1643514 - VR process is not shutdown after exiting WebVR pages

Status: RESOLVED FIXED

(Core :: WebVR, defect, P1)

Description

[Daosheng Mu[:daoshengmu]]

STR:

1. Open a tab and navigate to https://webvr.info/samples/04-simple-mirroring.html
2. Close this tab. Open another tab, go to https://www.wikipedia.org/.
3. Check if vr process is still alive after 5 seconds in Process Explorer.

However, if navigate to a WebXR page like https://immersive-web.github.io/webxr-samples/immersive-vr-session.html, and follow the step 2 - 3. We will see VR process is shutdown properly.

VR process takes 12% CPU on my laptop, so I think we should make sure its lifetime be managed correctly.

Comment 1

[Daosheng Mu[:daoshengmu]]

Attachment: Bug 1643514 - Clean up VRManager usage.

Comment 2

[Daosheng Mu[:daoshengmu]]

Attachment: Bug 1643514 - Avoid requesting VR display when it already completed.

Depends on D78436

Comment 3

[Daosheng Mu[:daoshengmu]]

It causes by [1]. Navigator::OnXRPermissionRequestAllow will be called a couple of times when entering a WebXR/WebVR page, then if the permission is granted, it will ask VRManager::EnumerateDevices. Once it starts to enumeration, mEnumerationRequested [2] will be false.

However, Due to [1], !usingWebXR makes VRManager continuously ask for enumeration, and mEnumerationRequested will be true then. Therefore, when we ask for shutdown VR process, it will be returned before Shutdown() [3].

It seems to be a regression and affect Gecko from FF 77, I will use moz-regression to check and give a uplift.

[1] https://searchfox.org/mozilla-central/rev/598e50d2c3cd81cd616654f16af811adceb08f9f/dom/base/Navigator.cpp#1570
[2] https://searchfox.org/mozilla-central/rev/598e50d2c3cd81cd616654f16af811adceb08f9f/gfx/vr/VRManager.cpp#695
[3] https://searchfox.org/mozilla-central/rev/7cadba1d8b8feaec4615f5bb98aac4b8a719793c/gfx/vr/VRManager.cpp#488

Comment 4

[Daosheng Mu[:daoshengmu]]

I have confirmed FF 77 - 79 are affected, we need to uplift it then.

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/0cea8390afe9
Clean up VRManager usage. r=kip,jrmuizel
https://hg.mozilla.org/integration/autoland/rev/5f7fbd09153c
Avoid requesting VR display when it already completed. r=kip,imanol

Comment 6

[Bogdan Tara[:bogdan_tara | bogdant]]

https://hg.mozilla.org/mozilla-central/rev/0cea8390afe9
https://hg.mozilla.org/mozilla-central/rev/5f7fbd09153c

Comment 7

[Daosheng Mu[:daoshengmu]]

Comment on attachment 9154435 [details]
Bug 1643514 - Avoid requesting VR display when it already completed.

Beta/Release Uplift Approval Request

• User impact if declined: VR process will continue to take very high percent CPU usage even though there is no WebVR pages exist in Firefox. Obviously, that VR process should be shutdown.
• Is this code covered by automated tests?: No
• Has the fix been verified in Nightly?: Yes
• Needs manual test from QE?: No
• If yes, steps to reproduce:
• List of other uplifts needed: None
• Risk to taking this patch: Low
• Why is the change risky/not risky? (and alternatives if risky): It only adds a flag in order to avoid our logic to block us shutdown VR process. We did that for WebXR already, we just need to follow the same way for WebVR.
• String changes made/needed:

Comment 8

[Julien Cristau [:jcristau] (back April 22)]

Do we need both patches on beta or just the second one?

Comment 9

[Daosheng Mu[:daoshengmu]]

(In reply to Julien Cristau [:jcristau] from comment #8)

Do we need both patches on beta or just the second one?

I think the second one is enough. You can do both if it is more convenient for you because the first one just has some code refinement.

Comment 10

[Julien Cristau [:jcristau] (back April 22)]

Comment on attachment 9154435 [details]
Bug 1643514 - Avoid requesting VR display when it already completed.

thanks for the clarification; approved for 78.0b7.

Comment 11

[Julien Cristau [:jcristau] (back April 22)]

https://hg.mozilla.org/releases/mozilla-beta/rev/c062691853ba