[Python-Dev] Let's change to C API!

Victor Stinner vstinner at redhat.com
Tue Jul 31 12:25:25 EDT 2018

 I replied on capi-sig.

2018-07-31 18:03 GMT+02:00 Antoine Pitrou <solipsis at pitrou.net>:
> On Tue, 31 Jul 2018 15:34:05 +0200
> Victor Stinner <vstinner at redhat.com> wrote:
>> Antoine: would you mind to subscribe to the capi-sig mailing list? As
>> expected, they are many interesting points discussed here, but I would
>> like to move all C API discussions to capi-sig. I only continue on
>> python-dev since you started here (and ignored my request to start
>> discussing my idea on capi-sig :-)).
> Well, I responded to your e-mail discussion thread.  I see more
> messages in this thread here than on capi-sig. ;-)
>> For example, PyPy uses different memory allocators depending on the
>> scope and the lifetime of an object. I'm not sure that you can
>> implement such optimization if you are stuck with reference counting.
> But what does reference counting have to do with memory allocators
> exactly?
>> > OS vendors seem to be doing a fine job AFAICT.  And if I want a recent
>> > Python I just download Miniconda/Anaconda.
>> Is it used in production to deploy services? Or is it more used by
>> developers? I never used Anaconda.
> I don't know, but there's no hard reason why you couldn't use it to
> deploy services (though some people may prefer Docker or other
> technologies).
>> > I think you don't realize that the C API is *already* annoying.  People
>> > started with it mostly because there wasn't a better alternative at the
>> > time.  You don't need to make it more annoying than it already is ;-)
>> >
>> > Replacing existing C extensions with something else is entirely a
>> > developer time/effort problem, not an attractivity problem.  And I'm
>> > not sure that porting a C extension to a new C API is more reasonable
>> > than porting to Cython entirely.
>> Do you think that it's doable to port numpy to Cython? It's made of
>> 255K lines of C code.
> Numpy is a bit special as it exposes its own C API, so porting it
> entirely to Cython would be difficult (how do you expose a C macro in
> Cython?).  Also, internally it has a lot of macro-generated code for
> specialized loop implementations (metaprogramming in C :-)).
> I suppose some bits could be (re)written in Cython.  Actually, the
> numpy.random module is already a Cython module.
>> > It's just that I disagree that removing the C API will make CPython 2x
>> > faster.
>> How can we make CPython 2x faster? Why everybody, except of PyPy,
>> failed to do that?
> Because PyPy spent years working full time on a JIT compiler.  It's also
> written in (a dialect of) Python, which helps a lot with experimenting
> and building abstractions, compared to C or even C++.
> Regards
> Antoine.
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