A simple helper SynchronizationContext to debug deadlocks

DebugSyncContext.cs

// A helper SynchronizationContext to debug deadlocks by @noseratio
// If you install DebugSyncContext at the very beginning of your console app and run it under debugger,
// it should stop where the deadlock is happening, with a better access to the stack frame.

using System.Diagnostics;

SynchronizationContext.SetSynchronizationContext(new DebugSyncContext());

Console.WriteLine("Hello!");

await Task.Delay(100);
await Task.Delay(200);
await Task.Delay(300);
// break at DebugSyncContext.Wait
Task.Delay(400).GetAwaiter().GetResult(); 
await Task.Delay(500);

Console.WriteLine("Bye!");


class DebugSyncContext: SynchronizationContext
{
    public DebugSyncContext()
    {
        base.SetWaitNotificationRequired();
    }

    public override void Post(SendOrPostCallback d, object? state)
    {
        ThreadPool.QueueUserWorkItem(_ =>
        {
            var sc = SynchronizationContext.Current;
            SynchronizationContext.SetSynchronizationContext(this);
            try
            {
                d(state);
            }
            finally
            {
                SynchronizationContext.SetSynchronizationContext(sc);
            }
        });
    }
    
    public override void Send(SendOrPostCallback d, object? state)
    {
        Debugger.Break();
        throw new NotImplementedException(nameof(Send));
    }

    public override int Wait(nint[] waitHandles, bool waitAll, int millisecondsTimeout)
    {
        Debugger.Break();
        return base.Wait(waitHandles, waitAll, millisecondsTimeout);    
    }
}