Bug 99428 – [Shadow DOM][V8] WebCore::V8DOMWindow::installPerContextProperties() is slow when shadowDOMEnabled flag is on.

• Status: RESOLVED
• Resolution: FIXED
• Component: HTML Editing

[Hajime Morrita]

This upstreams http://code.google.com/p/chromium/issues/detail?id=155620
A profiling unveiled that this installPerContextProperties() is slower if the flag is on.
It makes sense since it injects extra DOMWindow properties at runtime.

My assumption is that installPerContextProperties() is called only a few times per page.
But there are some outliers in page cycler suite which consume 1.3% time in this function for each page load. 

I'll make some micro-benchmark for this.

[Hajime Morrita]

Basically there are two approaches to fix this.

A. Stop using EnablePerContext: Considering Chromium make it available for the wild Web, 
    The Shadow DOM feature does no longer need to be contextual. 
B. Make EnablePerContext faster somehow. I have no concrete idea yet. But maybe we should do this
    for other features which uses this contextual switch mechanism.

My feeling is that we can land A first then attack B if possible.

[Dimitri Glazkov (Google)]

(In reply to comment #1)
> My feeling is that we can land A first then attack B if possible.

That sounds good.

[Hajime Morrita]

Created attachment 169079 [details]
Patch

[Hajime Morrita]

Created attachment 169085 [details]
Patch for landing

[WebKit Review Bot]

Comment on attachment 169085 [details]
Patch for landing

Clearing flags on attachment: 169085

Committed r131549: <http://trac.webkit.org/changeset/131549>

[WebKit Review Bot]

All reviewed patches have been landed.  Closing bug.