Message 310604 - Python tracker

Message310604

Author	methane
Recipients	methane, serhiy.storchaka, vstinner, yselivanov
Date	2018-01-24.16:02:09
SpamBayes Score	-1.0
Marked as misclassified	Yes
Message-id	<1516809729.57.0.467229070634.issue32623@psf.upfronthosting.co.za>
In-reply-to

Content
> * When dict size become 0, make the dict shared-empty, like dict.clear() This will cause significant performance regression for `dict[a]=None; del dict[a]` loop. del/pop shouldn't do clear(). > * When (dict size < dk_size/8), call insertion_resize() This is bad too. When ma_used=127 and dk_size=1024, new size will be 1024! It's because current GROWTH_RATE is used*2 + size/2. This GROWTH_RATE is set in issue17563. We should understand it before changing anything.

Content

> * When dict size become 0, make the dict shared-empty, like dict.clear()

This will cause significant performance regression for `dict[a]=None; del dict[a]` loop.
del/pop shouldn't do clear().

> * When (dict size < dk_size/8), call insertion_resize()

This is bad too.
When ma_used=127 and dk_size=1024, new size will be 1024!
It's because current GROWTH_RATE is used*2 + size/2.

This GROWTH_RATE is set in issue17563.
We should understand it before changing anything.

History
Date	User	Action	Args
2018-01-24 16:02:09	methane	set	recipients: + methane, vstinner, serhiy.storchaka, yselivanov
2018-01-24 16:02:09	methane	set	messageid: <1516809729.57.0.467229070634.issue32623@psf.upfronthosting.co.za>
2018-01-24 16:02:09	methane	link	issue32623 messages
2018-01-24 16:02:09	methane	create