[Python-Dev] file.readinto performance regression in Python 3.2 vs. 2.7?

[Eli Bendersky]

On Thu, Nov 24, 2011 at 20:29, Antoine Pitrou <solipsis at pitrou.net> wrote:

> On Thu, 24 Nov 2011 20:15:25 +0200
> Eli Bendersky <eliben at gmail.com> wrote:
> >
> > Oops, readinto takes the same time as copying. This is a real shame,
> > because readinto in conjunction with the buffer interface was supposed to
> > avoid the redundant copy.
> >
> > Is there a real performance regression here, is this a well-known issue,
> or
> > am I just missing something obvious?
>
> Can you try with latest 3.3 (from the default branch)?
>

Sure. Updated the default branch just now and built:

$1 -m timeit -s'import fileread_bytearray' 'fileread_bytearray.justread()'
1000 loops, best of 3: 1.14 msec per loop
$1 -m timeit -s'import fileread_bytearray'
'fileread_bytearray.readandcopy()'
100 loops, best of 3: 2.78 msec per loop
$1 -m timeit -s'import fileread_bytearray' 'fileread_bytearray.readinto()'
1000 loops, best of 3: 1.6 msec per loop

Strange. Although here, like in python 2, the performance of readinto is
close to justread and much faster than readandcopy, but justread itself is
much slower than in 2.7 and 3.2!

Eli
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