1364554 - ANR on startup if session parsing takes longer than usual

Status: RESOLVED INCOMPLETE

(Firefox for Android Graveyard :: Session Restore, defect, P5)

Description

[Jan Henning [:JanH]]

Attachment: ANR report

STR:
Stick a Thread.sleep() at the start of this runnable (https://dxr.mozilla.org/mozilla-central/rev/8a7d0b15595f9916123848ca906f29c62d4914c9/mobile/android/base/java/org/mozilla/gecko/GeckoApp.java#1454) - on my phone, 3 s is already enough to trigger this bug.

Doing so means that the main thread will block here (https://dxr.mozilla.org/mozilla-central/rev/8a7d0b15595f9916123848ca906f29c62d4914c9/mobile/android/base/java/org/mozilla/gecko/GeckoApp.java#1798) during initialize() until "session restoring" (or rather sleeping in this case) has finished. This in itself is not a problem - with shorter sleep delays, we still end up waiting here for a few 100 ms, but manage to show the UI normally once execution resumes.

I'm not sure how realistic that kind of delay actually is in the wild, although bug 1279273 has shown that with big enough session files, parsing can take long enough for initialize() to at least momentarily enter the wait in initialize().

Result:
We just display a white screen and deadlock. Eventually, Android's ANR dialogue pops up.

Sending Firefox into the background immediately after starting Firefox and then waiting until the sleep() and session parsing have finished also seems to sidestep the issue.

Comment 1

[Firefox Bug Husbandry Bot]

Re-triaging per https://bugzilla.mozilla.org/show_bug.cgi?id=1473195

Needinfo :susheel if you think this bug should be re-triaged.

Comment 2

[BMO Automation]

We have completed our launch of our new Firefox on Android. The development of the new versions use GitHub for issue tracking. If the bug report still reproduces in a current version of [Firefox on Android nightly](https://play.google.com/store/apps/details?id=org.mozilla.fenix) an issue can be reported at the [Fenix GitHub project](https://github.com/mozilla-mobile/fenix/). If you want to discuss your report please use [Mozilla's chat](https://wiki.mozilla.org/Matrix#Connect_to_Matrix) server https://chat.mozilla.org and join the [#fenix](https://chat.mozilla.org/#/room/#fenix:mozilla.org) channel.