614163 - Slow property access on dromaeo's "jQuery -attr(class) x 100" benchmark

Status: RESOLVED INCOMPLETE

(Core :: JavaScript Engine, defect)

Description

[Boris Zbarsky [:bzbarsky]]

This is in the "DOM Attributes (jQuery)" section in dromaeo.  Nearly 20% of the time is dealing with resolves (due to JM not PICing DOM stuff with getters?) and in particular calling XPC_WN_ModsAllowed_ProtoResolve is about 10% of the total time.  Peter, is that used for just normal DOM objects too?

Comment 1

[John-David Dalton]

Something to keep in mind is Dromaeo is using jQuery v1.2.3.
http://docs.jquery.com/Release:jQuery_1.2.3 from February 2008.

Comment 2

[Boris Zbarsky [:bzbarsky]]

Yes, but it's just using the DOM.  A newer jquery may use the DOM slightly differently, but it may not....

Or do you have concrete evidence the attr() has been significantly changed since in a way that makes this bug somehow irrelevant to our DOM performance?

Comment 3

[John-David Dalton]

DOM performance is important regardless of JS lib or lib version so please keep digging/investigating for perf improvements. 
jQuery did do an overhaul of their attribute/property related methods in v1.6
http://blog.jquery.com/2011/05/03/jquery-16-released/

Comment 4

[(no longer active)]

Marking [qf:investigate:p1] so that someone would first investigate whether this is still an issue.

Comment 5

[Andrew McCreight [:mccr8]]

I don't think a DOM bindings perf issue from 2010 is likely still relevant. For instance, we're not using XPConnect for normal web stuff so XPC_WN_ModsAllowed_ProtoResolve shouldn't be relevant.