1594227 - Add menu item to open non-Fission window when Fission is enabled (and vice versa?)

Status: VERIFIED FIXED

(Firefox :: Menus, task)

Description

Fission is enabled on a per-window basis using the useRemoteSubframes flag on a docshell. It would be beneficial for dogfooding purposes to have "New non-Fission Window" and "Open in non-Fission Window" menu options for comparing behaviour with Fission enabled and disabled.

Comment 1

[Neha Kochar [:neha]]

Neil, could you look into enabling this?

Comment 2

[Mike Conley (:mconley) (:⚙️)]

Neil responded in the affirmative by email.

Comment 3

[Mike Conley (:mconley) (:⚙️)]

Attachment: Bug 1594227 - Add Fission testing menu items to the File menu. r?NeilDeakin

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/19d982541593
Add Fission testing menu items to the File menu. r=NeilDeakin

Comment 5

[Chris Peterson [:cpeterson]]

Will session restore remember the Fission-ness of restored windows?

Having Fission and non-Fission windows in the same browsing session will complicate A/B comparisons of Fission vs non-Fission. At this time, though, we don't think this will be a problem because we expect few users to open both Fission and non-Fission windows. To confirm this assumption, Corey Dow-Hygelund will file a bug to add a new telemetry probe counting how many Fission and non-Fission windows are opened.

Comment 6

[Mike Conley (:mconley) (:⚙️)]

Currently, no, this information is not persisted in SessionStore.

As I recall, we didn't persist that state when we worked on Electrolysis either - it was a process global setting as to whether or not we'd default to e10s windows, regardless of what the previous session was like.

Comment 7

[Kris Maglione [:kmag]]

(In reply to Mike Conley (:mconley) (:⚙️) (Wayyyy behind on needinfos) from comment #6)

Currently, no, this information is not persisted in SessionStore.

We should probably fix that, then. At least for windows explicitly opened in one mode or other. I'm currently assuming that people will mostly open non-Fission windows for sites that are broken in Fission, and if so restoring those tabs in Fission mode could lead to any number of issues, including data loss.

But even without that, it means that people won't be able to restart their browsers without losing their split between Fission and non-Fission windows (and probably won't be aware of it). Given that Fission testing will be happening exclusively on nightly, we want people to upgrade (and therefore restart their browsers) fairly often, and this may get in the way of that...

(In reply to Chris Peterson [:cpeterson] from comment #5)

At this time, though, we don't think this will be a problem because we expect few users to open both Fission and non-Fission windows.

I'm not sure that's true. But regardless, A/B testing should be done based on the Fission flags of a given window, not the state of the autostart pref.

Comment 8

[Cosmin Sabou [:CosminS]]

https://hg.mozilla.org/mozilla-central/rev/19d982541593

Comment 9

[Alexandru Trif, Desktop QA [:atrif]]

Verified with Firefox 72.0a1 (20191128214853) and Firefox 76.0a1 (20200329214909) on Windows 10x64, macOS 10.12 and Ubuntu 18.04. When in a fission session the menu item is Open Non-Fission Window and when in a non-fission session the menu is New Fission Window.