Bug 103571 – some checkReplaceChild() can be skipped if there are no event listener fired.

• Status: NEW
• Component: DOM

[Hajime Morrita]

Suggested at Bug 103372.

ContainerNode::replaceChild() calls multiple checkReplaceChild() for preventing manifold tree.
But we can skip the one other than the first if we know there is no event listener fired since the last checkReplaceChild() call.
That omission will improve replaceChild() performance.

[Hajime Morrita]

Created attachment 176693 [details]
Patch

[Hajime Morrita]

I tried, but didn't go faster and went even slower. It looks our fast path does fast enough.
I'd close this bug unless there are something I overlooked.

[Ojan Vafai]

What did you use to measure performance here? The main performance bottleneck in checkAcceptChild I think is the contains call, which is O(n) in the depth of the tree. I would expect a test case with a deep tree to show improvement.

[Hajime Morrita]

(In reply to comment #3)
> What did you use to measure performance here? The main performance bottleneck in checkAcceptChild I think is the contains call, which is O(n) in the depth of the tree. I would expect a test case with a deep tree to show improvement.

Ah, that's right. What I used is dom-modify. We need some better benchmark here.

[Kentaro Hara]

(In reply to comment #4)
> We need some better benchmark

We're always saying this:D

[Ojan Vafai]

(In reply to comment #5)
> (In reply to comment #4)
> > We need some better benchmark
> 
> We're always saying this:D

lol. It's always true!

I don't think that the benchmarks we have generally don't test deep DOM trees, so we don't get good performance testing of things that are O(n) in DOM depth.