Filed by: nerli [at] mozilla.com
Parsed log: https://treeherder.mozilla.org/logviewer.html#?job_id=285857028&repo=mozilla-beta
Full log: https://firefox-ci-tc.services.mozilla.com/api/queue/v1/task/GQkA_DR3RTCOTHONhU_TxQ/runs/0/artifacts/public/logs/live_backing.log

[task 2020-01-21T23:23:12.326Z] 23:23:12 INFO - TEST-START | browser/base/content/test/general/browser_bug767836_perwindowpb.js
[task 2020-01-21T23:23:13.114Z] 23:23:13 INFO - GECKO(1908) | JavaScript error: resource://gre/modules/XULStore.jsm, line 66: Error: Can't find profile directory.
[task 2020-01-21T23:23:13.231Z] 23:23:13 INFO - GECKO(1908) | JavaScript error: resource://gre/modules/XULStore.jsm, line 66: Error: Can't find profile directory.
[task 2020-01-21T23:23:13.476Z] 23:23:13 INFO - GECKO(1908) | JavaScript error: , line 0: uncaught exception: undefined
[task 2020-01-21T23:23:13.476Z] 23:23:13 INFO - TEST-INFO | started process screentopng
[task 2020-01-21T23:23:13.890Z] 23:23:13 INFO - TEST-INFO | screentopng: exit 0
[task 2020-01-21T23:23:13.890Z] 23:23:13 INFO - Buffered messages logged at 23:23:12
[task 2020-01-21T23:23:13.890Z] 23:23:13 INFO - Entering test bound test_newTabService
[task 2020-01-21T23:23:13.890Z] 23:23:13 INFO - TEST-PASS | browser/base/content/test/general/browser_bug767836_perwindowpb.js | No custom newtab url is set -
[task 2020-01-21T23:23:13.890Z] 23:23:13 INFO - TEST-PASS | browser/base/content/test/general/browser_bug767836_perwindowpb.js | URL of NewTab should be about:newtab in normal mode -
[task 2020-01-21T23:23:13.890Z] 23:23:13 INFO - TEST-PASS | browser/base/content/test/general/browser_bug767836_perwindowpb.js | Custom newtab url is set -
[task 2020-01-21T23:23:13.891Z] 23:23:13 INFO - TEST-PASS | browser/base/content/test/general/browser_bug767836_perwindowpb.js | URL of NewTab should be the custom url -
[task 2020-01-21T23:23:13.891Z] 23:23:13 INFO - TEST-PASS | browser/base/content/test/general/browser_bug767836_perwindowpb.js | No custom newtab url is set -
[task 2020-01-21T23:23:13.891Z] 23:23:13 INFO - Console message: [JavaScript Error: "[Exception... "Component returned failure code: 0x80004005 (NS_ERROR_FAILURE) [nsIControllers.removeController]" nsresult: "0x80004005 (NS_ERROR_FAILURE)" location: "JS frame :: chrome://global/content/elements/browser-custom-element.js :: destroy :: line 1374" data: no]"]
[task 2020-01-21T23:23:13.891Z] 23:23:13 INFO - destroy@chrome://global/content/elements/browser-custom-element.js:1374:28
[task 2020-01-21T23:23:13.892Z] 23:23:13 INFO - disconnectedCallback@chrome://global/content/elements/browser-custom-element.js:408:12
[task 2020-01-21T23:23:13.892Z] 23:23:13 INFO - removePreloadedBrowser@resource:///modules/NewTabPagePreloading.jsm:200:41
[task 2020-01-21T23:23:13.892Z] 23:23:13 INFO - onUnload@chrome://browser/content/browser.js:2448:26
[task 2020-01-21T23:23:13.892Z] 23:23:13 INFO -
[task 2020-01-21T23:23:13.898Z] 23:23:13 INFO - Buffered messages logged at 23:23:13
[task 2020-01-21T23:23:13.900Z] 23:23:13 INFO - Console message: [JavaScript Error: "Error: Can't find profile directory." {file: "resource://gre/modules/XULStore.jsm" line: 66}]
[task 2020-01-21T23:23:13.900Z] 23:23:13 INFO - Console message: [JavaScript Error: "Error: Can't find profile directory." {file: "resource://gre/modules/XULStore.jsm" line: 66}]
[task 2020-01-21T23:23:13.901Z] 23:23:13 INFO - TEST-PASS | browser/base/content/test/general/browser_bug767836_perwindowpb.js | URL of NewTab should be about:privatebrowsing in per window private browsing mode -
[task 2020-01-21T23:23:13.901Z] 23:23:13 INFO - TEST-PASS | browser/base/content/test/general/browser_bug767836_perwindowpb.js | Custom newtab url is set -
[task 2020-01-21T23:23:13.903Z] 23:23:13 INFO - TEST-PASS | browser/base/content/test/general/browser_bug767836_perwindowpb.js | URL of NewTab should be the custom url -
[task 2020-01-21T23:23:13.903Z] 23:23:13 INFO - TEST-PASS | browser/base/content/test/general/browser_bug767836_perwindowpb.js | No custom newtab url is set -
[task 2020-01-21T23:23:13.903Z] 23:23:13 INFO - Buffered messages finished
[task 2020-01-21T23:23:13.904Z] 23:23:13 INFO - TEST-UNEXPECTED-FAIL | browser/base/content/test/general/browser_bug767836_perwindowpb.js | A promise chain failed to handle a rejection: (Unable to convert rejection reason to string.) - stack: (No stack available.)
[task 2020-01-21T23:23:13.904Z] 23:23:13 INFO - Rejection date: Tue Jan 21 2020 23:23:13 GMT+0000 (Coordinated Universal Time) - false == true - JS frame :: resource://testing-common/PromiseTestUtils.jsm :: assertNoUncaughtRejections :: line 265
[task 2020-01-21T23:23:13.904Z] 23:23:13 INFO - Stack trace:
[task 2020-01-21T23:23:13.905Z] 23:23:13 INFO - resource://testing-common/PromiseTestUtils.jsm:assertNoUncaughtRejections:265
[task 2020-01-21T23:23:13.905Z] 23:23:13 INFO - chrome://mochikit/content/browser-test.js:Tester_execTest/<:1093
[task 2020-01-21T23:23:13.906Z] 23:23:13 INFO - Leaving test bound test_newTabService
[task 2020-01-21T23:23:13.906Z] 23:23:13 INFO - Console message: [JavaScript Error: "uncaught exception: undefined"]
[task 2020-01-21T23:23:13.906Z] 23:23:13 INFO - GECKO(1908) | MEMORY STAT | vsize 3346MB | residentFast 520MB | heapAllocated 266MB
[task 2020-01-21T23:23:13.907Z] 23:23:13 INFO - TEST-OK | browser/base/content/test/general/browser_bug767836_perwindowpb.js | took 1152ms
[task 2020-01-21T23:23:13.907Z] 23:23:13 INFO - checking window state
[task 2020-01-21T23:23:13.908Z] 23:23:13 INFO - GECKO(1908) | must wait for focus

Could this be a regression from 1607937?

No, that bug wouldn't have affected this. It's policy only and only related to addons.

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

This is still happening.

Recent failure: https://treeherder.mozilla.org/logviewer?job_id=322914268&repo=autoland&lineNumber=2280

Bugbug thinks this bug should belong to this component, but please revert this change in case of error.

It seems that the frequency has been increased: https://treeherder.mozilla.org/jobs?repo=autoland&resultStatus=pending%2Crunning%2Csuccess%2Ctestfailed%2Cbusted%2Crunnable&fromchange=3f6e90beb51e4ada67566132ae93f028e59dee38&searchStr=linux%2C18.04%2Cx64%2Cdebug%2Cmochitests%2Ctest-linux1804-64%2Fdebug-mochitest-browser-chrome-e10s%2Cbc4&selectedTaskRun=Jnsi7zcwTbWP7q_TGdmK7A.1

Retriggers: https://treeherder.mozilla.org/jobs?repo=autoland&test_paths=browser%2Fbase%2Fcontent%2Ftest%2Fgeneral%2F&tochange=08cd8d747c33ab8d092ea6de2aac565e79093b3e&fromchange=1c8480affdfd71eeced35da2b6acf3d8b36f0523&searchStr=Windows%2C10%2Cx64%2Casan&group_state=expanded

https://treeherder.mozilla.org/jobs?repo=autoland&searchStr=Windows%2C10%2Cx64%2Casan%2CMochitests%2Ctest-windows10-64-asan%2Fopt-mochitest-browser-chrome-e10s%2Cbc1&tochange=08cd8d747c33ab8d092ea6de2aac565e79093b3e&fromchange=1c8480affdfd71eeced35da2b6acf3d8b36f0523&group_state=expanded

Robert, could bug 1645528 have caused a failure increase here?

Yes, that can indeed be the case. However, there're reasons assume that the patch is not "at fault" :)

After bug 1645528 the order and exact timing of when certain events fire might have changed. All tests that are "flaky" in the sense that they rely on implicit, or rather invalid, assumptions about the timing may change for the better or worse - see for example bug 1602701, which now almost perma-fails on X11. In that case bug, however, it was already known that the test did not use the appropriate method to wait for things to happen.

Given that this issue is not new and the fact that until now the failure rate seems to be in the 10-15% range, I suppose there's a good chance that it is timing-sensitive as well. If there was something actionable about bug 1645528 I'd assume to see way more test starting to spike, as it affects all platforms in a quite central place.

So from my site I'd recommend having a closer look at the test itself, rather than bug 1645528.

Scott, could you redirect this to someone to take a look over this flaky test. It has:

• 162 total failures in the last 30 days: https://treeherder.mozilla.org/intermittent-failures/bugdetails?startday=2020-11-28&endday=2020-12-05&tree=trunk&bug=1610710

Recent failure log: https://treeherder.mozilla.org/logviewer?job_id=323664233&repo=autoland&lineNumber=2573
Meanwhile I've disabled this on linux and windows asan because of the high failure rate.
Thank you.

https://hg.mozilla.org/mozilla-central/rev/489c19245ebc

https://hg.mozilla.org/mozilla-central/rev/58cc9db51ef9

https://hg.mozilla.org/mozilla-central/rev/7e64b7127814

Can we re-enable the test on linux/win asan?

(In reply to :Gijs (he/him) from comment #26)

Can we re-enable the test on linux/win asan?

The test is enabled on all platforms: https://searchfox.org/mozilla-central/source/browser/base/content/test/general/browser.ini#177