[webkit-dev] RenderArena: Teaching an old dog new tricks

Chris Evans cevans at chromium.org
Thu Nov 15 02:08:24 PST 2012

On Thu, Nov 15, 2012 at 12:34 AM, Elliott Sprehn <esprehn at chromium.org>wrote:

> On Thu, Nov 15, 2012 at 3:22 AM, Chris Evans <cevans at chromium.org> wrote:
>>> ...
>> My read on the Arena is that it's fragmentation resistant (i.e. it will
>> not repurpose a larger free chunk to satisfy a smaller allocation.)
>> However, memory usage at any given time is defined by peak usage since it
>> cannot release pages back to the system without ruining its security
>> guarantee. Interestingly, it can't be super bad: we already bite this
>> bullet for RenderArena as used by RenderObjects. The RenderArena lifetime
>> is the same as the document / DOM and I was surprised to recently be told
>> that we don't throw away the RenderArena on a full layout.
> My understanding is that the render tree is rather small compared to the
> DOM in terms of memory usage on most pages

This does not seem to necessarily be the case.

Loading Gmail to the inbox view, sizes in bytes for all live allocations:
- 541k in the DOM arena
- At least a 918k plus a 49k render arena. May have failed to count a few
smaller ones that are still live.

Would you like similar measurements for a simpler page? Or some other
complicated page you think might be instructive?


so not releasing it may not be so bad, but never releasing the memory used
> from DOM nodes seems like it'd be bad for large web apps.
> - E
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