1268033 - Firefox becomes unresponsive when updating to 4.0.0b4

Status: VERIFIED FIXED

(Firefox for iOS :: General, defect)

Description

[Simon Basca [:SimonB]]

Build: 4.0.0b4

Steps to reproduce;
1. Start a browsing session in Firefox 4.0.0b3   
2. Background Firefox
3. Update to Firefox 4.0.0b4 via Testfilght

Actual results:
- Firefox becomes unresponsive and no browsing session can be started( no page is loaded)

Note:
- This issue dose not occur with a clean install

Comment 1

[Hanno Schlichting]

Same here, running on an iPad, iOS 9.3.2 (beta), upgraded from 4.0.0b3.

I can try to open one or two tabs, without any of them loading and than the entire app becomes unresponsive.

Comment 2

[Stephan Leroux [:sleroux]]

I was able to reproduce with a resigned version of the TestFlight build. Happened on the third time I upgraded from b3->b4. Nothing in the logs shows anything concerning though. The behavior I'm seeing is the web session fails to load the page, the toolbar items become unresponsive, and upon opening new tabs, the app eventually becomes full unresponsive.

Comment 3

[Stephan Leroux [:sleroux]]

Change list between b3 and b4: https://github.com/mozilla/firefox-ios/compare/a5ee3a8aef0793c23f78d856c0eb554cae169457...v4.x

Comment 5

[Hanno Schlichting]

build 5 fixes this for me.

Comment 6

[Simon Basca [:SimonB]]

Tested on build 4.0.0b5

The issue no longer occurs when updating from 4.0.0b3 to 4.0.0b5.

Comment 7

[Stephan Leroux [:sleroux]]

Good to hear. Should be fixed from the uplift on https://github.com/mozilla/firefox-ios/commit/3ebe958d25a6f467cfd980f39dd24e2e16fc4c9d. Marking as resolved.

Comment 8

[Dietrich Ayala (:dietrich)]

What bug fix was the cause of the regression?

Comment 9

[Stephan Leroux [:sleroux]]

As part of the core telemetry work we uplifted to the 4.0 branch, we set values on the profile from a background thread on app launch:

App Launch: https://github.com/mozilla/firefox-ios/commit/f719ed1df1c4de2a2c412ffa5e5cef10574150a3#diff-19fd1a6fe4b2f78eb457726f366733e0R152

Profile modification: https://github.com/mozilla/firefox-ios/commit/f719ed1df1c4de2a2c412ffa5e5cef10574150a3#diff-682af20e99900ae1d9196b24f2f17db9R25

This normally is fine but what was happening is upon setting a value to the profile, a notification is broadcasted across the app. In this case, our TabManager was listening to this nofication: https://github.com/mozilla/firefox-ios/commit/3ebe958d25a6f467cfd980f39dd24e2e16fc4c9d. The problem is that this notification is handled on a background thread and we access the web view from it which breaks things since the web view/UIKit is not thread safe.