ContextSwitch tracing does not work

Development Programming & Scripting
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1

Hello,

we are trying to use the ContextSwitch tracing system to find performance issues. We found that no events of the sort arrive at the insights endpoint. After investigating we found that this check fails because the UserDataLength = 28 while sizeof(FContextSwitchEvent) = 24.

const FContextSwitchEvent* Payload = (const FContextSwitchEvent*)Event->UserData; if (Payload == nullptr || Event->UserDataLength != sizeof(FContextSwitchEvent)) { return; }After looking into the linked documentation for the event we concluded that Microsoft seems to have altered the internal API without updating the documentation?

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Please advise further steps.

Thank you.

2

Steps to Reproduce
Using Visual Studio 2022 14.38.33144 toolchain (C:\Program Files (x86)\Microsoft Visual Studio\2022\BuildTools\VC\Tools\MSVC\14.38.33130) and Windows 10.0.22621.0 SDK (C:\Program Files (x86)\Windows Kits\10)

Start the application using -trace=default,ContextSwitch

3

Hi there,

Firstly, thank for the detailed report and tracking down of the root cause. I’ve asked around, and there does appear to have been a change on Microsoft’s side without a corresponding update to the documentation page.

I’ve filed a bug report on the Unreal Engine side to get this issue tracked, and I will reply with a tracking link when one becomes available.

Best regards,

Chris

4

The tracking link should be Unreal Engine Issues and Bug Tracker (UE\-264913\). It may take a day or two to become visible.

Best regards,

Chris