Occasional crash during gcdump

Start in src/Tools/dotnet-gcdump/DotNetHeapDump/EventPipeDotNetHeapDumper.cs at lines 269 and 274, then compare the full log with the caller in HeapDumper.cs at line 103. Investigate the StreamWriter exception, Task.WaitAll path, and subsequent “RootIndex not set” error; done means the failure cause is identified and gcdump behavior is verified against the reported scenario.

Our tools run the same logic as the dotnet-gcdump tool. It occasionally crashes on macOS (default GitHub Actions Runner image) with the stack trace below. Related code:

var heapInfo = new DotNetHeapInfo();
var memoryGraph = new MemoryGraph(50_000);

if (EventPipeDotNetHeapDumper.DumpFromEventPipe(cancellationToken, processId, null,
    memoryGraph, logWriter, 30, heapInfo))
{
    memoryGraph.AllowReading();
    GCHeapDump.WriteMemoryGraph(memoryGraph, outputPath, "dotnet-gcdump");
    return true;
}

Stack trace of the crash:

  0.5s: EventPipe Listener dying
  0.5s: [Error] Exception during gcdump: System.AggregateException: One or more errors occurred. (Specified argument was out of the range of valid values.)
 ---> System.ArgumentOutOfRangeException: Specified argument was out of the range of valid values.
   at System.IO.StreamWriter.Flush(Boolean flushStream, Boolean flushEncoder)
   at System.IO.StreamWriter.WriteFormatHelper(String format, ReadOnlySpan`1 args, Boolean appendNewLine)
   at System.IO.StreamWriter.WriteLine(String format, Object arg0)
   at Microsoft.Diagnostics.Tools.GCDump.EventPipeDotNetHeapDumper.<>c__DisplayClass3_1.<DumpFromEventPipe>b__5() in /_/src/Tools/dotnet-gcdump/DotNetHeapDump/EventPipeDotNetHeapDumper.cs:line 269
   at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)
--- End of stack trace from previous location ---
   at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot, Thread threadPoolThread)
   --- End of inner exception stack trace ---
   at System.Threading.Tasks.Task.WaitAllCore(ReadOnlySpan`1 tasks, Int32 millisecondsTimeout, CancellationToken cancellationToken)
   at System.Threading.Tasks.Task.WaitAll(Task[] tasks, Int32 millisecondsTimeout)
   at Microsoft.Diagnostics.Tools.GCDump.EventPipeDotNetHeapDumper.DumpFromEventPipe(CancellationToken ct, Int32 processId, String diagnosticPort, MemoryGraph memoryGraph, TextWriter log, Int32 timeout, DotNetHeapInfo dotNetInfo) in /_/src/Tools/dotnet-gcdump/DotNetHeapDump/EventPipeDotNetHeapDumper.cs:line 274
[  0.5s: Done Dumping .NET heap success=True]

---- System.ApplicationException : RootIndex not set.

This is nearly impossible to reproduce for us.

Full log at: https://github.com/SteeltoeOSS/Steeltoe/actions/runs/34455238672/job/102799980981.
Full source code at: https://github.com/SteeltoeOSS/Steeltoe/blob/main/src/Management/src/Endpoint/Actuators/HeapDump/HeapDumper.cs#L103

Any thoughts on what could be causing this, or where to look further?