Benchmark process freeze when running DisassemblyDiagnoserTests with xUnit v3 on macos(x64/arm64) #3076

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1. filzrev commented on Apr 6, 2026

   

   filzrev

   on Apr 6, 2026

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   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.
2. timcassell commented on Apr 6, 2026

   

   timcassell

   on Apr 6, 2026

   Last edited by timcassell

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   It sounds like an xUnit or DiagnosticsClient bug. Can you repro with just that code in a test?
3. timcassell commented on Apr 6, 2026

   

   timcassell

   on Apr 6, 2026

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   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.
4. filzrev commented on Apr 8, 2026

   

   filzrev

   on Apr 8, 2026

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   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)
5. timcassell commented on Apr 8, 2026

   

   timcassell

   on Apr 8, 2026

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   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.
6. timcassell

   closed this as not plannedon Apr 8, 2026
7. filzrev commented on Apr 9, 2026

   

   filzrev

   on Apr 9, 2026

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   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.

   👍React with 👍1Reacted by Tim Cassell