On Sun, Oct 24, 2021 at 6:03 AM Bluenix <bluenix...@gmail.com> wrote: > > Hmm, I thought I responded to this on Gmail but it hasn't appeared here on > the archive so I'll send it again.. > > Is it known how much more/less the annotations impact performance compared to > function defaults? >
Basically, PEP 563 overhead is the same as function defaults. * Function annotations are one constant tuple per function. * Functions having the same signature share the same annotation tuple. * No GC overhead because it is constant (not tracked by GC). On the other hand, it is difficult to predicate PEP 649 overhead. When namespace is not kept: * Annotation is just a constant tuple too. * No GC overhead too. * The constant tuple will be slightly bigger than PEP 563. (It can be the same as PEP 563 when all annotations are constant.) * Although they are constant tuples, they may have their own names and firstlineno. So it is difficult to share whole annotation data between functions having the same signature. (*) (*) I proposed to drop firstlineno and names to share more annotations. See https://github.com/larryhastings/co_annotations/pull/9 When namespace is kept: * Annotations will be GC tracked objects. * They will be heavier than the "namespace is not kept", for both of startup time and memory consumption. * They have some GC overhead. To answer "how much more", we need a target application. But I don't have a good target application for now. Additionally, even if we have a good target application, it is still difficult to estimate real future impact. For example, SQLAlchemy has very heavy docstrings so the `-OO` option has a big impact. But SQLAlchemy doesn't use function annotations yet. So stock/PEP 563/PEP 649 have the same (zero) cost. Yay! But if SQLAlchemy starts using annotations, *all applications* using SQLAlchemy will be impacted in the future. Regards, -- Inada Naoki <songofaca...@gmail.com> _______________________________________________ Python-Dev mailing list -- python-dev@python.org To unsubscribe send an email to python-dev-le...@python.org https://mail.python.org/mailman3/lists/python-dev.python.org/ Message archived at https://mail.python.org/archives/list/python-dev@python.org/message/WHLQAVAXXXACUABGS2EJLYWU336ISZDD/ Code of Conduct: http://python.org/psf/codeofconduct/
