1606514 - Faster visible-rows-only and pixel-aligned waterfall column

Status: VERIFIED FIXED

(DevTools :: Netmonitor, enhancement, P3)

Description

[:Harald Kirschner :digitarald]

Attachment: Before after ensuring minimum width boxes

Waterfall was the most expensive component, across the board (fetching additional eventTiming data, created React elements and CSS cost)

Part 1: Only show Waterfall only for visible rows

1. IntersectionObserver collects which rows are off screen as state
2. New elements register with the list observer and unregister later
3. Waterfall column is only rendered for visible rows and just an empty TD for the rest

Part 2: Scale Waterfall without transform

1. Waterfall isn't handled by CSS variables anymore (fixed expensive styling phase).
2. Using the newly gained CPU cycles RequestListColumnWaterfall now listens to the getWaterfallScale state and uses it to position the boxes to exact pixels.
3. Pixels ensure minimum width for boxes (fixes useless rendering of 0-width boxes; which end up showing a waterfall of mostly total time labels).

Miscellaneous fixes

• Taller boxes (closer to Chrome)
• Fixes layout jitter that rendering waterfall causes (the text added 0.5px height difference is my guess)
• Vertically aligned waterfall bars and labels (were slightly off center previously)

Profile comparison (16 to 11ms overall, much more responsive UI with more frequent updates): https://perfht.ml/2rIJJHE

Comment 1

[:Harald Kirschner :digitarald]

Attachment: Bug 1606514 - Faster visible-rows-only and pixel-aligned waterfall column r=honza,jlast

Comment 2

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

Attachment: visible-rows-tests.patch

Attaching a patch that fixes most of the test failures:
https://treeherder.mozilla.org/#/jobs?repo=try&revision=029d5dc022f684c330819feca9fac4d8289827d7&selectedJob=287940247

I am seeing just one test failure now:
devtools/client/webconsole/test/browser/browser_webconsole_network_messages_openinnet.js

I can't repro locally, needs some more investigation.

Honza

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/96965c8f4575
Faster visible-rows-only and pixel-aligned waterfall column r=Honza,jdescottes

Comment 4

[Dorel Luca [:dluca]]

Backed out changeset 96965c8f4575 (bug 1606514) for Talos failures in netmonitor/simple.js. CLOSED TREE

Log:
https://treeherder.mozilla.org/logviewer.html#/jobs?job_id=288992034&repo=autoland&lineNumber=932

Push with failures:
https://treeherder.mozilla.org/#/jobs?repo=autoland&group_state=expanded&revision=96965c8f4575078ce9a7412d0b904c1f3be63284

Backout:
https://hg.mozilla.org/integration/autoland/rev/b554f15005fbad3075e51922547321c0888c453f

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/10d15000963d
Faster visible-rows-only and pixel-aligned waterfall column r=Honza,jdescottes

Comment 6

[Stefan Hindli [:stefan_hindli]]

https://hg.mozilla.org/mozilla-central/rev/10d15000963d

Comment 7

[:Harald Kirschner :digitarald]

https://treeherder.mozilla.org/perf.html#/alerts?id=24959&hideDwnToInv=0

== Change summary for alert #24959 (as of Mon, 17 Feb 2020 03:48:26 GMT) ==

Regressions:

8% damp complicated.netmonitor.exportHar linux64-shippable-qr opt e10s stylo 847.45 -> 917.46
8% damp complicated.netmonitor.exportHar linux64-shippable opt e10s stylo 809.49 -> 870.42

Improvements:

38% damp simple.netmonitor.requestsFinished.DAMP windows10-64-shippable opt e10s stylo 140.09 -> 87.35
37% damp simple.netmonitor.requestsFinished.DAMP windows10-64-shippable-qr opt e10s stylo 139.00 -> 87.83
36% damp simple.netmonitor.requestsFinished.DAMP linux64-shippable-qr opt e10s stylo 146.37 -> 93.58
36% damp simple.netmonitor.requestsFinished.DAMP linux64-shippable opt e10s stylo 146.55 -> 93.91
19% damp complicated.netmonitor.close.DAMP windows10-64-shippable opt e10s stylo 44.47 -> 36.08
7% damp complicated.netmonitor.requestsFinished.DAMP linux64-shippable-qr opt e10s stylo 2,077.02 -> 1,932.99

For up to date results, see: https://treeherder.mozilla.org/perf.html#/alerts?id=24959