatter/gather vector sends data from all-to-all processes in a group, providing different amount of data and displacements
• comm.Alltoallw(sendbuf, recvbuf): Generalized all-to-all communication allows different counts, displacements, and datatypes for each partner

How to do it…

In the following example, we'll see a mpi4py implementation of comm.Alltoall. We consider a communicator group of processes, ...