[petsc-users] DMPlexCreateSection crashed with larger number of processors

[Mike Michell]

It looks like NULL PETScIS is obtained from DMGetStratumIS() which is shown
in the previously attached code. Currently, "marker" label is used to
define default bcPointIS pointer with numBC=1 through DMGetStratumIS(), and
it seems that if a certain proc does not have any boundary from this
"marker" label, the DMPlexCreateSection() crashes.

The PETSc's manual page for DMPlexCreateSection() says "bcPoints" is an IS
holding points to which each boundary condition applies. So, by including
no boundary for a certain distributed mesh block, it looks very natural
that this function crashes. How can I not to pass a NULL PETScIS in this
case? Is there any specific way for that (or a trick)?

Thanks,
Mike


> On Wed, Jul 6, 2022 at 3:42 PM Mike Michell <mi.mike1021 at gmail.com> wrote:
>
>> I am passing NULL for IS Permutation as;
>>
>> call
>> DMPlexCreateSection(dm_geom,nolabel,pNumComp,pNumDof,numBC,pBcField,pBcCompIS,pBcPointIS,PETSC_NULL_IS,section,ierr)
>>
>> Should I define non-NULL IS Permutation before I call
>> DMPlexCreateSection() to avoid the issue?
>>
>
> No, the problem is not the perm argument. To be sure, we should get a
> stack trace with line numbers (use a debug build). To me it looked
> like you passed a NULL IS to DMAddBoundary().
>
>   Thanks,
>
>     Matt
>
>
>> Thanks,
>> Mike
>>
>>
>> On Wed, Jul 6, 2022 at 12:57 PM Mike Michell <mi.mike1021 at gmail.com>
>>> wrote:
>>>
>>>> Hi, I am using DMPlex for a FVM code written in Fortran that uses
>>>> DMPlexCreateSection() to prepare an output file in vtu format. A domain of
>>>> interest has around 5000 node points and with small number of processors
>>>> (such as nproc=3), the DMPlexCreateSection() works fine. However, if a
>>>> larger number of procs (such as nproc=20) is used,  DMPlexCreateSection()
>>>> crashes with error message below. It looks very similar problem in a
>>>> previous PETSc user inquiry: " [petsc-dev] DMPlexCreateSection crash
>>>> in a no-boundary corner case
>>>> <https://lists.mcs.anl.gov/pipermail/petsc-dev/2013-November/014049.html>
>>>> "
>>>>
>>>
>>> Yes, the recommendation is not to pass a NULL PetscIS to the
>>> AddBoundary() routine. Are you doing this?
>>>
>>>   Thanks,
>>>
>>>      Matt
>>>
>>>
>>>
>>>> When I call DMPlexCreateSection(), a nullified pointer
>>>> "nolabel(:)=>NULL()" is provided. What is a possible solution to this
>>>> problem? It looks like there is a problem with a processor that does not
>>>> have any boundaries. A piece of the source code is attached to show how
>>>> the  DMPlexCreateSection() is used in the code.
>>>>
>>>> Thanks,
>>>> Mike
>>>>
>>>> [16]PETSC ERROR: --------------------- Error Message
>>>> --------------------------------------------------------------
>>>> [16]PETSC ERROR: Null argument, when expecting valid pointer
>>>> [16]PETSC ERROR: Null Pointer: Parameter # 1
>>>> [16]PETSC ERROR: See https://petsc.org/release/faq/ for trouble
>>>> shooting.
>>>> [16]PETSC ERROR: Petsc Release Version 3.17.0, unknown
>>>> [16]PETSC ERROR: #1 ISGetLocalSize() at
>>>> [16]PETSC ERROR: #2 DMPlexCreateSectionBCDof() at
>>>> [16]PETSC ERROR: #3 DMPlexCreateSection() at
>>>>
>>>
>>>
>>> --
>>> 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
>>>
>>> https://www.cse.buffalo.edu/~knepley/
>>> <http://www.cse.buffalo.edu/~knepley/>
>>>
>>
>
> --
> 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
>
> https://www.cse.buffalo.edu/~knepley/
> <http://www.cse.buffalo.edu/~knepley/>
>
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