[Python-Dev] More compact dictionaries with faster iteration

[Maciej Fijalkowski]

Hello everyone.

Thanks raymond for writing down a pure python version ;-)

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. Again, while I tried, the approach is
not scientific at all, but unless someone points a clear flaw in the
code (it's in pypy/rlib/dict.py in rdict-experiments branch), I'm
probably abandoning this for now.

Cheers,
fijal