dolfin team mailing list archive

[Garth Wells <705401@xxxxxxxxxxxxxxxxxx>]

On 22/01/11 19:44, Joachim Haga wrote:
> To reiterate, the problem with MPI_Finalize is not the only one. There
> are also failures before the program ends, including the inability to
> create an ML preconditioner object.
> 

Could you register a new bug report for this? It would be easier if we
can separate out the import order and MPI finalise issue from other
problems.

Garth

> I think it's quite ok to say to the user, "import PyTrilinos before
> dolfin", even though there are real bugs that should eventually be
> addressed. I understand my previous proposal (try: import PyTrilinos;
> except: pass) is unacceptable. How do you feel about dolfin blocking
> import of PyTrilinos through import hooks, something like the following?
> 
> def _block_import(name, reason):
>     import sys
>     prefix = name+'.'
>     class Importer(object):
>         def find_module(self, fullname, path=None):
>             if fullname == name or fullname.startswith(prefix):
>                 if not name in sys.modules:
>                     error('%s must be imported before dolfin (see %s)'%(name, reason))
>                 return None
>     sys.meta_path.append(Importer())
> _block_import('PyTrilinos', 'https://bugs.launchpad.net/dolfin/+bug/705401')
>

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https://bugs.launchpad.net/bugs/705401

Title:
  When PyTrilinos is imported after dolfin, bad things happen

Status in DOLFIN:
  New

Bug description:
  When using PyTrilinos (ML in particular), the order of imports is
  important. If dolfin is imported first, it crashes at exit, and there
  are problems also with constructing preconditioners etc.

  It looks like it has to do with MPI initialisation, but I haven't
  looked at it closely.

  A simple workaround may be to try an import ML in dolfin/__init__.py
  (just import, not expose) so that it gets initialised. I don't know if
  the performance hit is worth it. It would of course be better to find
  a proper fix.

  Otherwise, it's nice to have it documented here. For google::
  >>> import dolfin
  >>> from PyTrilinos import ML
  >>> exit()
  *** An error occurred in MPI_Finalize
  *** after MPI was finalized
  *** MPI_ERRORS_ARE_FATAL (your MPI job will now abort)
  [rodin:17864] Abort after MPI_FINALIZE completed successfully; not able to guarantee that all other processes were killed!