Port GREF logging to .NET 6+ EventSource infrastructure

[jonathanpeppers]

Android application type

Android for .NET (net6.0-android, etc.)

Affected platform version

.NET 6

Description

The .NET Podcast app shows dotnet trace output for:

https://github.com/xamarin/xamarin-android/blob/af2875138afada68a870cc803c3e8dcd2e85ff6f/src/Mono.Android/Android.Runtime/AndroidRuntime.cs#L178-L188

https://github.com/xamarin/xamarin-android/blob/af2875138afada68a870cc803c3e8dcd2e85ff6f/src/Mono.Android/Android.Runtime/AndroidRuntime.cs#L206-L211

This logging is almost always disabled, but we call into unmanaged code to increment an integer.

We could ideally port this logging to EventSource and do everything on the managed side -- avoid p/invoke for these.

Steps to Reproduce

Get dotnet trace output for an .NET 6 app.

Did you find any workaround?

No response

Relevant log output

No response

[jonathanpeppers]

FYI this an idea for the future.

[jonpryor]

Time to start writing down some notes…

Collecting Traces

Here is a sample for logging events with EventSource, and then capturing EventSource output: https://learn.microsoft.com/dotnet/core/diagnostics/eventsource-getting-started#log-an-event

The problem is, the Collect and view a trace file section is slightly out of date; it suggests:

dotnet-trace collect --providers Demo -- EventSourceDemo.exe

Problem: .exe files haven't been the output of .NET apps for ages.

So, "obvious alternate is obvious"; "I'll use dotnet run!

dotnet-trace collect --providers Demo -- dotnet run

Problem: that hangs. Oops.

You need to run the .dll directly:

dotnet build
# because I haven't added `$HOME/.dotnet/tools` to $PATH…
$HOME/.dotnet/tools/dotnet-trace collect --providers Demo -- dotnet bin/Debug/net9.0/EventSourceDemo.dll

The above produces a dotnet_*.nettrace file. Nice.

Viewing Traces

How do you view a dotnet_*.trace file? TL;DR: you don't! 🤣

More seriously, dotnet-trace supports Speedscope output:

# do not use
$HOME/.dotnet/tools/dotnet-trace collect --providers Demo \
  --format Speedscope
  -- dotnet bin/Debug/net9.0/EventSourceDemo.dll

The problem is that Speedscope output only contains CPU information, not events!

// SpeedScope handles only CPU samples, events are not support

The Collect and View EventSource Traces documentation mentions

• Visual Studio
• Perfview

Visual Studio errors out for me (?!).

Perfview only runs on Windows.

If we want macOS or Linux support for viewing GREF logs -- and I do! -- then…

I guess I need to use EventPipeTraceEventParser and write my own utility?