Initialization and Finalization

The user is responsible for initializing and finalizing Petsc. The functions here facilitate doing so.

The command using PETSc2 will initialize MPI if it is not already initialized and finalize it when Julia exits. The user is responsible for initializing and finalizing PETSc itself. Using the Base.atexit() function is useful for managing the finalization of libraries.

Also note that the user is entirely responsible for finalizing PETSc objects via PetscDestroy when they are no longer needed. Unforturnately, finalizers cannot be used because they do not guarantee order of destruction, and they are run after Base.atexit() hooks, so it is possible MPI could be finalized before the PETSc objects have been freed.