1689379 - Crash in [@ shutdownhang | (anonymous namespace)::TrueTypeFontMetricsBuilder::GetBlackBox]

Status: RESOLVED FIXED

(Core :: Graphics: Text, defect)

Description

[Sebastian Hengst [:aryx] (needinfo me if it's about an intermittent or backout)]

All crashes on Windows 7, 90% with x86. More frequent with 86.0b, 85.0b4 was an outlier for that branch with 30 affected installations.

Crash report: https://crash-stats.mozilla.org/report/index/9864abed-1ce5-4277-8634-f9d630210128

MOZ_CRASH Reason: MOZ_CRASH(Shutdown hanging before starting any known phase.)

Top 10 frames of crashing thread:

0 dwrite.dll struct `anonymous namespace'::FontMetricsBuilder::BoundingBox __thiscall `anonymous namespace'::TrueTypeFontMetricsBuilder::GetBlackBox 
1 dwrite.dll virtual struct DesignGlyphMetrics __thiscall `anonymous namespace'::TrueTypeFontMetricsBuilder::GetGlyphMetrics 
2 dwrite.dll void const* __thiscall FontFaceRegionBuilder::Impl::WriteRegionInternal const 
3 dwrite.dll void const* __thiscall FontFaceRegionBuilder::Impl::WriteRegion const 
4 dwrite.dll virtual unsigned int __thiscall FontFaceElement::AddToCacheImpl 
5 dwrite.dll void __thiscall CacheWriter::AddElement 
6 dwrite.dll void __thiscall ClientSideCacheContext::ClientLookup 
7 dwrite.dll virtual void __thiscall ClientSideCacheContext::InitializeElementImpl 
8 dwrite.dll __thiscall DWriteFontFace::DWriteFontFace 
9 dwrite.dll static class ComPtr<class DWriteFontFace> __stdcall DWriteFontFace::CreateFromKey 

Comment 1

[Ryan VanderMeulen [:RyanVM]]

This is showing up in the Beta topcrash list too. Any idea what might be going on here, Jonathan?

Comment 2

[Julien Cristau [:jcristau]]

This was showing up in beta before, now with 89 it's made it to release. Presumably due to bug 1694174.

Comment 3

[Jonathan Kew [:jfkthame]]

It seems like what must be happening is that some time-consuming font calls (DirectWrite APIs can block for a long time if it needs to rebuild its caches etc) are happening while we're trying to shut down. Some of these cases involve the "idle-time" cmap-loader runnable, so it may help if we make it observe will-shutdown notifications and cancel itself. We can also bail out of other potentially-expensive calls like InitializeFamily that may get sent to the parent by a content process right when we've decided to shut down; at that stage there's no real point to completing the requested task anyhow.

I don't think this will necessarily eliminate such crashes entirely, but with luck it should make them less likely. All we can really do, I think, is try pushing such a patch out and see what crash-stats shows...

Comment 4

[Jonathan Kew [:jfkthame]]

Attachment: Bug 1689379 - Try to reduce the chance of an apparent shutdown hang by bailing out of potentially-expensive font-list calls if the app is shutting down. r=lsalzman

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/1397c1d8bde3
Try to reduce the chance of an apparent shutdown hang by bailing out of potentially-expensive font-list calls if the app is shutting down. r=lsalzman

Comment 6

[Noemi Erli[:noemi_erli]]

https://hg.mozilla.org/mozilla-central/rev/1397c1d8bde3

Comment 7

[Jonathan Kew [:jfkthame]]

Comment on attachment 9225000 [details]
Bug 1689379 - Try to reduce the chance of an apparent shutdown hang by bailing out of potentially-expensive font-list calls if the app is shutting down. r=lsalzman

Beta/Release Uplift Approval Request

• User impact if declined: Occasional shutdown crash (killed by the hang detector) on Windows.
• Is this code covered by automated tests?: No
• Has the fix been verified in Nightly?: No
• Needs manual test from QE?: No
• If yes, steps to reproduce:
• List of other uplifts needed: None
• Risk to taking this patch: Low
• Why is the change risky/not risky? (and alternatives if risky): Patch simply bails out of potentially-slow DirectWrite operations if we're in the process of shutting down anyhow; should have no impact during normal use.

(Crash rate on Nightly is too low to reliably show if/how much the patch will help; we won't really see the impact until Beta.)

• String changes made/needed:

Comment 8

[Julien Cristau [:jcristau]]

Comment on attachment 9225000 [details]
Bug 1689379 - Try to reduce the chance of an apparent shutdown hang by bailing out of potentially-expensive font-list calls if the app is shutting down. r=lsalzman

approved for 90.0b5

Comment 9

[Julien Cristau [:jcristau]]

https://hg.mozilla.org/releases/mozilla-beta/rev/a795a41cb3b0

Comment 10

[Julien Cristau [:jcristau]]

Jonathan, should we have another bug for the remaining hangs?

Comment 11

[Jonathan Kew [:jfkthame]]

Yes, that'd probably be good - though I'm not sure how much more we'll be able to do for now, if (as I suspect) the main issue is that sometimes a DirectWrite call that we make ends up blocking for a really long time. But it'd be good to have a bug on file, and take another look at what's left.