1720966 - Force-enable LSNG when Fission is enabled

Status: RESOLVED WONTFIX

(Core :: Storage: localStorage & sessionStorage, task)

Description

[Chris Peterson [:cpeterson]]

LSNG fixes some Fission localStorage bugs, so we never want to use Fission without LSNG. We can force-enable LSNG when Fission is enabled.

IIUC, we can check whether Fission is enabled with FissionAutostart() in LSNG's initialization function MaybeEnableNextGenLocalStorage():

https://searchfox.org/mozilla-central/rev/c0fc8c4852e927b0ae75d893d35772b8c60ee06b/dom/localstorage/LocalStorageCommon.cpp#46

Comment 1

[Chris Peterson [:cpeterson]]

This bug is a hard blocker for Fission M8.

Comment 2

[Chris Peterson [:cpeterson]]

Edgar, do you have time to fix bug for our Fission M8 milestone? The patch just needs to force-enable LSNG (localStorage Next Generation) when Fission is enabled. Jan Varga (LSNG engineer) would be the appropriate code reviewer.

https://searchfox.org/mozilla-central/rev/c0fc8c4852e927b0ae75d893d35772b8c60ee06b/dom/localstorage/LocalStorageCommon.cpp#46

This bug is important because the legacy/current implementation of localStorage has some serious bugs when used with Fission. LSNG is enabled by default in Nightly and "early" Beta (the first two week so the Beta cycle), but not "late" Beta or Release. We see some Fission crashes (like bug 1722988) in late Beta.

Comment 3

[Chris Peterson [:cpeterson]]

In bug 1599979 comment 5, Jens says LSNG will ride the trains with Firefox 92. In that case, we don't need to force-enable LSNG for Fission users. I will resolve this bug as WONTFIX.