[MOAB-dev] possible bug in WriteHDF5Parallel.cpp

[Mark Filipiak]

Hi,

I think there is a bug in WriteHDF5Parallel.cpp (MOAB 4.6.3 and 4.6.2),
where an arbitrary MPI message tag is used:

ErrorCode WriteHDF5Parallel::communicate_shared_set_ids( const Range& owned,
                                                         const Range& remote
)
{
  ErrorCode rval;
  int mperr;
  const int TAG = 0xDEADF00;

...

      mperr = MPI_Irecv( &recv_buf[i][0], recv_buf[i].size(),
MPI_UNSIGNED_LONG,
                         procs[i], TAG, comm, &recv_req[i] );
CHECK_MPI(mperr);

...

    mperr = MPI_Isend( &send_buf[i][0], send_buf[i].size(),
MPI_UNSIGNED_LONG,
                       si->first, TAG, comm, &send_req[i] );

...

The value 0xDEADF00 gives me an MPI tag error when running the
parallel_hdf5_test after building MOAB on a Cray XC30 with the Gnu compiler.
The code should use an MPI enquiry function to get the maximum allowed value
for a tag (MPI_TAG_UB) and choose an arbitrary value less than this.  The
maximum allowed value is guaranteed to be >= 32767, so you could choose an
arbitrary value >= 0 and <= 32767.


Regards,

Mark

Mark Filipiak
EPCC
The University of Edinburgh
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