[dune-pdelab] Fwd: Fwd: solver fails to reset correctly after FMatrixError (singular matrix)

[Markus Blatt]

On Wed, Jul 10, 2019 at 02:39:09PM +0200, Nils-Arne Dreier wrote:
> I just talked to Jö. We guess that the problem is, that the exception is
> only thrown on one rank, say rank X. All other ranks do not know that
> rank X failed and proceed as usual, at some point all these ranks
> waiting for communication of rank X. That is the deadlock that you see.
> 
> You may want to have a look at Dune::MPIGuard in
> dune/common/parallel/mpiguard.hh. It makes it possible to propagate the
> error state to all ranks.
> 

One could also argue that if this happens in OneStepMethod of PDELab then
PDELab (in the long run) should make sure that the behaviour is consistent
across all processors...

Just my 2 cents.

Markus

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