Ok, so I finally was able to retrieve a Gecko profile from such a hang. It can be found here: https://share.firefox.dev/3Ajrisj Some comments in regards in how it has been created: 1. Further I modified the Marionette code to calculate the time for receiving the `browser-idle-startup-tasks-finished` notification within the new session command and if longer than 10s it would enter a not resolving promise. This gives me time to actually get the profile data. 2. I've run: `MOZ_PROFILER_STARTUP=1 ./mach marionette-test --binary=path/to/firefox -vv --gecko-log=- testing/marionette/harness/marionette_harness/tests/unit/test_quit_restart.py --run-until-failure` (this enables startup profiling as well) 3. When Firefox was in a broken state I was waiting nearly a minute before minimizing it via the task bar icon 4. Restoring the window finally caused the `browser-idle-startup-tasks-finished` notification to be sent. 5. Then I entered Toolbar customization to add the profiler button to the tool bar. 6. And finally I stopped the profiler and uploaded the profile. I hope that this finally contains helpful information why this hang is taking place randomly.
Bug 1784591 Comment 41 Edit History
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Ok, so I finally was able to retrieve a Gecko profile from such a hang. It can be found here: https://share.firefox.dev/3Ajrisj Some comments in regards in how it has been created: 1. I modified the Marionette code to calculate the time for receiving the `browser-idle-startup-tasks-finished` notification within the new session command and if longer than 10s it would enter a not resolving promise. This gives me time to actually get the profile data. 2. I've run: `MOZ_PROFILER_STARTUP=1 ./mach marionette-test --binary=path/to/firefox -vv --gecko-log=- testing/marionette/harness/marionette_harness/tests/unit/test_quit_restart.py --run-until-failure` (this enables startup profiling for the Firefox CCOV build) 3. When Firefox was in a broken state I was waiting nearly a minute before minimizing it via the task bar icon 4. Restoring the window finally caused the `browser-idle-startup-tasks-finished` notification to be sent. 5. Then I entered Toolbar customization to add the profiler button to the tool bar. 6. And finally I stopped the profiler and uploaded the profile. I hope that this finally contains helpful information why this hang is taking place randomly.