Broadcast

This type falls in the collective mode of communication where a data source is transferred to all processes (ranks) in a communicator. Just like the following image.

_images/broadcast.png

In the following example, a string variable data is broadcasted from rank 0 to all the other ranks within the communicator.

from mpi4py import MPI

comm = MPI.COMM_WORLD
rank = comm.Get_rank()

if rank == 0:
    data = ['r','e','d']

else:
    data = None

data = comm.bcast(data, root=0)
print('Rank: ',rank,', data: ' ,data)
_images/broadcast2.png

Broadcasting involves sending data to all processes (ranks) in a communicator. For instance, in the image above has the data variable in rank 1, and after broadcast , it is sent to all the other ranks within the communicator.

comm.bcast(obj, root=0)
Broadcasts obj from root.
Parameters:

  • obj – Any

  • root – int

Return type:

Any