1598356 - Very long main-thread hangs when visiting YouTube in Nightly launched from DMG image - blocked launching the RDD process

Status: NEW

(Core :: Audio/Video: Playback, defect, P3)

Description

[Mike Conley (:mconley) (:⚙️)]

STR:

1. Download German locale version of Nightly from https://www.mozilla.org/en-US/firefox/all/#product-desktop-nightly, but do not install it
2. Launch the German instance of Nightly with the new profile by running it from the .dmg Disk Image
3. Visit https://www.youtube.com
4. Try to watch any video.

ER:

The video should play smoothly.

AR:

Long, multi-second main-thread hangs. The video eventually fails to play and displays an error message (I'll attach a screenshot with the error message).

Comment 1

[Mike Conley (:mconley) (:⚙️)]

Attachment: Screenshot of error

Comment 2

[Mike Conley (:mconley) (:⚙️)]

Here's a profile: https://perfht.ml/2KI7m9M

Comment 3

[Mike Conley (:mconley) (:⚙️)]

We suspect this has to do with running the Nightly executable from the .dmg directly, rather than from the Applications folder or elsewhere on the disk proper. Updating the STR in comment 0 to reflect that.

Comment 4

[Jean-Yves Avenard [:jya]]

Can you reproduce this in a non-German version? surely it shouldn't matter.

Comment 5

[Markus Stange [:mstange]]

I can reproduce this on the English version as well, and on any of my try builds, as long as I launch them directly from the mounted DMG image.

My guess is something is crashing in the RDD process when trying to write to a read-only file system.

Comment 6

[Daniel Holbert [:dholbert]]

QF triage: this seems like a correctness issue more than a perf issue (in that the video just fails to play, though there are some hangs leading up to it). Also, hopefully this doesn't affect common usage, it's since running directly from inside a DMG probably isn't a common scenario (and isn't even possible beyond mac)

Hence, calling this p3 from a QF perspective; but definitely worth investigating/fixing from a correctness perspective.