Bugzilla

### Beta/Release Uplift Approval Request
* **User impact if declined**: Unresponsive Firefox process on M1 Macs after fast user switching and system sleep
* **Is this code covered by automated tests?**: Yes
* **Has the fix been verified in Nightly?**: No
* **Needs manual test from QE?**: Yes
* **If yes, steps to reproduce**: Scenario A: Fast user switching (reproducible on all M1 Macs, and before bug 1422855, also on Intel Macs):
 1. Make sure you have two user accounts configured in macOS, and both accounts have "Fast user switching" enabled.
 2. On one account, open Firefox, load attachment 9206004 [details], and keep it open in a foreground tab.
 3. Using the system status bar fast user switching menu in the top right corner of the screen, switch to the other account.
 4. Switch back to the original account the same way.
At this point, Firefox would be frozen.
Bug 1422855 fixed this bug for Intel Macs and this bug fixed it for M1 Macs.

Scenario B: After system sleep (reproducible on M1 Mac Mini, and for some users on M1 Macbook Pro with an external screen):
 1. Open Firefox, load attachment 9206004 [details], and keep it open in a foreground tab.
 2. Send the machine to sleep using [Apple menu] -> Sleep.
 3. Wait until the machine has become fully silent. Wait 20 more seconds. If the machine makes any noise whatsoever, wait until it's fully silent again and wait 20 more seconds.
 4. Wake the machine from sleep.
At this point, Firefox would be frozen, before this bug's fix.
* **List of other uplifts needed**: 1422855 (already present on 87, but would need to be uplifted to 86)
* **Risk to taking this patch**: Low
* **Why is the change risky/not risky? (and alternatives if risky)**: Very tightly-scoped fix.
* **String changes made/needed**: none

### Beta/Release Uplift Approval Request
* **User impact if declined**: Unresponsive Firefox process on M1 Macs after fast user switching and system sleep
* **Is this code covered by automated tests?**: Yes
* **Has the fix been verified in Nightly?**: No
* **Needs manual test from QE?**: Yes
* **If yes, steps to reproduce**: Scenario A: Fast user switching (reproducible on all M1 Macs, and before bug 1422855, also on Intel Macs):
 1. Make sure you have two user accounts configured in macOS, and both accounts have "Fast user switching" enabled.
 2. On one account, open Firefox, load attachment 9206004 [details], and keep it open in a foreground tab.
 3. Using the system status bar fast user switching menu in the top right corner of the screen, switch to the other account.
 4. Switch back to the original account the same way.
At this point, Firefox would be frozen.
Bug 1422855 fixed this bug for Intel Macs and this bug fixed it for M1 Macs.

Scenario B: After system sleep (reproducible on M1 Mac Mini, and for some users on M1 Macbook Pro with an external screen):
 1. Open Firefox, load attachment 9206004 [details], and keep it open in a foreground tab.
 2. Send the machine to sleep using [Apple menu] -> Sleep.
 3. Wait until the machine has become fully silent. Wait 20 more seconds. If the machine makes any noise whatsoever, wait until it's fully silent again and wait 20 more seconds.
 4. Wake the machine from sleep.
At this point, Firefox would be frozen, before this bug's fix.
* **List of other uplifts needed**: bug 1422855 (already present on 87, but would need to be uplifted to 86)
* **Risk to taking this patch**: Low
* **Why is the change risky/not risky? (and alternatives if risky)**: Very tightly-scoped fix.
* **String changes made/needed**: none

### Beta/Release Uplift Approval Request
* **User impact if declined**: Unresponsive Firefox process on M1 Macs after fast user switching and system sleep
* **Is this code covered by automated tests?**: Yes
* **Has the fix been verified in Nightly?**: No
* **Needs manual test from QE?**: Yes
* **If yes, steps to reproduce**: Scenario A: Fast user switching (reproducible on all M1 Macs, and before bug 1422855, also on Intel Macs):
 1. Make sure you have two user accounts configured in macOS, and both accounts have "Fast user switching" enabled.
 2. On one account, open Firefox, load attachment 9206004 [details], and keep it open in a foreground tab.
 3. Using the system status bar fast user switching menu in the top right corner of the screen, switch to the other account.
 4. Switch back to the original account the same way.

At this point, Firefox would be frozen.
Bug 1422855 fixed this bug for Intel Macs and this bug fixed it for M1 Macs.

Scenario B: After system sleep (reproducible on M1 Mac Mini, and for some users on M1 Macbook Pro with an external screen):
 1. Open Firefox, load attachment 9206004 [details], and keep it open in a foreground tab.
 2. Send the machine to sleep using [Apple menu] -> Sleep.
 3. Wait until the machine has become fully silent. Wait 20 more seconds. If the machine makes any noise whatsoever, wait until it's fully silent again and wait 20 more seconds.
 4. Wake the machine from sleep.

At this point, Firefox would be frozen, before this bug's fix.
* **List of other uplifts needed**: bug 1422855 (already present on 87, but would need to be uplifted to 86)
* **Risk to taking this patch**: Low
* **Why is the change risky/not risky? (and alternatives if risky)**: Very tightly-scoped fix.
* **String changes made/needed**: none