Bug 47316 - HTML parser should use lazyAttach
Summary: HTML parser should use lazyAttach
Status: NEW
Alias: None
Product: WebKit
Classification: Unclassified
Component: New Bugs (show other bugs)
Version: 528+ (Nightly build)
Hardware: Other OS X 10.5
: P2 Normal
Assignee: Eric Seidel (no email)
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2010-10-06 17:59 PDT by Adam Barth
Modified: 2011-05-28 07:42 PDT (History)
4 users (show)

See Also:


Attachments
experiment (2.51 KB, patch)
2010-10-06 18:00 PDT, Adam Barth
no flags Details | Formatted Diff | Diff

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Description Adam Barth 2010-10-06 17:59:49 PDT
HTML parser should use lazyAttach
Comment 1 Adam Barth 2010-10-06 18:00:11 PDT
Created attachment 70020 [details]
experiment
Comment 2 Adam Barth 2010-10-06 18:11:02 PDT
Initial testing shows this as a loss:

== before ==

Running 20 times
Ignoring warm-up run (3278)
2729
2737
2722
2710
2745
2734
2725
2731
2749
2737
2735
2770
2754
2743
2747
2773
2762
2751
2771
2780

avg 2745.25
stdev 18.2944663764757

== after ==


Running 20 times
Ignoring warm-up run (3087)
2805
2810
2807
2801
2817
2830
2826
2812
2821
2846
2838
2828
2829
2862
2856
2845
2844
2848
2875
2864

avg 2833.2
stdev 20.894018282752604

Thoughts?
Comment 3 Eric Seidel (no email) 2010-10-13 11:05:10 PDT
I suspect our lazyAttach logic needs to be made more efficient before we use it.
Comment 4 Eric Seidel (no email) 2010-10-13 11:05:53 PDT
I suspect our lazyAttach logic needs to be made more efficient before we use it.
Comment 5 Pratik Solanki 2011-01-18 22:30:54 PST
I don't see a perf loss with this patch anymore, maybe even a slight win (?). On my quad-core iMac, I see

== before ==

Running 20 times
Ignoring warm-up run (802)
799
822
823
804
802
801
802
808
805
804
804
805
808
806
812
805
809
809
811
809

avg 807.4
median 805.5
stdev 6.011655346075654
min 799
max 823

== after ==

Running 20 times
Ignoring warm-up run (811)
815
817
801
800
794
801
797
796
799
796
798
801
798
802
803
801
802
811
803
803

avg 801.9
median 801
stdev 5.864298764558298
min 794
max 817
Comment 6 Adam Barth 2011-05-27 17:21:38 PDT
This is more Eric's department than mine.
Comment 7 Dimitri Glazkov (Google) 2011-05-28 07:42:59 PDT
lazyAttach will show as profitable only on some cases, right? It's useful when there are lots of attach-inducing changes in a given bit of time, and lazyAttach helps batching up these changes. So the maximum win will be in large chunk of script, which sparsely makes changes to DOM -- the lazyAttach saves you multiple re-traversals of the tree.

In the case of parser, you already do the batching, since _all_ of the parser DOM modifications are attachment-related. So I don't think the parser will ever see a significant win in lazyAttach.

However, we should still make this change in an effort to get rid of non-lazy attach().

http://www.youtube.com/watch?v=kq4SqgxIKM0