Junchao,
Thanks for checking this.
Could you use PetscRegisterFinalize()?
Barry
> On Aug 14, 2021, at 10:46 PM, Junchao Zhang <[email protected]> wrote:
>
>
>
> On Thu, Aug 12, 2021 at 11:22 AM Barry Smith <[email protected]
> <mailto:[email protected]>> wrote:
>
> User visible communicators generally do not have a keyval attached. Rather
> the keyval is attached to the inner communicator; because we don't want both
> PETSc and the user doing MPI operations on the same communicator (to prevent
> mixing up tags).
>
> I think PetscShmCommGet() is wrong. I think it should not call
> MPI_Comm_get_attr(globcomm,Petsc_Counter_keyval,&counter,&flg); but should
> call PetscCommDuplicate() and use that communicator to stash the pshmcomm;
> then you would not have the problem you are having.
> Barry, I think it over and find the problem is: if I PetscCommDuplicate()
> the outer comm in PetscShmCommGet(), then I can not find a place to destroy
> the inner communicator (note usually petsc inner communciators are destroyed
> with petsc objects. Doing what you said breaks the rule)
>
> PetscShmCommGet() was designed to help doing OpenMP multithreading on a
> communicator that some petsc objects live in. So requiring the input
> communicator to be petsc comm is not totally nonsense.
>
> I tried another approach: Don't check whether the input comm in
> PetscShmCommGet(globcomm,&pshmcomm) is an outer comm or an inner comm. We
> instead check its Petsc_ShmComm_keyval. If it does not have one, we just
> create one for it (along with a new shared memory communicator)
> With that, one is able to call PetscShmCommGet(PETSC_COMM_WORLD, ...). The
> problem is we attached an attribute to PETSC_COMM_WORLD. It is deleted inside
> MPI_Finalize(). PETSc -malloc_dump complains of unfreed memory (since I
> used PetscMalloc inside PetscShmCommGet). I could
> bypass PetscMalloc and directly use malloc() to avoid this situation. Is it
> worthy?
>
>
>
> Barry
>
>
>
> > On Aug 12, 2021, at 11:05 AM, Pierre Jolivet <[email protected]
> > <mailto:[email protected]>> wrote:
> >
> > Hello,
> > Is there a specific reason why PETSC_COMM_WORLD is not a PETSc
> > communicator, i.e., has no Petsc_Counter_keyval attached?
> > ierr = PetscOmpCtrlCreate(PETSC_COMM_WORLD,nthreads,&ctrl);CHKERRQ(ierr);
> > yields
> > [0]PETSC ERROR: Bad MPI communicator supplied must be a PETSc communicator
> > [0]PETSC ERROR: #1 PetscShmCommGet() at src/sys/utils/mpishm.c:60
> > [0]PETSC ERROR: #2 PetscOmpCtrlCreate() at src/sys/utils/mpishm.c:340
> >
> > Thanks,
> > Pierre
>
