[webkit-dev] Performance of NamedAttrMap

Yaar Schnitman yaar at chromium.org
Thu Oct 29 14:57:37 PDT 2009

I encountered a similar (potential) performance problem with style
properties (see CSSMutableStyleDeclaration::findPropertyWithId), which are
stored in an unordered vector too.

A potential solution would be to create a HashMap only for elements / style
properties with more than K (5+?) attributes,  and only when they are first
accessed. Such a hashmap will not replace the vector, but just provide an
index to it.

On Thu, Oct 29, 2009 at 2:33 PM, Darin Adler <darin at apple.com> wrote:

> On Oct 29, 2009, at 2:32 PM, Darin Adler wrote:
>  On Oct 29, 2009, at 2:30 PM, Jens Alfke wrote:
>>   Is there any reason this couldn't be optimized to use a HashMap
>> Memory consumption is much greater.
>>  or at least binary search?
>> Would make lookups faster but parsing slower.
> I forgot to mention:
> I believe the common case for attributes is a very small number of
> attributes. Having one element with many attributes is quite uncommon. This
> is one consideration when making improvements and optimizations here. Making
> sure the pathological case is not terribly slow is good, but we also want
> the normal case to be super-fast.
>    -- Darin
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