1843949 - Consider pre-allocating the attribute array based on the known attribute count from the parser

Status: RESOLVED FIXED

(Core :: DOM: HTML Parser, task)

Description

[Markus Stange [:mstange]]

Here's a profile of 33 iterations of the TodoMVC-jQuery subtest, focused on nsHtml5TreeOperation::SetHTMLElementAttributes: https://share.firefox.dev/3Dk2cvg

It shows some amount of time spent in AttrArray::GrowBy, suggesting that the attribute array might be grown and reallocated multiple times.

The parser knows the number of attributes it's going to add. I think it's worth pre-allocating the array to that known count.

I have a patch which does this; it doesn't help a huge amount on speedometer3 but it seems worth doing anyway.

Comment 1

[Markus Stange [:mstange]]

Attachment: Bug 1843949 - Preallocate attribute array with the known size from parsing. r=emilio

Comment 2

[Olli Pettay [:smaug][[e-mail]]]

This is basically bug 380802, but since this has a patch, marking that a dup of this one.

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/a1321f6af73b
Preallocate attribute array with the known size from parsing. r=emilio

Comment 5

[Sandor Molnar[:smolnar]]

https://hg.mozilla.org/mozilla-central/rev/a1321f6af73b