> On Feb 1, 2023, at 9:17 PM, Matthew Knepley <knep...@gmail.com> wrote: > > On Wed, Feb 1, 2023 at 9:06 PM Barry Smith <bsm...@petsc.dev > <mailto:bsm...@petsc.dev>> wrote: >> >> Hmm, When I do >> >> def somePythonfunction(): >> ... >> x = da.createLocalVec() >> .... >> return >> >> The x seems to be properly "garbage collected" at some point; I was >> guessing it was at the return or some time later than the return, but it did >> not wait until PetscFinalize(). >> >> So does the x above HAVE to exist until PetscFinalize()? If not then >> somehow Python realizes x is no longer referenced and VecDestroy() is called >> on it when some garbage collection takes place. I would like the same thing >> happen with the x = da.getLocalVec() but calling x.da.restoreLocalVec() >> instead of x.destroy(). Note specifically parallelism doesn't play a role >> here because x is local. > > It can happen at a random time, so it is unsafe to structure without a "with" > since it could hold the local vector maybe after the user tries to destroy > the DA.
Thanks. I am assuming you are talking about the getLocalVec() case. So it appears I need to dynamically attach an __exit__() method to the Vec in da.getLocalVec() so that restoreLocalVec() gets called https://www.geeksforgeeks.org/with-statement-in-python/ when the local vector goes out of scope of the with. I assume I can have multiple independent objects created with a with or I guess I could nest them when needed for local representations of u and du for TS.IFunction. I'll try tomorrow. Thanks again for pointing to the with construct. Barry > > Matt > >> Barry >> >> >>> On Feb 1, 2023, at 8:07 PM, Matthew Knepley <knep...@gmail.com >>> <mailto:knep...@gmail.com>> wrote: >>> >>> On Wed, Feb 1, 2023 at 6:33 PM Barry Smith <bsm...@petsc.dev >>> <mailto:bsm...@petsc.dev>> wrote: >>>> >>>> Would it be possible to rig the xlocal obtained from >>>> self.da.getLocalVec() to automatically trigger the da.restoreLocalVec() >>>> when the xlocal goes out of scope so that the user does not need to >>>> explicitly make the call. If so, how should I go about implementing it? >>> >>> This would work in C++ where the object has a defined lifetime, but Python >>> is garbage collected. The way it does this >>> pattern is using the "with" statement. >>> >>> Matt >>> >>>> Barry >>> -- >>> What most experimenters take for granted before they begin their >>> experiments is infinitely more interesting than any results to which their >>> experiments lead. >>> -- Norbert Wiener >>> >>> https://www.cse.buffalo.edu/~knepley/ <http://www.cse.buffalo.edu/~knepley/> >> > > > -- > What most experimenters take for granted before they begin their experiments > is infinitely more interesting than any results to which their experiments > lead. > -- Norbert Wiener > > https://www.cse.buffalo.edu/~knepley/ <http://www.cse.buffalo.edu/~knepley/>
