[petsc-users] parallel computing error

[Matthew Knepley]

On Wed, May 3, 2023 at 6:05 AM ­권승리 / 학생 / 항공우주공학과 <ksl7912 at snu.ac.kr>
wrote:

> Dear developers
>
> I'm trying to use parallel computing and I ran the command 'mpirun -np 4
> ./app'
>
> In this case, there are two problems.
>
> *First,* I encountered error message
> ///
> [0]PETSC ERROR: [1]PETSC ERROR: --------------------- Error Message
> --------------------------------------------------------------
> [1]PETSC ERROR: Invalid argument
> [1]PETSC ERROR: Comm must be of size 1
> ///
> The code on the error position is
> MatCreateSeqDense(PETSC_COMM_SELF, nns, ns, NULL, &Kns));
>

1) "Seq" means sequential, that is "not parallel".

2) This line should still be fine since PETSC_COMM_SELF is a serial
communicator

3) You should be checking the error code for each call, maybe using the
CHKERRQ() macro

4) Please always send the entire error message, not a snippet

  THanks

     Matt


> Could "MatCreateSeqDense" not be used in parallel computing?
>
> *Second*, the same error message is repeated as many times as the number
> of cores.
> if I use command -np 4, then the error message is repeated 4 times.
> Could you recommend some advice related to this?
>
> Best,
> Seung Lee Kwon
>
> --
> Seung Lee Kwon, Ph.D.Candidate
> Aerospace Structures and Materials Laboratory
> Department of Mechanical and Aerospace Engineering
> Seoul National University
> Building 300 Rm 503, Gwanak-ro 1, Gwanak-gu, Seoul, South Korea, 08826
> E-mail : ksl7912 at snu.ac.kr
> Office : +82-2-880-7389
> C. P : +82-10-4695-1062
>


-- 
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/20230503/49c51118/attachment.html>