aspnetcore: [SignalR] Initial ping is not guarded with connection lock

Description

It usually (but not always) throws when flushing buffer segments to send a SignalR hub invocation message over named pipe client stream.

• Managed Test: wegylexy/SignalRTunnel/…/src/Test/Test.cs#L145
• NativeAOT Test: wegylexy/SignalRTunnel/…/src/Native/Connection.cs#L145

Coincidentally, they are both line 145 in my code.

Usually:

  Message: 
    System.ArgumentNullException : Value cannot be null. (Parameter 'array')

  Stack Trace: 
    TlsOverPerCoreLockedStacksArrayPool`1.Return(T[] array, Boolean clearArray)
    BufferSegment.ResetMemory()
    StreamPipeWriter.FlushAsyncInternal(Boolean writeToStream, ReadOnlyMemory`1 data, CancellationToken cancellationToken)
    HubConnection.SendHubMessage(ConnectionState connectionState, HubMessage hubMessage, CancellationToken cancellationToken)
    HubConnection.InvokeCore(ConnectionState connectionState, String methodName, InvocationRequest irq, Object[] args, String[] streams, CancellationToken cancellationToken)
    HubConnection.InvokeCoreAsyncCore(String methodName, Type returnType, Object[] args, CancellationToken cancellationToken)
    ForceAsyncAwaiter`1.GetResult()
    HubConnection.InvokeCoreAsync(String methodName, Type returnType, Object[] args, CancellationToken cancellationToken)
    ...

Rarely:

  Message: 
    System.NullReferenceException : Object reference not set to an instance of an object.

  Stack Trace: 
    StreamPipeWriter.FlushAsyncInternal(Boolean writeToStream, ReadOnlyMemory`1 data, CancellationToken cancellationToken)
    HubConnection.SendHubMessage(ConnectionState connectionState, HubMessage hubMessage, CancellationToken cancellationToken)
    HubConnection.InvokeCore(ConnectionState connectionState, String methodName, InvocationRequest irq, Object[] args, String[] streams, CancellationToken cancellationToken)
    HubConnection.InvokeCoreAsyncCore(String methodName, Type returnType, Object[] args, CancellationToken cancellationToken)
    ForceAsyncAwaiter`1.GetResult()
    HubConnection.InvokeCoreAsync(String methodName, Type returnType, Object[] args, CancellationToken cancellationToken)
    ...

Stack reference sources

• dotnet/runtime/…/TlsOverPerCoreLockedStacksArrayPool.cs#L130
• dotnet/runtime/…/BufferSegment.cs#L73
• dotnet/runtime/…/StreamPipeWriter.cs#L313
• dotnet/aspnetcore/…/HubConnection.cs#L868

Configuration

.NET 6 RC1 on Windows 10 (21390) x64, no matter managed or NativeAOT

Regression?

Other information

Server can invoke methods on client via named pipe. It is just client that usually breaks.

Managed and native versions serialize hub invocation arguments differently. Managed version uses official package. Native version uses custom C++ code. Nonetheless, they get written to the buffer successfully, until flushing breaks it.