dotnet trace missing symbols and broken trace in speedscope output on maccatalyst

[molesmoke]

Description

Attempting to obtain a speedscope file reports a broken stack trace for a MAUI app targeting maccatalyst

Just the default MAUI template app with the sandbox disabled and diagnostics_tracing enabled:

https://github.com/jeremy-visionaid/MauiTestApp/tree/dotnet-trace-broken

A speedscope file is created, but it's unusable since most of the symbols are missing.

dotnet build -f net9.0-maccatalyst -c Debug
dotnet-trace collect --format speedscope -- bin/Debug/net9.0-maccatalyst/maccatalyst-arm64/MauiTestApp.app/Contents/MacOS/MauiTestApp

Configuration

macOS 15.5
ARM64
MAUI MacCatalyst app

.NET SDK:
 Version:           9.0.302
 Commit:            bb2550b9af
 Workload version:  9.0.300-manifests.183aaee6
 MSBuild version:   17.14.13+65391c53b

Runtime Environment:
 OS Name:     Mac OS X
 OS Version:  15.5
 OS Platform: Darwin
 RID:         osx-arm64
 Base Path:   /usr/local/share/dotnet/sdk/9.0.302/

.NET workloads installed:
 [macos]
   Installation Source: SDK 9.0.300
   Manifest Version:    15.5.9207/9.0.100
   Manifest Path:       /usr/local/share/dotnet/sdk-manifests/9.0.100/microsoft.net.sdk.macos/15.5.9207/WorkloadManifest.json
   Install Type:        FileBased

 [maui-tizen]
   Installation Source: SDK 9.0.300
   Manifest Version:    9.0.51/9.0.100
   Manifest Path:       /usr/local/share/dotnet/sdk-manifests/9.0.100/microsoft.net.sdk.maui/9.0.51/WorkloadManifest.json
   Install Type:        FileBased

 [maui-maccatalyst]
   Installation Source: SDK 9.0.300
   Manifest Version:    9.0.51/9.0.100
   Manifest Path:       /usr/local/share/dotnet/sdk-manifests/9.0.100/microsoft.net.sdk.maui/9.0.51/WorkloadManifest.json
   Install Type:        FileBased

 [maui-ios]
   Installation Source: SDK 9.0.300
   Manifest Version:    9.0.51/9.0.100
   Manifest Path:       /usr/local/share/dotnet/sdk-manifests/9.0.100/microsoft.net.sdk.maui/9.0.51/WorkloadManifest.json
   Install Type:        FileBased

 [ios]
   Installation Source: SDK 9.0.300
   Manifest Version:    18.5.9207/9.0.100
   Manifest Path:       /usr/local/share/dotnet/sdk-manifests/9.0.100/microsoft.net.sdk.ios/18.5.9207/WorkloadManifest.json
   Install Type:        FileBased

 [maccatalyst]
   Installation Source: SDK 9.0.300
   Manifest Version:    18.5.9207/9.0.100
   Manifest Path:       /usr/local/share/dotnet/sdk-manifests/9.0.100/microsoft.net.sdk.maccatalyst/18.5.9207/WorkloadManifest.json
   Install Type:        FileBased

 [android]
   Installation Source: SDK 9.0.300
   Manifest Version:    35.0.78/9.0.100
   Manifest Path:       /usr/local/share/dotnet/sdk-manifests/9.0.100/microsoft.net.sdk.android/35.0.78/WorkloadManifest.json
   Install Type:        FileBased

Configured to use loose manifests when installing new manifests.

Host:
  Version:      9.0.7
  Architecture: arm64
  Commit:       3c298d9f00

.NET SDKs installed:
  9.0.302 [/usr/local/share/dotnet/sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.App 9.0.7 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 6.0.36 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 9.0.7 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]

Other architectures found:
  None

Environment variables:
  Not set

global.json file:
  Not found

Learn more:
  https://aka.ms/dotnet/info

Download .NET:
  https://aka.ms/dotnet/download

Regression?

Other information

dotnet-trace collect --format speedscope -- bin/Debug/net9.0-maccatalyst/maccatalyst-arm64/MauiTestApp.app/Contents/MacOS/MauiTestApp
No profile or providers specified, defaulting to trace profile 'cpu-sampling'

Provider Name                           Keywords            Level               Enabled By
Microsoft-DotNETCore-SampleProfiler     0x0000F00000000000  Informational(4)    --profile 
Microsoft-Windows-DotNETRuntime         0x00000014C14FCCBD  Informational(4)    --profile 

Launching: bin/Debug/net9.0-maccatalyst/maccatalyst-arm64/MauiTestApp.app/Contents/MacOS/MauiTestApp 
Process        : /Users/jeremy/src/tests/MauiTestApp/MauiTestApp/bin/Debug/net9.0-maccatalyst/maccatalyst-arm64/MauiTestApp.app/Contents/MacOS/MauiTestApp
Output File    : /Users/jeremy/src/tests/MauiTestApp/MauiTestApp/MauiTestApp_20250728_153520.nettrace

[00:00:00:19]	Recording trace 5.3804   (MB)
Press <Enter> or <Ctrl+C> to exit...

Trace completed.
Processing trace data file '/Users/jeremy/src/tests/MauiTestApp/MauiTestApp/MauiTestApp_20250728_153520.nettrace' to create a new Speedscope file '/Users/jeremy/src/tests/MauiTestApp/MauiTestApp/MauiTestApp_20250728_153520.speedscope.json'.
Detected a potentially broken trace. Continuing with best-efforts to convert the trace, but resulting speedscope file may contain broken stacks as a result.
Conversion complete
Process exited with code '0'.

[mdh1418]

@molesmoke What version of dotnet-trace are you using? If you are using v9.0.621003 and used ctrl+c to stop the trace, it is likely that you are hitting the scenario that #5519 addressed (which hasn't had a release yet). If it is that scenario, the previous verison v9.0.607501 should work

[molesmoke]

Thanks! I meant to add that I'd seen that issue and had already tried downgrading to v9.0.607501, but the issue persists:

dotnet-trace --version
9.0.607501+a651406e39038aef1dbc7c8097b52953284dba27

But your comment made me go back and double check, and one approach does actually work, I find:

1. The application exiting normally - broken trace
2. dotnet-trace Ctrl+C - broken trace
3. dotnet-trace Enter - trace works!

So it, seems I have a workaround were I could make the app sleep after the bit I want to profile is complete and make sure to use Enter to stop the trace. But yes, this appears to be a different issue to #5519

[hoyosjs]

One thing that can help us @molesmoke - ca you please run your scenario after upgrading the tool with dotnet tool update -g dotnet-trace --add-source "https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-tools/nuget/v3/index.json"? That will get you the nightly version of the tool installed and will help us determine if fixes to termination and ctrl-c handlers cover your scenario.

[molesmoke]

Thanks again! I tried out 9.0.637901 from the dnceng feed, but pretty similar results:

1. Application exits cleanly - broken trace
2. dotnet-trace Ctrl+C - broken trace (and speedscope file not created - have to manually convert the nettrace file)
3. dotnet-trace Enter - trace works

[lateralusX]

So does this mean that you get a nettrace file that is correct, just that the conversion to speedscope didn't work as part of the same dotnet-trace execution, but convert the previous captured nettrace file actually successfully converted to speedscope in next execution of dotnet-trace convert command? The fix #5519 wouldn't always get you to "Trace completed." because it signal handler would have killed dotnet-trace, that PR fix that scenario. If you get a correct nettrace file on disk, then session has correctly been stopped and all data flushed to disk so then there is some issue with the post step converting to speedscope when there is a pending cancelation.

[lateralusX]

I see that you run the app as a child process using --, that won't work since ctrl+c will be passed to the child process the will be terminated and if the app doesn't handle signals and shutdown gracefully you will get a truncated trace since the open sessions won't be properly closed.

[mdh1418]

Talked with lateralusX offline, it seems like Maccatalyst apps might not handle shutdown logic properly by default, and the app will just close. For what it's worth, I added a timeout that invokes Environment.Exit after 5s in addition to SIGINT (ctrl+c) handling to the default Maui app on .NET 9, and using the nightly build that hoyosjs.
All three scenarios (Application Exits, dotnet-trace Ctrl+C, dotnet-trace Enter) seem to complete the speedscope/trace generation successfully.

using System.Timers;
using System.Runtime.InteropServices;

namespace MyMauiApp;

public partial class MainPage : ContentPage
{
	int count = 0;
	private System.Timers.Timer? _closeTimer;
	
#if MACCATALYST
	// P/Invoke declarations for Unix signal handling
	[DllImport("libc", SetLastError = true)]
	private static extern IntPtr signal(int signum, SignalHandler handler);
	
	private delegate void SignalHandler(int signal);
	private static SignalHandler? _signalHandler;
	
	private const int SIGINT = 2; // Ctrl+C
	private const int SIGTERM = 15; // Termination signal
#endif

	public MainPage()
	{
		InitializeComponent();

		// Set up Ctrl+C signal handling
		SetupSignalHandling();

		// Start a timer to close the app after 5 seconds
		StartCloseTimer();
	}

	private void SetupSignalHandling()
	{
#if MACCATALYST
		// Use P/Invoke to register Unix signal handlers
		_signalHandler = OnUnixSignal;
		
		// Register for SIGINT (Ctrl+C) and SIGTERM
		signal(SIGINT, _signalHandler);
		signal(SIGTERM, _signalHandler);
		
		// Also register process exit handler as backup
		AppDomain.CurrentDomain.ProcessExit += OnProcessExit;
		
		Console.WriteLine("Unix signal handlers registered for SIGINT (Ctrl+C) and SIGTERM");
		Console.WriteLine("Press Ctrl+C to test signal handling");
#else
		// Handle Ctrl+C (SIGINT) signal on other platforms
		Console.CancelKeyPress += OnCancelKeyPress;
		AppDomain.CurrentDomain.ProcessExit += OnProcessExit;
		Console.WriteLine("Ctrl+C signal handler registered. Press Ctrl+C for graceful shutdown.");
#endif
	}

#if MACCATALYST
	private static void OnUnixSignal(int signal)
	{
		Console.WriteLine($"\nUnix signal {signal} received!");
		
		if (signal == SIGINT)
		{
			Console.WriteLine("SIGINT (Ctrl+C) detected! Performing graceful shutdown...");
		}
		else if (signal == SIGTERM)
		{
			Console.WriteLine("SIGTERM detected! Performing graceful shutdown...");
		}
		
		Console.WriteLine("Cleaning up resources...");
		
		// Give a moment for cleanup
		Task.Delay(1000).Wait();
		
		Console.WriteLine("Graceful shutdown complete. Exiting...");
		Environment.Exit(0);
	}
#endif

#if !MACCATALYST
	private void OnCancelKeyPress(object? sender, ConsoleCancelEventArgs e)
	{
		// Handle Ctrl+C signal
		e.Cancel = true; // Prevent immediate termination
		
		Console.WriteLine("\nCtrl+C detected! Performing graceful shutdown...");
		Console.WriteLine("Cleaning up resources...");
		
		// Cleanup on main thread
		MainThread.BeginInvokeOnMainThread(async () =>
		{
			await Task.Delay(1000); // Give time for cleanup
			Console.WriteLine("Graceful shutdown complete. Exiting...");
			Environment.Exit(0);
		});
	}
#endif

	private void OnProcessExit(object? sender, EventArgs e)
	{
		// Cleanup when process is exiting
		Console.WriteLine("Process exit detected. Performing cleanup...");
		_closeTimer?.Stop();
		_closeTimer?.Dispose();
		Console.WriteLine("Cleanup complete.");
	}

	private void StartCloseTimer()
	{
		_closeTimer = new System.Timers.Timer(5000); // 5 seconds
		_closeTimer.Elapsed += OnCloseTimerElapsed;
		_closeTimer.AutoReset = false; // Only fire once
		_closeTimer.Start();
		
		// Print to console instead of showing alert
		Console.WriteLine("Auto-close timer started. App will close automatically in 5 seconds.");
	}

	private void OnCloseTimerElapsed(object? sender, ElapsedEventArgs e)
	{
		MainThread.BeginInvokeOnMainThread(() =>
		{
			CloseApp();
		});
	}

	private void CloseApp()
	{
		try
		{
			// Direct exit - works when sandbox is disabled
			Console.WriteLine("Auto-close timer elapsed. Closing app...");
			Environment.Exit(0);
		}
		catch (Exception ex)
		{
			// If that fails, print error to console
			Console.WriteLine($"Error: Could not close app automatically: {ex.Message}");
		}
	}

	// Override the OnAppearing method
	protected override void OnAppearing()
	{
		base.OnAppearing();
		
		// Add a simple status toolbar item
		var statusToolbarItem = new ToolbarItem
		{
			Text = "Press Ctrl+C to exit",
			Order = ToolbarItemOrder.Primary
		};
		
		this.ToolbarItems.Add(statusToolbarItem);
	}

	protected override void OnDisappearing()
	{
		base.OnDisappearing();
		
		// Clean up the timer
		_closeTimer?.Stop();
		_closeTimer?.Dispose();
		_closeTimer = null;
		
		// Unregister signal handlers
#if !MACCATALYST
		Console.CancelKeyPress -= OnCancelKeyPress;
#endif
		AppDomain.CurrentDomain.ProcessExit -= OnProcessExit;
	}

	private void OnCounterClicked(object? sender, EventArgs e)
	{
		count++;

		if (count == 1)
			CounterBtn.Text = $"Clicked {count} time";
		else
			CounterBtn.Text = $"Clicked {count} times";

		SemanticScreenReader.Announce(CounterBtn.Text);
	}
}

[molesmoke]

Oh,Environment.Exit fixes it, thanks! If the Main function terminates normally then the trace is broken, but if you exit with Environment.Exit(0) then it's OK. So, all that's required to fix profiling for maccatalyst is this:

        static void Main(string[] args)
        {
            // if you want to use a different Application Delegate class from "AppDelegate"
            // you can specify it here.
            SomeProfilingStuff();
            Environment.Exit(0); 
        }

Interestingly, changing Main to return 0 still gives a broken trace, and pressing the Close button in the app bypasses exiting via Main (UIApplication.Main(args, null, typeof(AppDelegate)); does not return).

Maybe some guru from macios or the runtime team might know if something is broken there or it's a known limitation... Any thoughts @rolfbjarne?

Anyways, at least using Enviroment.Exit and either the old (v9.0.607501) or pre-release dotnet-trace is sufficient to allow some decent profiling.

The last piece I'm missing is how to get things running in release? The following was insufficient:

	<ItemGroup>
		<_MonoComponent Include="diagnostics_tracing" />
	</ItemGroup>

>dotnet-trace collect --format speedscope -- bin/Release/net9.0-maccatalyst/maccatalyst-arm64/MauiTestApp.app/Contents/MacOS/MauiTestApp
No profile or providers specified, defaulting to trace profile 'cpu-sampling'

Provider Name                           Keywords            Level               Enabled By
Microsoft-DotNETCore-SampleProfiler     0x0000F00000000000  Informational(4)    --profile 
Microsoft-Windows-DotNETRuntime         0x00000014C14FCCBD  Informational(4)    --profile 

Launching: bin/Release/net9.0-maccatalyst/maccatalyst-arm64/MauiTestApp.app/Contents/MacOS/MauiTestApp 
Unable to start tracing session - the target app failed to connect to the diagnostics port. This may happen if the target application is running .NET Core 3.1 or older versions. Attaching at startup is only available from .NET 5.0 or later.
[ERROR] System.TimeoutException: The operation has timed out.
   at Microsoft.Diagnostics.NETCore.Client.HandleableCollection`1.Handle(Handler handler, TimeSpan timeout) in /_/src/Microsoft.Diagnostics.NETCore.Client/HandleableCollection.cs:line 155
   at Microsoft.Diagnostics.NETCore.Client.HandleableCollection`1.Handle(TimeSpan timeout) in /_/src/Microsoft.Diagnostics.NETCore.Client/HandleableCollection.cs:line 130
   at Microsoft.Diagnostics.NETCore.Client.ReversedDiagnosticsServer.Accept(TimeSpan timeout) in /_/src/Microsoft.Diagnostics.NETCore.Client/ReversedServer/ReversedDiagnosticsServer.cs:line 192
   at Microsoft.Internal.Common.Utils.DiagnosticsClientBuilder.Build(CancellationToken ct, Int32 processId, String diagnosticPort, Boolean showChildIO, Boolean printLaunchCommand) in /_/src/Tools/Common/ReversedServerHelpers/ReversedServerHelpers.cs:line 242
   at Microsoft.Diagnostics.Tools.Trace.CollectCommandHandler.Collect(CancellationToken ct, CommandLineConfiguration cliConfig, Int32 processId, FileInfo output, UInt32 buffersize, String providers, String profile, TraceFileFormat format, TimeSpan duration, String clrevents, String clreventlevel, String name, String diagnosticPort, Boolean showchildio, Boolean resumeRuntime, String stoppingEventProviderName, String stoppingEventEventName, String stoppingEventPayloadFilter, Nullable`1 rundown, String dsrouter) in /_/src/Tools/dotnet-trace/CommandLine/Commands/CollectCommand.cs:line 221

[rolfbjarne]

Maybe some guru from macios or the runtime team might know if something is broken there or it's a known limitation... Any thoughts @rolfbjarne?

This seems like a runtime issue, if Environment.Exit(0) works when just returning from Main doesn't.

pressing the Close button in the app bypasses exiting via Main (UIApplication.Main(args, null, typeof(AppDelegate)); does not return).

IIRC macOS calls exit(0) when hitting the close button.

The runtime might be able to do something here (install an atexit handler to flush stuff?).

The last piece I'm missing is how to get things running in release? The following was insufficient:

	<ItemGroup>
		<_MonoComponent Include="diagnostics_tracing" />
	</ItemGroup>

Is the sandbox enabled for your app? If so, see the last part of this comment: dotnet/runtime#96970 (comment)

[lateralusX]

@rolfbjarne This sound like an embedding issue, runtime has a cleanup function that needs to be called to correctly shutdown the runtime, including closing any pending sessions, mono_jit_cleanup, doesn't macos call the embedding API's to correctly shutdown runtime after main returns or before calling other APIs to terminate the app?

[molesmoke]

Is the sandbox enabled for your app? If so, see the last part of this comment: dotnet/runtime#96970 (comment)

@rolfbjarne Thanks for weighing in! Yes, I based my approach off that thread. Sandbox is disabled, otherwise it doesn't work at all

[rolfbjarne]

@rolfbjarne This sound like an embedding issue, runtime has a cleanup function that needs to be called to correctly shutdown the runtime, including closing any pending sessions, mono_jit_cleanup, doesn't macos call the embedding API's to correctly shutdown runtime after main returns or before calling other APIs to terminate the app?

Looks like we don't. Fix in progress: dotnet/macios#23446