[Python-Dev] Tunable parameters in dictobject.c (was dictnotes.txt out of date?)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

"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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