Filed by: cbrindusan [at] mozilla.com
Parsed log: https://treeherder.mozilla.org/logviewer.html#?job_id=259160888&repo=autoland
Full log: https://queue.taskcluster.net/v1/task/A5aFXDOhRJyhpndmzGw5ag/runs/0/artifacts/public/logs/live_backing.log

[task 2019-07-31T11:20:09.426Z] 11:20:09 INFO - TEST-START | dom/media/tests/mochitest/test_fingerprinting_resistance.html
[task 2019-07-31T11:20:09.446Z] 11:20:09 INFO - GECKO(1333) | ++DOMWINDOW == 7 (0x7fc5f42fec00) [pid = 1396] [serial = 7] [outer = 0x7fc5f49bc880]
[task 2019-07-31T11:20:09.732Z] 11:20:09 INFO - GECKO(1333) | ++DOMWINDOW == 3 (0x7fd61a6e6c00) [pid = 1508] [serial = 3] [outer = 0x7fd619b3ad40]
[task 2019-07-31T11:20:09.789Z] 11:20:09 INFO - GECKO(1333) | [Child 1508, Main Thread] WARNING: NS_ENSURE_SUCCESS(mStatus, *this) failed with result 0x80004005: file /builds/worker/workspace/build/src/obj-firefox/dist/include/nsIURIMutator.h, line 489
[task 2019-07-31T11:20:10.351Z] 11:20:10 INFO - GECKO(1333) | [Child 1508, Main Thread] WARNING: No active window: file /builds/worker/workspace/build/src/js/xpconnect/src/XPCJSContext.cpp, line 664
[task 2019-07-31T11:20:11.217Z] 11:20:11 INFO - GECKO(1333) | [Parent 1333, URL Classifier] WARNING: NS_ENSURE_SUCCESS(rv, rv) failed with result 0x80004005: file /builds/worker/workspace/build/src/toolkit/components/url-classifier/LookupCache.cpp, line 882
[task 2019-07-31T11:20:11.242Z] 11:20:11 INFO - [1045, Main Thread] WARNING: No active window: file /builds/worker/workspace/build/src/js/xpconnect/src/XPCJSContext.cpp, line 664
[task 2019-07-31T11:20:11.290Z] 11:20:11 INFO - GECKO(1333) | ++DOMWINDOW == 8 (0x7fc5f42fa000) [pid = 1396] [serial = 8] [outer = 0x7fc5f49bc880]
[task 2019-07-31T11:20:11.754Z] 11:20:11 INFO - GECKO(1333) | [Parent 1333, Main Thread] WARNING: Cannot set transparency mode on non-popup windows.: file /builds/worker/workspace/build/src/widget/gtk/nsWindow.cpp, line 4395
[task 2019-07-31T11:20:11.815Z] 11:20:11 INFO - GECKO(1333) | TEST DEVICES: Got loopback audio: Monitor of Null Output
[task 2019-07-31T11:20:11.816Z] 11:20:11 INFO - GECKO(1333) | TEST DEVICES: Got loopback video: Dummy video device (0x0000)
[task 2019-07-31T11:20:12.167Z] 11:20:12 INFO - GECKO(1333) | --DOMWINDOW == 7 (0x7fc5f3987000) [pid = 1396] [serial = 2] [outer = (nil)] [url = about:blank]
[task 2019-07-31T11:20:12.170Z] 11:20:12 INFO - GECKO(1333) | --DOMWINDOW == 6 (0x7fc5f396b400) [pid = 1396] [serial = 3] [outer = (nil)] [url = about:blank]
[task 2019-07-31T11:20:12.171Z] 11:20:12 INFO - GECKO(1333) | --DOMWINDOW == 5 (0x7fc5f3967000) [pid = 1396] [serial = 6] [outer = (nil)] [url = about:blank]
[task 2019-07-31T11:20:12.304Z] 11:20:12 INFO - GECKO(1333) | --DOMWINDOW == 4 (0x7fc5f42fec00) [pid = 1396] [serial = 7] [outer = (nil)] [url = about:blank]
[task 2019-07-31T11:20:12.403Z] 11:20:12 INFO - GECKO(1333) | WARN 2019-07-31T11:20:12Z: audio_thread_priority::rt_linux: Could not make thread real-time.
[task 2019-07-31T11:20:12.405Z] 11:20:12 INFO - GECKO(1333) | WARN 2019-07-31T11:20:12Z: audioipc_client::context: Could not promote thread to real-time.
[task 2019-07-31T11:20:12.440Z] 11:20:12 INFO - GECKO(1333) | [Child 1396, AudioIPC0] WARNING: No audio tracks, but full-duplex audio is enabled!!!!!: file /builds/worker/workspace/build/src/dom/media/MediaStreamGraph.cpp, line 336
[task 2019-07-31T11:20:12.460Z] 11:20:12 INFO - GECKO(1333) | ++DOCSHELL 0x7f10ca50f800 == 6 [pid = 1333] [id = {64c1c327-9d65-4cd4-b12e-6c85a788ee2f}]
[task 2019-07-31T11:20:12.462Z] 11:20:12 INFO - GECKO(1333) | ++DOMWINDOW == 14 (0x7f10c64fba60) [pid = 1333] [serial = 14] [outer = (nil)]
[task 2019-07-31T11:20:12.462Z] 11:20:12 INFO - GECKO(1333) | ++DOMWINDOW == 15 (0x7f10ca158c00) [pid = 1333] [serial = 15] [outer = 0x7f10c64fba60]
[task 2019-07-31T11:20:12.543Z] 11:20:12 INFO - GECKO(1333) | ++DOCSHELL 0x7f10c9427000 == 7 [pid = 1333] [id = {78962fe8-580a-4a94-8b0d-68335d829d43}]
[task 2019-07-31T11:20:12.545Z] 11:20:12 INFO - GECKO(1333) | ++DOMWINDOW == 16 (0x7f10c64fbc40) [pid = 1333] [serial = 16] [outer = (nil)]
[task 2019-07-31T11:20:12.548Z] 11:20:12 INFO - GECKO(1333) | ++DOMWINDOW == 17 (0x7f10ca15b800) [pid = 1333] [serial = 17] [outer = 0x7f10c64fbc40]
[task 2019-07-31T11:20:12.613Z] 11:20:12 INFO - GECKO(1333) | ++DOCSHELL 0x7f10caf10000 == 8 [pid = 1333] [id = {be9259a9-6854-4d7b-85b6-2fd9e364cacb}]
[task 2019-07-31T11:20:12.615Z] 11:20:12 INFO - GECKO(1333) | ++DOMWINDOW == 18 (0x7f10c64fbe20) [pid = 1333] [serial = 18] [outer = (nil)]
[task 2019-07-31T11:20:12.616Z] 11:20:12 INFO - GECKO(1333) | ++DOMWINDOW == 19 (0x7f10ca15c800) [pid = 1333] [serial = 19] [outer = 0x7f10c64fbe20]
[task 2019-07-31T11:20:12.682Z] 11:20:12 INFO - GECKO(1333) | ++DOCSHELL 0x7f10cad66800 == 9 [pid = 1333] [id = {112a1cf2-dbf6-47b7-a2d8-b86c7c28d859}]
[task 2019-07-31T11:20:12.683Z] 11:20:12 INFO - GECKO(1333) | ++DOMWINDOW == 20 (0x7f10ca0f9020) [pid = 1333] [serial = 20] [outer = (nil)]
[task 2019-07-31T11:20:12.683Z] 11:20:12 INFO - GECKO(1333) | ++DOMWINDOW == 21 (0x7f10ca166800) [pid = 1333] [serial = 21] [outer = 0x7f10ca0f9020]
[task 2019-07-31T11:20:12.744Z] 11:20:12 INFO - GECKO(1333) | ++DOCSHELL 0x7f10caf07800 == 10 [pid = 1333] [id = {dc484a94-9485-47b0-91da-c40c2e2ba8c3}]
[task 2019-07-31T11:20:12.746Z] 11:20:12 INFO - GECKO(1333) | ++DOMWINDOW == 22 (0x7f10ca0f9200) [pid = 1333] [serial = 22] [outer = (nil)]
[task 2019-07-31T11:20:12.747Z] 11:20:12 INFO - GECKO(1333) | ++DOMWINDOW == 23 (0x7f10ca3acc00) [pid = 1333] [serial = 23] [outer = 0x7f10ca0f9200]
[task 2019-07-31T11:20:12.765Z] 11:20:12 INFO - GECKO(1333) | Assertion failure: mInputDeviceID || CurrentDriver()->Switching(), at /builds/worker/workspace/build/src/dom/media/MediaStreamGraph.cpp:901

https://hg.mozilla.org/integration/autoland/annotate/cab1435d2f337308dd7a021a141d8995b2a34446/dom/media/MediaStreamGraph.cpp#l901

All the recent failures of this seem misclassified. The latest real one is on Aug 24th -- over a week ago.

I don't see anything relevant going in at that time really, nor do I recognize any of the recent patches as something that would have fixed this. Could be a latent issue that we end up exposing/hiding through timing changes?

https://wiki.mozilla.org/Bug_Triage#Intermittent_Test_Failure_Cleanup
For more information, please visit auto_nag documentation.