[petsc-dev] Avoid use of static in PETSc functions

[Jed Brown]

The particular instance of caching for performance might be able to be
removed after

https://bitbucket.org/petsc/petsc-dev/changeset/4c3566b6cf576d089811005e78b5a1ad26db2853

since it removed several lookups and indirections.

The caching was always an ugly beast due to the ABA problem.


On Thu, Nov 15, 2012 at 7:56 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:

>
>    PetscInitialize() and PetscFinalize() are reentrant. These means that
> one can call them several times in the same program (one must call
> MPI_Int() and MPI_Finalize() explicitly outside of these calls.
>
>    This means that PetscFinalize() should leave the data in the code in an
> equivalent  state as before the first PetscInitialize() is called.
>
>     I just spent a couple hours banging my head against the wall due to
> two static variables in a function placed there on the assumption that
> PETSc was not reentrant.
>
>     Please use static inside PETSc functions very carefully (if ever) and
> make sure they don't destroy the reentrancy.
>
>     Thanks
>
>      Barry
>
>
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