[Python-Dev] Benchmarks why we need PEP 576/579/580

[Ivan Pozdeev]

I think it'll benefit all to keep the discussion objective, or at least 
"good subjective" 
(https://stackoverflow.blog/2010/09/29/good-subjective-bad-subjective/). 
Laments or mutual accusations are only wasting everyone's time, 
including the writers.
It's strange that even Guido jumped on the bandwagon -- since he's 
supposed to have had lots of experience to tell right away when a 
discussion has become unproductive. (Or maybe he's testing us?)


All the material to discuss that we have in this thread is a single test 
result that's impossible to reproduce and impossible to run in Py3.

All that this shows is that the PEPs will _likely_ substantially improve 
performance in some scenarios. It's however impossible to say from this 
how frequent these scenarios are in practice, and how consistent the 
improvement is among them. Likewise, it's impossible to say anything 
about the complexity the changes will reduce/introduce without a 
proof-of-concept implementation. So while this is an argument in favor 
of the PEPs, it's too flimsy _on its own_ to accept anything. More and 
better tests and/or sample implementations are needed to say anything 
more conclusive.

All that was already pointed out, and that's where the thread should 
have ended IMO 'cuz there's nothing else to say on the matter.


On 23.07.2018 1:28, Guido van Rossum wrote:
> On Sun, Jul 22, 2018 at 1:11 PM, Jeroen Demeyer <J.Demeyer at ugent.be 
> <mailto:J.Demeyer at ugent.be>> wrote:
>
>     On 2018-07-22 14:52, Stefan Behnel wrote:
>
>         Someone has to maintain the *existing* code
>         base and help newcomers to get into it and understand it.
>
>
>     This is an important point that people seem to be overlooking. The
>     complexity and maintenance burden of PEP 580 should be compared to
>     the status-quo. The existing code is complicated, yet nobody seems
>     to find that a problem. But when PEP 580 makes changes to that
>     complicated code (and documents some of the existing complexity),
>     it's suddenly the fault of PEP 580 that the code is complicated.
>
>     I also wonder if there is a psychological difference simply
>     because this is a PEP and not an issue on bugs.python.org
>     <http://bugs.python.org>. That might give the impression that it's
>     a more serious thing somehow. Previous optimizations
>     (https://bugs.python.org/issue26110
>     <https://bugs.python.org/issue26110> for example) were not done in
>     a PEP and nobody ever mentioned that the extra complexity might be
>     a problem.
>
>     Finally, in some ways, my PEP would actually be a simplification
>     because it replaces several special cases by one general protocol.
>     Admittedly, the general protocol that I propose is more
>     complicated than each existing special case individually but the
>     overall complexity might actually decrease.
>
>
> So does your implementation of the PEP result in a net increase or 
> decrease of the total lines of code? I know that that's a poor proxy 
> for complexity (we can all imagine example bits of code that would 
> become less complex by rewriting them in more lines), but if your diff 
> actually deleted more lines than it adds, that would cut short a lot 
> of discussion. I have a feeling though that that's not the case, and 
> now you're in the defense.
>
> -- 
> --Guido van Rossum (python.org/~guido <http://python.org/%7Eguido>)
>
>
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-- 
Regards,
Ivan

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