Profiling .NET MAUI Apps

Local .NET SDK

For most cases when testing PRs or even just for consistency, use the local "install" of dotnet. This can be built using:

dotnet build src/DotNet/DotNet.csproj

In order to use custom packages from a PR:

• make sure the packages exist in an artifacts directory at the root
• update the eng/Versions.props file to that version
• uncomment the <add key="local" value="artifacts" /> in the NuGet.config at the root

Required Tools

Profiling .NET apps require a few tools:

• dotnet tool update -g dotnet-dsrouter --add-source=https://aka.ms/dotnet-tools/index.json
• dotnet tool update -g dotnet-trace --add-source=https://aka.ms/dotnet-tools/index.json

dotnet-dsrouter

The first part that is required is dotnet-dsrouter, which routes traffic from the emulator/device to a socket.

dotnet-dsrouter client-server -tcps 127.0.0.1:9001 -ipcc /tmp/maui-app --verbose debug

This command sets up the router to route data from 127.0.0.1:9001 to /tmp/maui-app.

dotnet-trace

The next part is the trace tool, which reads data from the socket into a file once the app has launched.

dotnet-trace collect --diagnostic-port /tmp/maui-app --format speedscope -o maui-app-trace

This commands converts the trace data into a file from /tmp/maui-app to a maui-app-trace.json file.

Each time the app is launched, the tool will have to be run. Once enough data has been collected, press Enter. This will terminate the trace app and create the trace output file at maui-app-trace.json.

Running the Profiler

Once both tools are running and ready to go, the app can be launched.

To build the profiling app from source, use the local dotnet instance:

./bin/dotnet/dotnet build src/Controls/samples/Controls.Sample.Profiling -f net6.0-android -t:run -c Release -p:IsEmulator=true

This builds the app and runs it on the device/emulator.

The IsEmulator property can be used to control the environment variables of the app. The main reason is that it uses different ports on the Android device depending on whether it is a local emulator or a connected device.

You may have to build the build tasks for the first run:

 ./bin/dotnet/dotnet build Microsoft.Maui.BuildTasks-net6.slnf

Physical Devices

If a physical device is to be used, then there needs to be a port opened on the Android device via adb:

adb reverse tcp:9000 tcp:9001

This commands forwards port 9000 from the device to port 9001 on the host machine.

The same run command can be used for emulators, except that the IsEmulator property should be set to false.

Viewing the results

Once you finish the profiling, there will be a json file named maui-app-trace.json that can be viewed online at: https://www.speedscope.app/

Or, you can use PerfView: https://github.com/microsoft/perfview/releases

Or you can try open it in VS.

Troubleshooting

• If there is broken/missing information in the traces, make sure you are not using the interpreter. Remove the <UseInterpreter> element (or set it to false).