[petsc-users] Petsc memory consumption keep increasing in my loop

[Medane TCHAKOROM]

Thanks Barry,

I can't share the orginal code i'am working on unfortunately.

But the example i wrote -- even if you do not that into account //SOME 
CODE HERE .. part -- give me , by using PetscMallocDump, some 
informations about memory that was not freed.

Based on the example code i sent, i was expecting that PetscMallocDump 
give no output.

Médane


On 24/09/2021 16:13, Barry Smith wrote:
>   The code you sent looks fine, it should not leak memory.
>
>   Perhaps the /// SOME CODE HERE.... is doing something that prevents the matrix from being actually freed. PETSc uses reference counting on its objects so if another object keeps a reference to the matrix then the memory of the matrix will not be freed until the reference count drops back to zero. For example if a KSP has a reference to the matrix and the KSP has not been completely freed the matrix memory will remain.
>
>    We would need to see the full code to understand why the matrix is not being freed.
>
>    Barry
>
>
>> On Sep 24, 2021, at 10:08 AM, Medane TCHAKOROM <medane.tchakorom at univ-fcomte.fr> wrote:
>>
>> Hello,
>>
>> I have problem with a code i'am working on.
>>
>> To illustrate my problem, here is an example:
>>
>>
>> int main(int argc, char *argv[])
>> {
>>
>>      PetscErrorCode ierr;
>>
>>      ierr = PetscInitialize(&argc, &argv, (char *)0, NULL);
>>      if (ierr)
>>          return ierr;
>>
>>      int i = 0;
>>      for (i = 0; i < 1; i++)
>>      {
>>          Mat A;
>>          ierr = MatCreate(PETSC_COMM_WORLD, &A);
>>          CHKERRQ(ierr);
>>          ierr = MatSetSizes(A, 16, 16, PETSC_DECIDE,PETSC_DECIDE);
>>          CHKERRQ(ierr);
>>          ierr = MatSetFromOptions(A);
>>          CHKERRQ(ierr);
>>          ierr = MatSetUp(A);
>>          CHKERRQ(ierr);
>>
>>
>>          ierr = MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY);
>>          CHKERRQ(ierr);
>>          ierr = MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY);
>>          CHKERRQ(ierr);
>>
>>
>>
>>          /// SOME CODE HERE....
>>
>>          MatDestroy(&A);
>>
>>
>>      }
>>
>>
>>      FILE *fPtr;
>>      fPtr = fopen("petsc_dump_file.txt", "a");
>>      PetscMallocDump(fPtr);
>>      fclose(fPtr);
>>
>>      ierr = PetscFinalize();
>>      CHKERRQ(ierr);
>>
>>      return 0;
>> }
>>
>>
>>
>> The problem is , in the loop, the memory consumption keep increasing till the end of the program.
>>
>> I checked memory leak with PetscMallocDump, and found out that the problem may be due to matrix creation.
>>
>> I'am new to Petsc and i don't know if i'am doing something wrong. Thanks
>>
>>
>> Médane
>>