Benchmark process freeze when running DisassemblyDiagnoserTests with xUnit v3 on macos(x64/arm64)

[filzrev]

I'm trying to update BenchmarkDotNet tests to use xUnit v3. (#3065)

But DisassemblyDiagnoserTests cause freeze and cause CI timeout(6h) when running tests with xUnit v3 on macos(x64/arm64)

It's not happen on following conditions.

1. Running tests on other OS (Windows/Ubuntu).
2. Run benchmark with dotnet run command on macos

So I'm suspecting the issue has caused by SynchronizationContext(xUnit/BenchmarkDotNet) related problem,
But I don't have any proof.

Minimum reproduceable example code
https://github.com/filzrev/test_ci_on_macos

[filzrev]

It seems following DiagnosticsClient::WriteDump method causing timeout.

BenchmarkDotNet/src/BenchmarkDotNet/Disassemblers/ClrMdDisassembler.cs

Lines 59 to 78 in d246230

	if (OsDetector.IsMacOS())
	{
	// ClrMD does not support CreateSnapshotAndAttach on MacOS, and AttachToProcess is unreliable, so we have to create a dump file and load it.
	string dumpPath = Path.GetTempFileName();
	try
	{
	try
	{
	new DiagnosticsClient(processId).WriteDump(DumpType.Full, dumpPath, logDumpGeneration: false);
	}
	catch (ServerErrorException sxe)
	{
	throw new ArgumentException($"Unable to create a snapshot of process {processId:x}.", sxe);
	}
	return DataTarget.LoadDump(dumpPath);
	}
	finally
	{
	File.Delete(dumpPath);
	}

I don't knows why it cause freeze when benchmark running under xUnit v3.

[timcassell]

It sounds like an xUnit or DiagnosticsClient bug. Can you repro with just that code in a test?

[timcassell]

Also can you try updating Microsoft.Diagnostics.NETCore.Client? It looks like the dependent version from ClrMD is quite old now.

Could also try the new 4.0.0-beta.26203.1 version of ClrMD.

[filzrev]

It can be reproduced with simple console application without using BenchmarkDotNet/xUnit.v3/dotnet test

• https://github.com/filzrev/test_ci_on_macos/blob/main/Benchmarks/Tests.cs#L13-L42
• https://github.com/filzrev/test_ci_on_macos/actions/runs/24135008739

On macos(x64/arm64).
WriteDump method stop processing after outputting following logs.

[createdump] 00030bc6 TickFrequency: 1000000 ticks per ms
[createdump] 00030bc6 PAGE_SIZE 4096

It might be there is an issue when creating dump self process on macos environment.

Additionally, I've tries following changes, but it seems there is no behavior differences.

• Create dump with dotnet-dump command.
• Try to use WriteDump/WriteDumpAsync methods
• Update ClrMD and Microsoft.Diagnostics.NETCore.Client versions
• Add ConfigureAwait(false)

[timcassell]

Since you can repro separately, it's clearly an issue with the diagnostics client getting stuck on something from xUnit, nothing we can do here. Please report the bug to dotnet/runtime. You can add a link to the runtime issue in the skip reason.

[filzrev]

I've found createdump on macos issue is tracked by dotnet/runtime#119945.

Dump works as expected when disable AppHost with <UseAppHost>false</UseAppHost> setting.

Though, xunit.v3 requires AppHost existence
It need to skip related benchmarks on macos.