The MFBT LinkedList destructor asserts it's empty on shutdown, and it seems that sometimes there is a LinkedList being destroyed that still has js::ParseTask instances in it. This is a contributing factor to the high-frequency intermittent failure in bug 1265637, so it would be great if somebody could take a look at how the ParseTask instances are managed and ensure they get cleaned up properly.

A try push showing the failure is at https://treeherder.mozilla.org/#/jobs?repo=try&group_state=expanded&revision=b09bb71cc35359769a76a5dbc9e3f04bf31ab435

It seems this is related to Bug 1652126 ?

Indeed. It looks like the feature discussed in that bug was disabled and then re-enabled on Nightly, and presumably that is responsible for the recent increase in assertion failures.

FWIW, that feature was backed out in a try build by malexandru and the asserts were still present: https://bugzilla.mozilla.org/show_bug.cgi?id=1265637#c166, so I do not think that it's responsible for them, but it may contribute to them.

Yeah, I think there might be multiple places that are leaking items in a LinkedList. I'm trying to track down the others too.

Set release status flags based on info from the regressing bug 1659483

Regressing bug only enabled the feature on nightly.

(deliberately leaving untriaged so the JS triage team automatically revisits this after bug 1652126 is fixed)

This seems to have gone away. Five failures on the 11th, none since.

Presumably this was bug 1652126.