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Re: [whatwg] Canvas-Only Document Type

From: Boris Zbarsky <bzbarsky@MIT.EDU>
Date: Mon, 07 Jul 2014 21:47:47 -0400
Message-ID: <53BB4DC3.70502@mit.edu>
To: whatwg@lists.whatwg.org
On 7/7/14, 6:58 PM, Brian M. Blakely wrote:
> I am not a browser developer, I am a Web developer, but it stands to reason that (as stated in the OP) there may at least be a fruitful memory savings

I just measured in Firefox 30, and a bare-bones document (about:blank) 
uses approximately 550KB of memory.

This breaks down as about:

* 330KB of JS heap (which presumably would be there anyway for your
   special document),
* 10KB DOM data structures
* 210KB layout data (mostly style data, looks like).

So you could plausibly save about 220KB of memory.  I encourage you to 
do similar measurements in other browsers as desired.

For comparison, a 320x426 canvas (and I doubt you're going to be using 
ones smaller than that in this special mode) will have a backing store 
that takes about 545KB for a 2D canvas.  The sort of devices where 
you're likely to actually use WebGL will probably have 4MB+ canvas 
backing stores, and probably comparable for WebGL.


> On the memory front, this could be especially useful when sharing space with the 30+ tabs

That would translate into a savings of about 7MB.  Not nothing, but just 
to put that in perspective simply loading 
http://code.jquery.com/jquery-1.11.1.min.js into those blank tabs above 
makes them use 1.43MB of memory instead of 550KB.  That's without 
_doing_ anything; just loading the library.

So I suspect in practice the script state and canvas backing stores in 
those 30+ tabs would totally swamp the 7MB of layout/DOM data.

-Boris
Received on Tuesday, 8 July 2014 01:48:15 UTC

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