1711740 - Consider interrupting JS to unload displaylists / layers

Status: RESOLVED FIXED

(Core :: DOM: Content Processes, enhancement, P3)

Description

[Mike Conley (:mconley) (:⚙️)]

In BrowserChild, we check to see if the parent process has asked the BrowserChild to render layers - and if so, we interrupt JS if it's running to do the paint and upload to the compositor.

We don't, however, do any kind of JS interruption if the parent process has asked the BrowserChild to not render, and to unload layers.

In bug 1711381, Gijs ran into this issue when writing a test that intentionally runs a while(true) {} loop in a content process. We determined that when switching away from a tab in the hung content process, the AsyncTabSwitcher never fired the TabSwitchDone event, because the tab never reached the unloaded state. This is because the compositor was never told to unload its displaylist/layers for the tab, because the associated tab was hung.

We might want to consider interrupting JS to do unloads as well.

Comment 1

[Artur Iunusov]

Something similar to this:
https://searchfox.org/mozilla-central/rev/d62c4c4d5547064487006a1506287da394b64724/dom/ipc/ProcessHangMonitor.cpp#347,369-380

Comment 2

[Artur Iunusov]

Attachment: Bug 1711740 - Consider interrupting JS to unload layers, r=smaug

Comment 3

[Artur Iunusov]

It seems that unload now works correctly:
https://share.firefox.dev/3Rmwy6O

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/23f20a705af7
Consider interrupting JS to unload layers, r=smaug

Comment 5

[Sandor Molnar[:smolnar]]

https://hg.mozilla.org/mozilla-central/rev/23f20a705af7