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

[Matthew Knepley]

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
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