[Python-Dev] A new dictionary implementation

Mark Shannon mark at hotpy.org
Fri Feb 17 14:35:19 CET 2012

On 15/02/12 21:09, Yury Selivanov wrote:
> Hello Mark,
> First, I've back-ported your patch on python 3.2.2 (which was relatively
> easy).  Almost all tests pass, and those that don't are always failing on
> my machine if I remember.  The patch can be found here: http://goo.gl/nSzzY
> Then, I compared memory footprint of one of our applications (300,000 LOC)
> and saw it about 6% less than on vanilla python 3.2.2 (660 MB of reserved
> process memory compared to 702 MB; Linux Gentoo 64bit) The application is
> written in heavy OOP style (for instance, ~1000 classes are generated by our
> ORM on the fly, and there are approximately the same amount of hand-written
> ones) so I hoped for a much bigger saving.
> As for the patch itself I found one use-case, where python with the patch
> behaves differently::
>    class Foo:
>        def __init__(self, msg):
>            self.msg = msg
>    f = Foo('123')
>    class _str(str):
>        pass
>    print(f.msg)
>    print(getattr(f, _str('msg')))
> The above snippet works perfectly on vanilla py3.2, but fails on the patched
> one  (even on 3.3 compiled from your 'cpython_new_dict' branch)  I'm not sure
> that it's a valid code, though.  If not, then we need to fix some python
> internals to add exact type  check in 'getattr', in the 'operator.getattr', etc.
> And if it is - your  patch needs to be fixed.  In any case, I propose to add
> the above code to the  python test-suite, with either expecting a result or an
> exception.

Your code is valid, the bug is in my code.
I've fixed and updated the repository.
More tests to be added later.


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