1329158 - Optimize maintaining scroll position in RequestListContent

Status: RESOLVED FIXED

(DevTools :: Netmonitor, defect, P1)

Description

[Jarda Snajdr [:jsnajdr]]

Profiling the React/Redux implemenation of Netmonitor UI with Cleopatra tells me that a lot of time is spent in RequestListContent.componentDidUpdate setting the node.scrollTop property. This scrolls the list to the bottom, and it's an expensive operation that triggers reflow.

My testing shows that it's performed twice as often than necessary. In approx half of the cases, the request list length didn't change, so updating the scroll position is not needed.

Comment 1

[Jarda Snajdr [:jsnajdr]]

Attachment: Bug 1329158 - Optimize maintaining scroll position in RequestListContent

Review commit: https://reviewboard.mozilla.org/r/102902/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/102902/

Comment 2

[Jarda Snajdr [:jsnajdr]]

The patch does two things:
- when determining "shouldScrollToBottom", check if the request list size is increasing for this update
- drive-by improvement of "setScalingStyles": the "currentScale" value doesn't need to be stored - can be computed from prevProps

Comment 3

[Jan Honza Odvarko [:Honza] (always need-info? me)]

Comment on attachment 8824376 [details]
Bug 1329158 - Optimize maintaining scroll position in RequestListContent

https://reviewboard.mozilla.org/r/102902/#review103372

LGTM, thanks Jarda!

Honza

Comment 4

[Jarda Snajdr [:jsnajdr]]

Try is green, going to land:

https://treeherder.mozilla.org/#/jobs?repo=try&revision=d1ebbfe40a3d64f832b340395c549fdbe69a4cf1

I'll be investigating what performance improvements are really visible in talos.

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/6556dab689a6
Optimize maintaining scroll position in RequestListContent r=Honza

Comment 6

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/6556dab689a6