[Webkit-unassigned] [Bug 10773] Memory usage grows when reloading google.com/ig

[bugzilla-daemon at webkit.org]

http://bugs.webkit.org/show_bug.cgi?id=10773





------- Comment #18 from sanjay12 at gmail.com  2007-01-16 11:52 PDT -------
Please ignore everything I wrote prior to the "Browsing the code" line, I typed
up that message over the course of a long time going back and forth, that I
didn't realize the first few sentences completely contradicted what I talk
about later on :P.

(In reply to comment #17)
> Browsing the code some more, I'm curious (though I can't really test it until I
> get home) whether the issue is maybe something like this:
> 
> 1. You hit refresh, and a new HTMLDocument is created.
> 2. The new HTMLDocument adopts the previous document's HTMLBodyElement or
> HTMLHeadElement, for whatever reason (it maybe needs to be kept alive
> temporarily on the refresh to make sure onunload handlers get their chance to
> run).
> 3. However, even though the old HTMLBodyElement or old HTMLHeadElement is now
> adopted by the new HTMLDocument, it STILL has a reference to the old
> HTMLDocument in it's node tree.
> 4. So now when the old HTMLBodyElement/HeadElement gets marked, even though
> it's now owned by the new HTMLDocument, it marks the old HTMLDocument because
> it still has a reference to it in its tree.
> 5. Now that the old HTMLDocument is marked, its destructor can never be called.
> This is important because it means forgetAllDOMNodesForDocument never gets
> called, which then leaks the old HTMLDocument + any DOM Nodes that weren't
> adopted by the new HTMLDocument
> 6. Then the vicious cycle continues for every subsequent refresh.
> 
> 
> This might also explain why in the case of bdash's simplification without the
> window event handlers, if you never press a key and just click the refresh
> button, you don't leak. The reason for this is since the "keydown" listener
> isn't being processesed, the old HTMLHead doesn't need to be kept alive. The
> "keydown" listener is accessing the HTMLHead, so if a key is being pressed
> (which happens when you Cmd-R) when you refresh, the HTMLHead gets adopted by
> the new document, and causing the pattern as described above.
> 
> So then the "fix" if this is what's happening is to make sure that in
> updateDOMNodeDocument, it traverses through the tree and breaks off any links
> to the old HTMLDocument.
> 
> *Note the above comments were from information not actually garnered while
> debugging, so it's certainly feasible that I'm totally off-base here!
> 


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