1319334 - Intermittent dom/workers/test/serviceworkers/test_bug1151916.html | Test timed out.

Status: RESOLVED FIXED

(Core :: DOM: Service Workers, defect)

Description

[Treeherder Bug Filer]

Filed by: philringnalda [at] gmail.com

https://treeherder.mozilla.org/logviewer.html#?job_id=6996546&repo=autoland

https://queue.taskcluster.net/v1/task/LrRQpPicQ4qBWnkhKRHv2A/runs/0/artifacts/public/logs/live_backing.log

Comment 1

[Cătălin Badea (:catalinb)]

This may be another case where we GC a SW instance while waiting for 'statechange' events. I think I managed to reproduce this locally by spamming SpecialPowers.exactGC().

Comment 2

[Cătălin Badea (:catalinb)]

After debugging this further, the problem is when the iframe waits for the worker to become "activated".
The test waits for navigator.serviceWorker.ready to resolve then waits for reg.active.state to become 'activated' using the 'statechange' event.

The problem is that we resolve the ready promise before transitioning the registration's state properties.
So we end up doing this:

1. set mActiveWorker to new worker
2. queue registration change ( .waiting -> .active) - TransitionWaitingToActive();
3. queue state change (activating) - TransitionWaitingToActive();
4. SWM->CheckPendingReadyPromises();
At this point, swInfo->mActiveWorker is non-null, thus we will resolve the pending ready promise.
5. Pending ready promise then callback: here the test will add an event listener using reg.active.onstatechange
6. The runnable queued at step 2 executes and it will set registration.active to registration.waiting.
This will actually clear our reference because, registration.active is non-null because it was accessed when
the pending promise's then-callback was executed, while registration.waiting is null.
7. Cycle collect FTW
8. We never get the 'activated' event.

Comment 3

[Cătălin Badea (:catalinb)]

Attachment: Resolve ready promise *after* updating registration.state properties.

Comment 4

[Ben Kelly [:bkelly, not reviewing]]

Comment on attachment 8813197 [details] [diff] [review]
Resolve ready promise *after* updating registration.state properties.

Review of attachment 8813197 [details] [diff] [review]:
-----------------------------------------------------------------

LGTM, but please write a spec issue and flag it as v1 milestone.  Section 3.4.2 still says:

> 3. If registration’s active worker is null, wait until registration’s active worker changes.
>> Implementers should consider this condition is met when the corresponding registration request gets to the step 6 of Activate algorithm.

This isn't quite right now that step 6 of Activate queues a task to perform the work.

Comment 5

[Cătălin Badea (:catalinb)]

Filed https://github.com/w3c/ServiceWorker/issues/1011 - can't set the milestone, though.

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/1dcdef45d753
Resolve ready promise *after* updating registration.state properties. r=bkelly

Comment 7

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/1dcdef45d753