Bug 14977 – Hixie's DOM Core performance test shows insert >10x slower than append

• Status: RESOLVED
• Resolution: FIXED
• Component: DOM

[Darin Adler]

I noticed that the performance test indicated that insert was 10x slower than append.

Then I figured out why. Unnecessary churn in the NodeList code. I have a patch that fixes it, but it could possibly slow down other things so it's not quite ready for review.

I didn't make a regression test yet.

[Darin Adler]

Created attachment 15985 [details]
first cut at a fix

[Darin Adler]

Created attachment 15986 [details]
first cut at a fix (uploaded wrong the first time)

[Oliver Hunt]

Comment on attachment 15986 [details]
first cut at a fix (uploaded wrong the first time)

+private:
+    virtual bool nodeMatches(Node*) const;

private virtual?

Nothing else leaps out at me as being odd, but i don't feel qualified to comment on risk or correctness :(

My ad hoc benchmarking of this show Insertion time (from hixies DOM Core test) go from ~1100ms (avg. of 3 runs) to ~110ms (3 runs)

[Oliver Hunt]

Comment on attachment 15986 [details]
first cut at a fix (uploaded wrong the first time)

Okay, after repeated runs (mostly cleaning my tree) i don't think this is safe, it's a huge regression for the Indexd portion of Hixies DOM Core tests

[Oliver Hunt]

http://nontroppo.org/timer/Hixie_DOM.html

The index test goes from 26ms to >1000ms

[Alexey Proskuryakov]

Created attachment 17443 [details]
proposed fix

This doesn't cause regressions in other tests.

I couldn't fully understand the original patch, so I started from scratch. It's possible that I missed some additional optimization opportunities that were present there.

[Alexey Proskuryakov]

> Unnecessary churn in the NodeList code.

In other words, the problem had nothing to do with insertion performance - it's the previous test (index) that was making us register too many NodeLists, and thus slowed down subsequent DOM mutations.

[Maciej Stachowiak]

Comment on attachment 17443 [details]
proposed fix

r=me

[Alexey Proskuryakov]

Committed revision 27983.