[petsc-users] DMPlex Halo Communication or Graph Partitioner Issue

[Matthew Knepley]

On Sat, Feb 18, 2023 at 12:00 PM Mike Michell <mi.mike1021 at gmail.com> wrote:

> As a follow-up, I tested:
>
> (1) Download tar for v3.18.4 from petsc gitlab (
> https://gitlab.com/petsc/petsc/-/tree/v3.18.4) has no issue on DMPlex
> halo exchange. This version works as I expect.
> (2) Clone main branch (git clone https://gitlab.com/petsc/petsc.git) has
> issues with DMPlex halo exchange. Something is suspicious about this main
> branch, related to DMPlex halo. The solution field I got is not correct.
> But it works okay with 1-proc.
>
> Does anyone have any comments on this issue? I am curious if other DMPlex
> users have no problem regarding halo exchange. FYI, I do not declare ghost
> layers for halo exchange.
>

There should not have been any changes there and there are definitely tests
for this.

It would be great if you could send something that failed. I could fix it
and add it as a test.

  Thanks,

     Matt


> Thanks,
> Mike
>
>
>> Dear PETSc team,
>>
>> I am using PETSc for Fortran with DMPlex. I have been using this version
>> of PETSc:
>> >>git rev-parse origin
>> >>995ec06f924a86c4d28df68d1fdd6572768b0de1
>> >>git rev-parse FETCH_HEAD
>> >>9a04a86bf40bf893fb82f466a1bc8943d9bc2a6b
>>
>> There has been no issue, before the one with VTK viewer, which Jed fixed
>> today (
>> https://gitlab.com/petsc/petsc/-/merge_requests/6081/diffs?commit_id=27ba695b8b62ee2bef0e5776c33883276a2a1735
>> ).
>>
>> Since that MR has been merged into the main repo, I pulled the latest
>> version of PETSc (basically I cloned it from scratch). But if I use the
>> same configure option with before, and run my code, then there is an issue
>> with halo exchange. The code runs without error message, but it gives wrong
>> solution field. I guess the issue I have is related to graph partitioner or
>> halo exchange part. This is because if I run the code with 1-proc, the
>> solution is correct. I only updated the version of PETSc and there was no
>> change in my own code. Could I get any comments on the issue? I was
>> wondering if there have been many changes in halo exchange or graph
>> partitioning & distributing part related to DMPlex.
>>
>> Thanks,
>> Mike
>>
>

-- 
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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