Filed by: imoraru [at] mozilla.com
Parsed log: https://treeherder.mozilla.org/logviewer?job_id=361211482&repo=mozilla-beta
Full log: https://firefox-ci-tc.services.mozilla.com/api/queue/v1/task/JBHVz_mcSK-pkdGh4yKrKQ/runs/0/artifacts/public/logs/live_backing.log

[task 2021-12-14T19:47:54.250Z] 19:47:54     INFO - TEST-START | dom/media/webrtc/tests/mochitests/test_getUserMedia_basicWindowshare.html
[task 2021-12-14T19:47:54.446Z] 19:47:54     INFO - GECKO(5877) | TEST DEVICES: Got loopback audio: Monitor of Null Output
[task 2021-12-14T19:47:54.449Z] 19:47:54     INFO - GECKO(5877) | TEST DEVICES: Got loopback video: Dummy video device (0x0000)
[task 2021-12-14T19:47:54.610Z] 19:47:54     INFO - GECKO(5877) | TEST DEVICES: Got loopback audio: Monitor of Null Output
[task 2021-12-14T19:47:54.613Z] 19:47:54     INFO - GECKO(5877) | TEST DEVICES: Got loopback video: Dummy video device (0x0000)
[task 2021-12-14T19:47:54.619Z] 19:47:54     INFO - GECKO(5877) | TEST DEVICES: Got loopback audio: Monitor of Null Output
[task 2021-12-14T19:47:54.621Z] 19:47:54     INFO - GECKO(5877) | TEST DEVICES: Got loopback video: Dummy video device (0x0000)
[task 2021-12-14T19:47:54.979Z] 19:47:54     INFO - GECKO(5877) | (firefox:5877): Gdk-ERROR **: 19:47:54.976: The program 'firefox' received an X Window System error.
[task 2021-12-14T19:47:54.980Z] 19:47:54     INFO - GECKO(5877) | This probably reflects a bug in the program.
[task 2021-12-14T19:47:54.981Z] 19:47:54     INFO - GECKO(5877) | The error was 'BadDrawable (invalid Pixmap or Window parameter)'.
[task 2021-12-14T19:47:54.981Z] 19:47:54     INFO - GECKO(5877) |   (Details: serial 11883 error_code 9 request_code 55 (core protocol) minor_code 0)
[task 2021-12-14T19:47:54.982Z] 19:47:54     INFO - GECKO(5877) |   (Note to programmers: normally, X errors are reported asynchronously;
[task 2021-12-14T19:47:54.982Z] 19:47:54     INFO - GECKO(5877) |    that is, you will receive the error a while after causing it.
[task 2021-12-14T19:47:54.982Z] 19:47:54     INFO - GECKO(5877) |    To debug your program, run it with the GDK_SYNCHRONIZE environment
[task 2021-12-14T19:47:54.982Z] 19:47:54     INFO - GECKO(5877) |    variable to change this behavior. You can then get a meaningful
[task 2021-12-14T19:47:54.982Z] 19:47:54     INFO - GECKO(5877) |    backtrace from your debugger if you break on the gdk_x_error() function.)
[task 2021-12-14T19:47:55.086Z] 19:47:55     INFO - GECKO(5877) | Exiting due to channel error.
[task 2021-12-14T19:47:55.086Z] 19:47:55     INFO - GECKO(5877) | Exiting due to channel error.
[task 2021-12-14T19:47:55.086Z] 19:47:55     INFO - GECKO(5877) | Exiting due to channel error.
[task 2021-12-14T19:47:55.086Z] 19:47:55     INFO - GECKO(5877) | Exiting due to channel error.
[task 2021-12-14T19:47:55.188Z] 19:47:55     INFO - TEST-INFO | Main app process: killed by SIGTRAP
[task 2021-12-14T19:47:55.189Z] 19:47:55     INFO - Buffered messages logged at 19:47:54
[task 2021-12-14T19:47:55.190Z] 19:47:55     INFO - TEST-PASS | dom/media/webrtc/tests/mochitests/test_getUserMedia_basicWindowshare.html | A valid string reason is expected 
<...>
[task 2021-12-14T19:47:55.206Z] 19:47:55     INFO - TEST-PASS | dom/media/webrtc/tests/mochitests/test_getUserMedia_basicWindowshare.html | Current src should still be an empty string 
[task 2021-12-14T19:47:55.207Z] 19:47:55     INFO - TEST-FAIL | dom/media/webrtc/tests/mochitests/test_getUserMedia_basicWindowshare.html | The author of the test has indicated that flaky timeouts are expected.  Reason: WebRTC inherently depends on timeouts 
[task 2021-12-14T19:47:55.208Z] 19:47:55     INFO - Buffered messages finished
[task 2021-12-14T19:47:55.208Z] 19:47:55    ERROR - TEST-UNEXPECTED-FAIL | dom/media/webrtc/tests/mochitests/test_getUserMedia_basicWindowshare.html | application terminated with exit code -5
[task 2021-12-14T19:47:55.209Z] 19:47:55     INFO - runtests.py | Application ran for: 0:01:53.349167

Darkspirit, do you if there is an open bug tracking these The error was 'BadDrawable (invalid Pixmap or Window parameter)'. failures.

No, but I had filed bug 1742708.
IIUC, lsalzman indicated that bug 1740800 would be related to bug 1741956.

If the CI is running hardware WebRender on the blocklisted "intel" DDX driver and not on "modesetting",
then it would be interesting if switching to the recommended "modesetting" driver would help (simply by removing the deprecated driver: sudo apt-get remove xserver-xorg-video-intel).

If it doesn't help, then the CI might be running into a general problem of older Ubuntu: bug 1743551
Then it might be neccessary to blocklist HW WR entirely for unpatched Ubuntu versions, so that GLX rendering thread and GLX vsync thread etc. don't interfere with each other, but "Incidence of crashes still seems low enough that maybe this is not that bad.".

IMHO: If it's not already the case: Better don't force-enable WR, but add a hidden gfx.webrender.crash-if-not-qualified-for-hw-wr pref, so that the CI itself is tested for compatibility.

https://wiki.mozilla.org/Bug_Triage#Intermittent_Test_Failure_Cleanup
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