capi-sig August 2018

capi-sig@python.org

10 participants
14 discussions

[capi-sig]Let's change to C API!
by Victor Stinner 03 Aug '18

03 Aug '18

Hi, Last year, I gave a talk at the Language Summit (during Pycon) to explain that CPython should become 2x faster to remain competitive. IMHO all attempts to optimize Python (CPython forks) have failed because they have been blocked by the C API which implies strict constraints. I started to write a proposal to change the C API to hide implementation details, to prepare CPython for future changes. It allows to experimental optimization ideas without loosing support for C extensions. C extensions are a large part of the Python success. They are also the reason why PyPy didn't replace CPython yet. PyPy cpyext remains slower than CPython because PyPy has to mimick CPython which adds a significant overhead (even if PyPy developers are working *hard* to optimize it). I created a new to discuss how to introduce backward incompatible changes in the C API without breaking all C extensions: http://pythoncapi.readthedocs.io/ The source can be found at: https://github.com/vstinner/pythoncapi/ I would like to create a team of people who want to work on this project: CPython, PyPy, Cython and anyone who depends on the C API. Contact me in private if you want to be added to the GitHub project. I propose to discuss on the capi-sig mailing list since I would like to involve people from various projects, and I don't want to bother you with the high traffic of python-dev. Victor PS: I added some people as BCC ;-)

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[capi-sig]Re: Adding an official (minimal) Cython-like tool.
by Jeroen Demeyer 03 Aug '18

03 Aug '18

On 2018-08-01 21:07, Robert Bradshaw wrote: > +1. There has been some of this, e.g. PEP 509 and and the ongoing > discussions with PEP 580. There could be more. There are also some unresolved issues in the import system: see https://bugs.python.org/issue32797 and https://github.com/python/cpython/pull/6653 It would be good to resolve that, as it seriously hampers development of Cython code on Python 3.

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[capi-sig]Replacing Python C API with CFFI
by Simon Cross 02 Aug '18

02 Aug '18

Hello! Summary: It looks like fixing the Python C API is a lot of work and might fail, so I was wondering if it would be better to put effort into reducing the C API by making more use of CFFI within the Python standard library instead? Motivation: * It feels like the C API is currently very broad because it provides a second interface layer to a large chunk of the Python object space (in addition to the one visible to Python code). * I think it was Armin Rigo's observation when writing CFFI that there is a better API that already exists -- i.e. C types and function signatures. * If we're going to do a lot of work, would it not be better to push instead for moving towards CFFI as the interface between C and Python? I'm not sure that this is orthogonal to Victor's current proposal or not -- it might just be one route to achieving it. Advantages over the current route: * There's a clearer direction for people to head it, so it's easier to contribute. * A lot of work has already been done (e.g. it works for PyPy, a lot of libraries already exist that use it). Maybe Cython is an equally good option to CFFI in this scenario -- I don't know Cython though, so I have no deep opinion on that. Schiavo Simon

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[capi-sig]Re: Adding an official (minimal) Cython-like tool.
by Jeroen Demeyer 02 Aug '18

02 Aug '18

On 2018-08-01 21:07, Robert Bradshaw wrote: > Herein lies the primary difficulty with option #3. I have a hard time > imagining what a low-level, minimal-ish "core" of Cython would be. > What features would be omitted or simplifications would be made? > > In addition, I'm concerned that putting a barrier somewhere in the > middle of the existing Cython project, with one half in third-party > and the other part of CPython, would significantly harm development > velocity and make adoption and distribution more difficult. +1 I don't think that distutils + setuptools is a good example to follow.

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capi-sig August 2018