https://crash-stats.mozilla.com/report/index/e0dea993-bf09-4bc4-bfe1-119860180206#allthreads https://crash-stats.mozilla.com/report/index/fae67c93-de78-4229-a591-9a28a0180206#allthreads here 2 crash reports where nsNSSComponent::ShutdownNSS() blocks the main-thread doing something when xpcom-shutdown notification is received. Doing this, other components do not receive the same notifications (for instance workerinternals::RuntimeService) and Fx ends up crashing for timeout. I don't know in which component I should file this bug.

Looks like we try to destroy the session cache while still holding the SSL3 RWLock somewhere.

Franziskus - where else could we be holding the SSL3 RWLock in those crash reports? None of the other stacks are in nss. Could this just be a bug in NSS itself?

Hm, recent logs for that signature look very different from the two linked in comment 0. I didn't find any other logs that would indicate that this is actually a PSM or NSS issue. The only references to NSS are actually NSPR locks. Looks more like a worker locking issue now (bug 1435343).

Yeah I'm not seeing any PSM or NSS hang-crashes with this signature. I'll duplicate this to bug 1435343 for now - we can reopen if this comes back or if fixing that bug doesn't fix this.