[Python-Dev] Tunable parameters in dictobject.c (was dictnotes.txt out of date?)

"Martin v. Löwis" martin at v.loewis.de
Mon Jun 18 09:20:09 CEST 2012


> The default should be what we've had though.
> The new settings cause a lot more collisions
> and resizes.

Raymond, can you kindly point to an application that demonstrates this
claim (in particular the "a lot more" part, which I'd translate to
"more than 20% more").

I'm fine with reverting changes, but I agree that any benchmarking
performed should be repeatable, and public. I agree it's sad to see
a month worth of benchmarking reverted - but had that benchmarking
been documented publicly, rather than just reporting the outcome,
such reversal might have been avoided.

> Dicts get their efficiency from sparseness.
> Reducing the mindict size from 8 to 4 causes
> substantially more collisions in small dicts
> and gets closer to a linear search of a small tuple.

Why do you think the dictsize has been reduced from 8 to 4? It has not.

Regards,
Martin


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