1648405 - Use crossbeam_channel instead of std::mpsc in WebRender

Status: RESOLVED FIXED

(Core :: Graphics: WebRender, task, P3)

Description

[Nicolas Silva [:nical]]

The main motivation is to have access to crossbeam's select feature, in the hope that we can remove some hacks we do with some even loops that pull from multiple channels. As a bonus crossbeam is reportedly much faster than std::mpsc.

Comment 1

[Nicolas Silva [:nical]]

Attachment: Bug 1648405 - Use crossbeam channels instead of std::mpsc ones in webrender. r=gw

Comment 2

[Nicolas Silva [:nical]]

Attachment: Bug 1648405 - Vendor crossbeam dependency. r=gw

Depends on D81040

Comment 3

[Nicolas Silva [:nical]]

Attachment: Bug 1648405 - Remove the need for a ApiMsg::WakeUp. r=gw

Depends on D81041

Comment 4

[Nicolas Silva [:nical]]

Attachment: Bug 1648405 - Remove the need for SceneBuilderRequest::BackendMessage. r=gw

This introduces a slight behavior change in that the backend messages will go directly to the scene builder thread without going through the low-priority scene builder. In most cases this should not be an issue because it only contains debugging related messages originating from user inputs so respective ordering with specific transactions is already not possible to enforce/observe.

Comment 5

[Nicolas Silva [:nical]]

Attachment: Bug 1648405 - Remove the need for SceneBuilderRequest::BackendMessage. r=gw

This introduces a slight behavior change in that the backend messages will go directly to the scene builder thread without going through the low-priority scene builder. In most cases this should not be an issue because it only contains debugging related messages originating from user inputs so respective ordering with specific transactions is already not possible to enforce/observe.

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/c73ffc91ade2
Use crossbeam channels instead of std::mpsc ones in webrender. r=gw
https://hg.mozilla.org/integration/autoland/rev/50a2b61977d5
Vendor crossbeam dependency. r=gw

Comment 7

[Sebastian Hengst [:aryx] (needinfo me if it's about an intermittent or backout)]

https://hg.mozilla.org/mozilla-central/rev/c73ffc91ade2
https://hg.mozilla.org/mozilla-central/rev/50a2b61977d5

Comment 8

[Alexandru Ionescu (needinfo me) [:alexandrui]]

== Change summary for alert #26628 (as of Fri, 31 Jul 2020 02:32:27 GMT) ==

Improvements:

5% tscrollx linux64-shippable-qr opt e10s stylo 1.64 -> 1.56
4% tscrollx linux64-shippable-qr opt e10s stylo 1.63 -> 1.57

For up to date results, see: https://treeherder.mozilla.org/perf.html#/alerts?id=26628