1490752 - Ensure that WebRender display lists aren't kept alive for all background tabs

Status: RESOLVED INVALID

(Core :: Graphics: WebRender, enhancement, P2)

Description

[Nicolas Silva [:nical]]

Background layer trees are kept alive for 300ms. I'm not 100% sure whether we do that with WebRender display lists or whether they just stay alive until the tab is closed.
We should investigate and make sure the behavior is similar to layers.

Comment 1

[Sotaro Ikeda [:sotaro]]

Tab resources are freed as same way as ClientLayerManager by calling ClearCachedResources() like the following.

TabChild::MakeHidden()
->TabChild::ClearCachedResources()
->WebRenderLayerManager::ClearCachedResources()
->WebRenderBridgeParent::RecvClearCachedResources()

Comment 2

[Bobby Holley (:bholley)]

Thanks Sotaro!

Looks like that will cause us to invoke ClearDisplayList here:

https://searchfox.org/mozilla-central/rev/819cd31a93fd50b7167979607371878c4d6f18e8/gfx/layers/wr/WebRenderBridgeParent.cpp#1306

Which I presume will drop the old display list and scene from WR.

So perhaps there's nothing left to do here. Nical, do you agree?

Comment 3

[Nicolas Silva [:nical]]

Agreed.