Filed by: rmaries [at] mozilla.com
Parsed log: https://treeherder.mozilla.org/logviewer.html#?job_id=306295631&repo=autoland
Full log: https://firefox-ci-tc.services.mozilla.com/api/queue/v1/task/XGXFzS9HR2KxhcKoH3RhfQ/runs/0/artifacts/public/logs/live_backing.log

[task 2020-06-14T15:26:15.183Z] 15:26:15 INFO - TEST-START | dom/credentialmanagement/tests/mochitest/test_credman_iframes.html
[task 2020-06-14T15:26:18.364Z] 15:26:18 INFO - GECKO(1612) | #39 do_main /builds/worker/checkouts/gecko/browser/app/nsBrowserApp.cpp:217:22 (firefox+0xca433)
[task 2020-06-14T15:26:18.364Z] 15:26:18 INFO - GECKO(1612) | #40 main /builds/worker/checkouts/gecko/browser/app/nsBrowserApp.cpp:331:16 (firefox+0xca433)
[task 2020-06-14T15:26:18.365Z] 15:26:18 INFO - GECKO(1612) | SUMMARY: ThreadSanitizer: data race /builds/worker/checkouts/gecko/netwerk/protocol/http/nsHttpHandler.cpp:1975:27 in mozilla::net::nsHttpHandler::PrefsChanged(char const*)
[task 2020-06-14T15:26:18.365Z] 15:26:18 INFO - GECKO(1612) | ==================
[task 2020-06-14T15:26:18.366Z] 15:26:18 INFO - GECKO(1612) | Crash Annotation GraphicsCriticalError: |[C0][GFX1-]: Receive IPC close with reason=AbnormalShutdown (t=11.3857) [GFX1-]: Receive IPC close with reason=AbnormalShutdown
[task 2020-06-14T15:26:18.367Z] 15:26:18 INFO - GECKO(1612) | Exiting due to channel error.
[task 2020-06-14T15:26:18.367Z] 15:26:18 INFO - GECKO(1612) | Crash Annotation GraphicsCriticalError: |[C0][GFX1-]: Receive IPC close with reason=AbnormalShutdown (t=14.1084) [GFX1-]: Receive IPC close with reason=AbnormalShutdown
[task 2020-06-14T15:26:18.367Z] 15:26:18 INFO - GECKO(1612) | Exiting due to channel error.
[task 2020-06-14T15:26:18.368Z] 15:26:18 INFO - GECKO(1612) | Crash Annotation GraphicsCriticalError: |[C0][GFX1-]: Receive IPC close with reason=AbnormalShutdown (t=25.7987) [GFX1-]: Receive IPC close with reason=AbnormalShutdown
[task 2020-06-14T15:26:18.368Z] 15:26:18 INFO - GECKO(1612) | Exiting due to channel error.
[task 2020-06-14T15:26:18.369Z] 15:26:18 INFO - GECKO(1612) | Exiting due to channel error.
[task 2020-06-14T15:26:19.378Z] 15:26:19 INFO - GECKO(1612) | Crash Annotation GraphicsCriticalError: |[C0][GFX1-]: Receive IPC close with reason=AbnormalShutdown (t=24.8695)
[task 2020-06-14T15:26:19.413Z] 15:26:19 INFO - TEST-INFO | Main app process: killed by SIGIOT

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

recent failure: https://treeherder.mozilla.org/logviewer.html#/jobs?job_id=311449432&repo=autoland&lineNumber=2947

This is specifically caused by the bool mResponseTimeoutEnabled, which we are reading on the socket thread during nsHTTPConnection::Activate. We're always going to call PrefsChanged on the main thread, so to avoid racing with the socket thread we probably ought to make mResponseTimeoutEnabled atomic or something. I haven't checked to see if anything else being read off that prefs list would have the same issue.

Gonna suppress this as I think Bug 1683730 makes it worse. That said, I think we should also send the naive fix to the netwerk team's desk and see what they think.

Depends on D100268

https://hg.mozilla.org/mozilla-central/rev/9fa81031443b

It appears two values are accessed offthread in nsHttpConnection. While it is unlikely that UpdateMirror and nsHttpConnection::Activate would ever overlap, the possibility is nonzero and could potentially lead to a race.

I'm going to go ahead and land this, and continue to leave the bug open until I remove the suppression.

https://hg.mozilla.org/mozilla-central/rev/b9e5e92b6ea9

https://hg.mozilla.org/mozilla-central/rev/2790e5a95539