MATMPIAIJ preallocation may not be cleaned by MatDestroy?

[Barry Smith]

On Sep 24, 2009, at 12:10 PM, xiaoyin ji wrote:

> Hi all,
>
> I've finally fixed the problem with the increasing solving time for
> iterative call of ksp solver. The way is set mat type as MATAIJ
> instead of MATMPIAIJ. Here is the new codes of mat construction.
>
> MatCreate(PETSC_COMM_WORLD,&A);
> MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,ngridtot,ngridtot);
> MatSetType(A,MATAIJ);
> MatSetFromOptions(A);


> MPI_Comm_size(PETSC_COMM_WORLD,&size);
> if (size > 1){
> MatMPIAIJSetPreallocation(A,7,PETSC_NULL,2,PETSC_NULL);
> } else {
> MatSeqAIJSetPreallocation(A,7,PETSC_NULL);
> }

   You do not need to do the if test here. You only need to do
> MatMPIAIJSetPreallocation(A,7,PETSC_NULL,2,PETSC_NULL);
> MatMPIAIJSetPreallocation(A,7,PETSC_NULL,2,PETSC_NULL);

   PETSc automatically selects the appropriate one and ignores the  
inappropriate one.

    Barry

>
> The older version is like this, mat type is defined seperately based
> on the system size as MATMPIAIJ and MATSEQAIJ respectively. This code
> works ok in Fortran subroutines, but in C++ it will cause ksp solver
> getting slower and slower like a parabola, which may be a memory leak.
>
> MatCreate(world,&A);
>
> MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,ngridtot,ngridtot);
>
> // setup sparse matrix in either MATMPIAIJ or MATSEQAIJ format
> MPI_Comm_size(world,&size);
> if (size > 1) {
> MatSetType(A,MATMPIAIJ);
> MatSetFromOptions(A);
> MatMPIAIJSetPreallocation(A,7,PETSC_NULL,2,PETSC_NULL);
> } else {
> MatSetType(A,MATSEQAIJ);
> MatSetFromOptions(A);
> MatSeqAIJSetPreallocation(A,7,PETSC_NULL);
> }
>
> However, I think petsc library still have problem, as both codes
> should work in C++ or Fortran. Thanks.
>
> Best,
> Xiaoyin Ji