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Subject: Re: [OMPI devel] Fortran 90 Interface
From: N.M. Maclaren (nmm1_at_[hidden])
Date: 2009-01-23 07:45:40

On Jan 23 2009, Jeff Squyres wrote:
>On Jan 23, 2009, at 12:30 AM, David Robertson wrote:
>> I have looked for both MPI_COMM_WORLD and mpi_comm_world but neither
>> can be found by totalview (the parallel debugger we use) when I
>> compile with "USE mpi". When I use "include 'mpif.h'" both
>> MPI_COMM_WORLD and mpi_comm_world are zero.
>I'm afraid I don't know why that would be. :-(

It is fairly common for debuggers to not handle Fortran modules properly;
that is very often not the fault of the debugger, but because the compiler
has changed from one undocumented format to another.

However, if I had to bet on the cause of this, I would bet an installation
problem, with at least one set of paths or parameters set incorrectly or
incompatibly with other ones. Now, WHICH set? Dunno.

>> MPI_COMM_WORLD is set to a large integer (1140850688) in MPICH2 so I
>> wonder if there is something in HDF5 and/or NetCDF4 that doesn't
>> like 0 for the communicator handle. At any rate, you have given me
>> some ideas of things to check in the debugger tomorrow. Is there a
>> safe way to change what MPI_COMM_WORLD is set to in OpenMPI?
>No. Open MPI's Fortran MPI_COMM_WORLD is pretty much hard-wired to 0.

That's a mistake. But probably non-trivial to fix.

Nick Maclaren,
University of Cambridge Computing Service,
New Museums Site, Pembroke Street, Cambridge CB2 3QH, England.
Email: nmm1_at_[hidden]
Tel.: +44 1223 334761 Fax: +44 1223 334679