1363453 - The threadHangStats getter causes UI jank

Status: RESOLVED DUPLICATE of bug 1369594

(Toolkit :: Telemetry, defect, P4)

Description

[Florian Quèze [:florian]]

See this profile where the main thread was blocked for 1380ms: https://perfht.ml/2qOEzaR

82% of that time is spent in GetFileVersionInfoSizeW, called with this stack:

GetFileVersionInfoSizeW
GetVersion(wchar_t *)
SharedLibraryInfo::GetInfoForSelf()
mozilla::Telemetry::GetStackAndModules(std::vector<unsigned int,std::allocator<unsigned int> > const &)
`anonymous namespace'::CreateJSHangHistogram
`anonymous namespace'::CreateJSThreadHangStats
`anonymous namespace'::TelemetryImpl::GetThreadHangStats
NS_InvokeByIndex
XPCWrappedNative::CallMethod(XPCCallContext &,XPCWrappedNative::CallMode)
XPC_WN_GetterSetter(JSContext *,unsigned int,JS::Value *)
js::InternalCallOrConstruct(JSContext *,JS::CallArgs const &,js::MaybeConstruct)
js::Call(JSContext *,JS::Handle<JS::Value>,JS::Handle<JS::Value>,js::AnyInvokeArgs const &,JS::MutableHandle<JS::Value>)
CallGetter
GetPropertyOperation
Interpret
js::RunScript(JSContext *,js::RunState &)
assemblePayloadWithMeasurements/payloadObj.threadHangStats<

Comment 1

[Georg Fritzsche [:gfritzsche]]

Markus, do you know about this?
Is Core::Gecko Profiler a suitable component for this?

Comment 2

[Markus Stange [:mstange]]

Core::Gecko Profiler is a suitable component for bugs in SharedLibraryInfo, but I think there's not much we can do about it being slow. I think Telemetry should try to call it on a background thread instead.

Comment 3

[Georg Fritzsche [:gfritzsche]]

Moving this work to a background thread will be more involved.
We can either:
- rework Telemetry ping generation to be in background (hard)
- run on-going background tasks to collect the SharedLibraryInfo
  -> we'd need to confirm that this is "mostly" collecting the data

However, this data is only collected when extended Telemetry is on (i.e. for pre-release and opt-in users).
I doubt this is high-priority for the current efforts, unless its masking some other issues.

Comment 4

[Andrew Overholt [:overholt]]

qf- because it doesn't affect release users. Thanks for the explanation in comment 3, Georg!

Comment 6

[Nika Layzell [:nika] (ni? for response)]

This should be fixed by bug 1369594