[Python-Dev] Tunable parameters in dictobject.c (was dictnotes.txt out of date?)

[Raymond Hettinger]

On Jun 14, 2012, at 4:32 AM, Kristján Valur Jónsson wrote:

>  I would like to two or more compile time
> settings to choose from:  Memory optimal, speed optimal, (and mix).

A compile time option would be nice.

The default should be what we've had though.
The new settings cause a lot more collisions
and resizes.  The resizes themselves have more
collisions than before (there are few collisions
when resizing into a quadrupled dict than into
a doubled dict).  

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.


Raymond
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