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

[Matthew Knepley]

On Mon, Feb 20, 2023 at 12:05 PM Matthew Knepley <knepley at gmail.com> wrote:

> 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.
>

Just to follow up, we have tests of the low-level communication (Plex tests
ex1, ex12, ex18, ex29, ex31), and then we have
tests that use halo exchange for PDE calculations, for example SNES
tutorial ex12, ex13, ex62. THe convergence rates
should be off if the halo exchange were wrong. Is there any example similar
to your code that is failing on your installation?
Or is there a way to run your code?

  Thanks,

     Matt


>   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/>
>


-- 
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/>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20230221/0af69dfb/attachment.html>