[petsc-users] petsc init in class constructor

[Stefano Zampini]

Sorry,
I realized I replied to Feng and not to the list. Below is my previous email.

Feng,

Your class is fine as long as the constructor of your solver is called AFTER MPI_Init, and the destructor BEFORE MPI_Finalize.
This means that you cannot have something like

int main (int argc, char**argv)
{
 MPI_Init();
 solverpetsc S(argc,argv);
 MPI_Finalize();
 return 0;
} 

as the destructor for S will be called after MPI_Finalize().

If you call PetscInitialize before MPI_Init, PETSc will call it for you. But then, it will also call MPI_Finalize during PetscFinalize().

so, the following code will abort at any_MPI_call()

int main (int argc, char**argv)
{
 solverpetsc *S;

 S = new solverpetsc(argc,argv);
 ….
 <here you can use MPI>
 ….
 delete S;
 any_MPI_call();
 return 0;
}
On Oct 6, 2016, at 11:42 AM, Stefano Zampini <stefano.zampini at gmail.com> wrote:

>> 
>> Long story short: I'd encourage you not to initialize PETSc in a constructor, unless you know exactly what you are doing and can control the possible side effects.
>> 
> 
> completely agree on that.
>