1797469 - [wayland] Maximizing/restoring window has become delayed with large numbers of tabs

Status: VERIFIED FIXED

(Firefox :: Tabbed Browser, defect)

Description

[Kestrel]

Attachment: Video showing maximize/restore delay with 2000 tabs on Wayland

STR:

1. Start with MOZ_ENABLE_WAYLAND=1 on Ubuntu 22.04.
2. Restore a window session with 2000 tabs.
3. Maximize the window.

Expected:

The window maximizes immediately.

Actual:

The window maximizes after a delay, the length of the delay increases with the number of tabs. It does not happen with the native system titlebar enabled (browser.tabs.inTitlebar = 0) or with XWayland.

Performance profile:
https://share.firefox.dev/3zgABcV

Regression window:
https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=894ad5982bff38a17909b61323273417a4662650&tochange=47e9c3d582b3a791cdf7914588ff15965cc8506e

Regressed by Bug 1795804.

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

:emilio, since you are the author of the regressor, bug 1795804, could you take a look? Also, could you set the severity field?

For more information, please visit auto_nag documentation.

Comment 2

[Emilio Cobos Álvarez (:emilio)]

Attachment: Bug 1797469 - Use a more specific selector for rounded corners of backdrops. r=dao,stransky

Only dialog elements can have backdrops. The current selector right now
acts like a global selector which causes a massive restyle when
maximizing / restoring the window.

Comment 3

[Emilio Cobos Álvarez (:emilio)]

Attachment: Bug 1797469 - Optimize better appearance changes. r=#layout

Some appearance changes like from -moz-window-titlebar to
-moz-window-titlebar-maximized shouldn't really cause layout of the
whole browser area.

Depends on D160354

Comment 4

[Emilio Cobos Álvarez (:emilio)]

Well, that's kind of expected I suspect. We now draw with the updated styles, all that work was happening after maximizing... But most of that work seems it could be faster.

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/edb9bc20edad
Use a more specific selector for rounded corners of backdrops. r=stransky

Comment 6

[Sandor Molnar[:smolnar]]

https://hg.mozilla.org/mozilla-central/rev/edb9bc20edad

Comment 7

[Catalin Sasca, Desktop Test Engineering [:csasca]]

Reproduced the issue on Firefox 108.0a1 (2022-10-26) on Ubuntu 22.04 Wayland by following the STR from Comment 0.

The issue is fixed on Firefox 108.0a1 (2022-11-01) and 109.0a1 (2022-11-23) on the same system and the Maximize action is much faster.