[petsc-dev] Including petsc.h breaks user code

[Matthew Knepley]

On Mon, Sep 15, 2014 at 1:08 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:

>
>   Matt,
>
>    I ran with OpenMPI and got exactly the error you’d expect and what they
> reported "An error occurred in MPI_Type_size”. A simple use of the debugger
> would reveal where it happened. I suspect that MPICH is more generous when
> you call MPI_Type_size() with a null type, perhaps it just gives a size of
> zero.
>
>    I hunted around on the web and could not find a definitive statement of
> what MPI_Type_size() should do when passed an argument of a null datatype.
>

Evidently, standards will only get you so far.

   Matt


>    Barry
>
> On Sep 15, 2014, at 4:40 AM, Matthew Knepley <knepley at gmail.com> wrote:
>
> > On Sun, Sep 14, 2014 at 8:36 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:
> >
> >    Pierre,
> >
> >      Thanks for reporting this, it is, indeed our bug. In petsclog.h we
> have macros for the various MPI calls in order to log their usage, for
> example,
> >
> > #define
> MPI_Scatter(sendbuf,sendcount,sendtype,recvbuf,recvcount,recvtype,root,comm)
> \
> >  ((petsc_scatter_ct++,0) ||
> PetscMPITypeSize(&petsc_recv_len,recvcount,recvtype) ||
> MPI_Scatter(sendbuf,sendcount,sendtype,recvbuf,recvcount,recvtype,root,comm))
> >
> > but PetscMPITypeSize() simply called MPI_Type_size() which generated an
> MPI error for MPI_DATATYPE_NULL
> >
> > PETSC_STATIC_INLINE PetscErrorCode PetscMPITypeSize(PetscLogDouble
> *buff,PetscMPIInt count,MPI_Datatype type)
> > {
> >   PetscMPIInt mysize; return  (MPI_Type_size(type,&mysize) || ((*buff +=
> (PetscLogDouble) (count*mysize)),0));
> > }
> >
> > What error did you get? Why did I not get this error when I ran it? I
> ran with MPICH 3.0.4 since that was the one I had compiled for C++.
> >
> >   Matt
> >
> > In the branch barry/fix-usage-with-mpidatatypenull I have added a check
> for this special case and avoid the MPI_Type_size() call. I will put this
> branch into next and if all tests pass it will be merged into maint and
> master and be in the next patch release.
> >
> >    Thank you for reporting the problem.
> >
> >    Barry
> >
> > Barry still thinks MPI 1.1 is the height of HPC computing :-(
> >
> >
> >
> > On Sep 14, 2014, at 4:16 PM, Pierre Jolivet <jolivet at ann.jussieu.fr>
> wrote:
> >
> > > Hello,
> > > Could you please explain to me why the following example is not
> working properly when <petsc.h> (from master, with OpenMPI 1.8.1) is
> included ?
> > >
> > > $ mpicxx in-place.cpp  -I$PETSC_DIR/include
> -I$PETSC_DIR/$PETSC_ARCH/include -L$PETSC_DIR/$PETSC_ARCH/lib -lpetsc
> > > $ mpirun -np 2 ./a.out
> > > Done with the scatter !
> > > 0 0 0 0 (this line should be filled with 0)
> > > 1 1 1 1 (this line should be filled with 1)
> > > Done with the gather !
> > >
> > > $ mpicxx in-place.cpp  -I$PETSC_DIR/include
> -I$PETSC_DIR/$PETSC_ARCH/include -L$PETSC_DIR/$PETSC_ARCH/lib -lpetsc
> -DPETSC_BUG
> > > $ mpirun -np 2 ./a.out
> > > [:3367] *** An error occurred in MPI_Type_size
> > > [:3367] *** reported by process [4819779585,140733193388032]
> > > [:3367] *** on communicator MPI_COMM_WORLD
> > > [:3367] *** MPI_ERR_TYPE: invalid datatype
> > > [:3367] *** MPI_ERRORS_ARE_FATAL (processes in this communicator will
> now abort,
> > > [:3367] ***    and potentially your MPI job)
> > >
> > > Thank you for looking,
> > > Pierre
> > >
> > > <in-place.cpp>
> >
> >
> >
> >
> > --
> > What most experimenters take for granted before they begin their
> experiments is infinitely more interesting than any results to which their
> experiments lead.
> > -- Norbert Wiener
>
>


-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener
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