[petsc-dev] HDF5 usage in PETSc without MPI? WTF? Totally broken?

[Barry Smith]

  I am confused about the usage of HDF5 from PETSc.

   In hdf5.py

  def configureLibrary(self):
    if self.libraries.check(self.dlib, 'H5Pset_fapl_mpio'):
      self.addDefine('HAVE_H5PSET_FAPL_MPIO', 1)
    return

  So PETSc does not require HDF5 to have been built using MPI (for example if it was built by someone else without MPI.)

  In PetscErrorCode  PetscViewerFileSetName_HDF5(PetscViewer viewer, const char name[])

#if defined(PETSC_HAVE_H5PSET_FAPL_MPIO)
  PetscStackCallHDF5(H5Pset_fapl_mpio,(plist_id, PetscObjectComm((PetscObject)viewer), info));
#endif

  so it only sets collective IO if the symbol was found and hence HDF5 was built for MPI

  But in places like  VecView_MPI_HDF5(Vec xin, PetscViewer viewer)

   it uses MPI as if it was collective? Though it might not be because hdf5 could have been built without MPI

  So if I build PETSc with a non-MPI hdf5 and yet use the hdf5 viewer in parallel; do the generated hdf5 files contain garbage?

  It seems to me we need to have hdf5.py REQUIRE the existence of H5Pset_fapl_mpio?

  Barry