[Python-Dev] Tunable parameters in dictobject.c (was dictnotes.txt out of date?)

[Raymond Hettinger]

On Jun 13, 2012, at 2:37 PM, Mark Shannon wrote:

> I think that for combined tables a growth factor of x2 is best,
> but I don't have any hard evidence to back that up.


I believe that change should be reverted.  
You've undone work that was based on extensive testing and timings of many python apps.
In particular, it harms the speed of building-up all large dictionaries,
and it greatly harms apps with steady-size dictionaries with changing keys.

The previously existing parameter were well studied
and have been well-reviewed by the likes of Tim Peters.
They shouldn't be changed without deep thought and study.
Certainly, "I think a growth factor of x2 is best" is insufficient.


Raymond

P.S.  In the tracker discussion of key-sharing dict, you were asked
to NOT change the tunable parameters.  I'm not sure why you
went ahead and did it anyway.
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