[OMPI users] overlapping communicators?

[tsilva]

Hi,

I have a Multiple Program Multiple Data with three programs running in  
parallel, say A, B and C. C is much slower so in order to balance the  
load I want to parallelize C into C0 to Cn (SPMD). There are very  
frequent communications between Ci processes and not so frequent, but  
still multiple times per second, between A, B and C0. I have running  
versions of ABC MPMD and the C*N SMPD.

I was thinking of creating two communicators with C0 being a member of  
both, but I am told this is bad practice although I don't really know  
what the pitfalls are. An alternative would be to create and close the  
ABC communicator every time it is used, but I am worried about the  
cost of this operations and about making the code look messy. I would  
appreciate any advice onn this issue.

Thanks,
Tiago