This bug was filed from the Socorro interface and is report bp-84b0c900-c4f2-47e6-851b-8c2ae0190102. ============================================================= Top 1 frames of crashing thread: 0 xul.dll nsDOMMutationRecord::Release dom/base/nsDOMMutationObserver.cpp:61 ============================================================= There are 2 crashes (from 1 installation) in nightly 66 with buildid 20190101212914. In analyzing the backtrace, the regression may have been introduced by patch  to fix bug 1514802.  https://hg.mozilla.org/mozilla-central/rev?node=13191d88873d
Both of those are from me. The crash is reproducible but probably only happens in extreme situations like a big MedSpace + LastPass. It was indeed caused by the fix to bug 1514802 (I'll leave the needinfo in case smaug wants to use this bug to land a follow-up).
yup, I'm fixing the issue in a bit different way. MedSpace must be causing insane amount of dom mutations :/
Assignee: nobody → bugs
(In reply to Olli Pettay [:smaug] from comment #2) > MedSpace must be causing insane amount of dom mutations :/ That's probably true.. Unfortunately I think it's not something we fully control as Notes generates a lot of code from the design elements. But that's not something I know for sure yet, and profiling this old code is certainly part of my job description :)
Attachment #9033949 - Flags: review?(continuation) → review+
Pushed by email@example.com: https://hg.mozilla.org/integration/mozilla-inbound/rev/64b2e707cdbd explicitly break down pending mutation record list, r=mccr8
I can confirm that both the hangs and the crashes appear to be gone in today's Nightly!
[Beta/Release Uplift Approval Request] Feature/Bug causing the regression: None User impact if declined: Long CC passes like in bug 1514802 Is this code covered by automated tests?: No Has the fix been verified in Nightly?: Yes Needs manual test from QE?: No If yes, steps to reproduce: bug 1514802 has a testcase. If it hangs, the issue is not fixed List of other uplifts needed: None Risk to taking this patch: Low Why is the change risky/not risky? (and alternatives if risky): Just explicitly clearing a list of objects which is anyhow going to be deleted soon. String changes made/needed: NA
Attachment #9034572 - Flags: approval-mozilla-beta?
Comment on attachment 9034572 [details] [diff] [review] mo_cc_hang_beta.diff [Triage Comment] Fixes some pretty bad hangs as reported in bug 1514802. Approved for 65.0b9.
Attachment #9034572 - Flags: approval-mozilla-beta? → approval-mozilla-beta+
Component: DOM → DOM: Core & HTML
Product: Core → Core
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