[Python-Dev] More compact dictionaries with faster iteration

[Raymond Hettinger]

On Jan 3, 2013, at 2:22 AM, Maciej Fijalkowski <fijall at gmail.com> wrote:

> Hello everyone.
> 
> Thanks raymond for writing down a pure python version ;-)

Thanks for running with it.

> 
> I did an initial port to RPython for experiments. The results (on
> large dicts only) are inconclusive - it's either a bit faster or a bit
> slower, depending what exactly you do. There is a possibility I messed
> something up too (there is a branch rdict-experiments in PyPy, in a
> very sorry state though).
> 
> One effect we did not think about is that besides extra indirection,
> there is an issue with data locality - having to look in two different
> large lists seems to be a hit.

In pure python, I didn't see a way to bring the hash/key/value entries
side-by-side as they currently are in CPython.   How does PyPy currently
handle this issue?  Is there a change I could make to the recipe that
would restore data locality?


Raymond
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