[mpich-discuss] too many communicators

Jack Lee jack.lee at kcl.ac.uk
Wed Dec 12 14:23:31 CST 2012

Hi there,

I'm using an external matrix solver library which is resulting in error, 
either in mpi_comm_dup or mpi_comm_split. This happens after rebuilding 
the matrix and calling the solver many times (hundreds of times or 
more), during which the solver object is destroyed and recreated. These 
routines are never called from my code. And as far as I can see in the 
solver source, there are corresponding calls to mpi_comm_free, but it's 
entirely possible that my assessment is incorrect. The MPI error 
messages and strack trace printed upon crash are quite brief, and I'm 
finding it difficult to tackle this issue.

What I'd like to determine first is whether fault is on my side (e.g. 
perhaps I'm not calling the clean-up routines properly). Is there a way 
to find out how many context id's are in use at a given point?

-- Ubuntu 12.04, mpich2 1.4, gcc/gfortran. The linear solver is 
SuperLU_dist 2.5.

Many thanks,

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