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Re: On-topic: alternate Python implementations

From Stefan Behnel <stefan_ml@behnel.de>
Subject Re: On-topic: alternate Python implementations
Date 2012-08-05 07:37 +0200
References (2 earlier) <501cff63$0$29978$c3e8da3$5496439d@news.astraweb.com> <mailman.2930.1344079082.4697.python-list@python.org> <7x1ujmabs9.fsf@ruckus.brouhaha.com> <501dc461$0$29978$c3e8da3$5496439d@news.astraweb.com> <7x1ujm9kyu.fsf@ruckus.brouhaha.com>
Newsgroups comp.lang.python
Message-ID <mailman.2957.1344145080.4697.python-list@python.org> (permalink)

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Paul Rubin, 05.08.2012 03:38:
> Steven D'Aprano writes:
>> Runtime optimizations that target the common case, but fall back to 
>> unoptimized code in the rare cases that the optimization doesn't apply, 
>> offer the opportunity of big speedups for most code at the cost of 
>> trivial slowdowns when you do something unusual.
> 
> The problem is you can't always tell if the unusual case is being
> exercised without an expensive dynamic check, which in some cases must
> be repeated in every iteration of a critical inner loop, even though it
> turns out that the program never actually uses the unusual case.

Cython does a lot of optimistic optimisations. That's where a large part of
that huge C file comes from that Cython generates from even simple Python code.

For example, in CPython, C function calls are so ridiculously faster than
Python function calls that it's worth some effort if it saves you from
packing an argument tuple to call into a Python function. In fact, we've
been thinking about ways to export C signatures from Python function
objects, so that code implemented in C (or a C compatible language) can be
called directly from other code implemented in C. That's very common in the
CPython ecosystem.

There are a lot of simple things that quickly add up into a much better
performance on average.

Stefan

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Thread

On-topic: alternate Python implementations Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-08-04 06:15 +0000
  Re: On-topic: alternate Python implementations Chris Angelico <rosuav@gmail.com> - 2012-08-04 16:34 +1000
    Re: On-topic: alternate Python implementations Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-08-04 10:54 +0000
      Re: On-topic: alternate Python implementations Stefan Krah <stefan-usenet@bytereef.org> - 2012-08-04 13:18 +0200
        Re: On-topic: alternate Python implementations Paul Rubin <no.email@nospam.invalid> - 2012-08-04 08:59 -0700
          Re: On-topic: alternate Python implementations Stefan Behnel <stefan_ml@behnel.de> - 2012-08-04 18:55 +0200
            Re: On-topic: alternate Python implementations Paul Rubin <no.email@nospam.invalid> - 2012-08-04 11:18 -0700
              Re: On-topic: alternate Python implementations Stefan Behnel <stefan_ml@behnel.de> - 2012-08-04 21:06 +0200
                Re: On-topic: alternate Python implementations Paul Rubin <no.email@nospam.invalid> - 2012-08-04 13:43 -0700
                Re: On-topic: alternate Python implementations Stefan Behnel <stefan_ml@behnel.de> - 2012-08-04 23:24 +0200
              Re: On-topic: alternate Python implementations MRAB <python@mrabarnett.plus.com> - 2012-08-04 20:24 +0100
          Re: On-topic: alternate Python implementations Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-08-05 00:54 +0000
            Re: On-topic: alternate Python implementations Paul Rubin <no.email@nospam.invalid> - 2012-08-04 18:38 -0700
              Re: On-topic: alternate Python implementations Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-08-05 02:19 +0000
                Re: On-topic: alternate Python implementations John Nagle <nagle@animats.com> - 2012-08-06 22:57 -0700
              Re: On-topic: alternate Python implementations Stefan Behnel <stefan_ml@behnel.de> - 2012-08-05 07:37 +0200
            Re: On-topic: alternate Python implementations Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2012-08-04 23:09 -0400
      Re: On-topic: alternate Python implementations Stefan Behnel <stefan_ml@behnel.de> - 2012-08-04 13:32 +0200
  Re: On-topic: alternate Python implementations Stefan Behnel <stefan_ml@behnel.de> - 2012-08-04 08:40 +0200
    Re: On-topic: alternate Python implementations Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-08-04 07:49 +0000
      Re: On-topic: alternate Python implementations Stefan Behnel <stefan_ml@behnel.de> - 2012-08-04 11:10 +0200
        Re: On-topic: alternate Python implementations Thomas Rachel <nutznetz-0c1b6768-bfa9-48d5-a470-7603bd3aa915@spamschutz.glglgl.de> - 2012-08-04 14:51 +0200
          Re: On-topic: alternate Python implementations Stefan Behnel <stefan_ml@behnel.de> - 2012-08-04 15:53 +0200
            Re: On-topic: alternate Python implementations Ulrich Eckhardt <ulrich.eckhardt@dominolaser.com> - 2012-08-08 10:29 +0200
          Re: On-topic: alternate Python implementations Stefan Behnel <stefan_ml@behnel.de> - 2012-08-04 16:03 +0200
      Re: On-topic: alternate Python implementations Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-08-04 11:05 +0100
      Re: On-topic: alternate Python implementations Stefan Behnel <stefan_ml@behnel.de> - 2012-08-04 12:59 +0200
      Re: On-topic: alternate Python implementations Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-08-04 19:24 +0100
        Re: On-topic: alternate Python implementations Temia Eszteri <lamialily@cleverpun.com> - 2012-08-04 11:34 -0700
        Re: On-topic: alternate Python implementations Ben Finney <ben+python@benfinney.id.au> - 2012-08-06 01:21 +1000
      Re: On-topic: alternate Python implementations Zero Piraeus <schesis@gmail.com> - 2012-08-04 14:42 -0400
      Re: On-topic: alternate Python implementations Zero Piraeus <schesis@gmail.com> - 2012-08-04 14:56 -0400
      Re: On-topic: alternate Python implementations Ethan Furman <ethan@stoneleaf.us> - 2012-08-05 07:27 -0700
  Re: On-topic: alternate Python implementations Tim Roberts <timr@probo.com> - 2012-08-04 13:07 -0700
  Re: On-topic: alternate Python implementations jwp <james.pye@gmail.com> - 2012-08-04 15:05 -0700
  Re: On-topic: alternate Python implementations Jürgen A. Erhard <jae+python@jaerhard.com> - 2012-08-05 01:25 +0200
  Re: On-topic: alternate Python implementations Stefan Behnel <stefan_ml@behnel.de> - 2012-08-05 07:46 +0200
  Re: On-topic: alternate Python implementations Stefan Behnel <stefan_ml@behnel.de> - 2012-08-05 09:51 +0200
  Re: On-topic: alternate Python implementations Jürgen A. Erhard <jae+python@jaerhard.com> - 2012-08-05 14:28 +0200
  Re: On-topic: alternate Python implementations alex23 <wuwei23@gmail.com> - 2012-08-05 20:40 -0700
    Re: On-topic: alternate Python implementations Stefan Behnel <stefan_ml@behnel.de> - 2012-08-06 08:21 +0200
  Re: On-topic: alternate Python implementations Stefan Behnel <stefan_ml@behnel.de> - 2012-08-06 08:46 +0200
  Alternate Python extensions (was alternate Python implementations) rusi <rustompmody@gmail.com> - 2012-08-06 21:23 -0700
    Re: Alternate Python extensions (was alternate Python implementations) Stefan Behnel <stefan_ml@behnel.de> - 2012-08-07 07:09 +0200

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