async-vs-sync.cs

class Program
{
    static void Main(string[] args)
    {
        Sync();
        Async().Wait();
    }

    const int len = 1024 * 16;

    static void Sync()
    {

        var tcpListener = new TcpListener(IPAddress.Loopback, 9999);
        tcpListener.Start();
        var listenerThread = new Thread(() =>
        {
            var buffer = new byte[1024];
            var client = tcpListener.AcceptTcpClient();
            var sp = Stopwatch.StartNew();
            using (var stream = client.GetStream())
            {
                while (true)
                {
                    var read = stream.Read(buffer, 0, 1024);
                    if (read == 0)
                        break;
                }
                Console.WriteLine(sp.Elapsed);
            }
        });
        listenerThread.Start();

        var tcpClient = new TcpClient();
        var sendBuffer = new byte[1024];
        new Random().NextBytes(sendBuffer);
        tcpClient.Connect(new IPEndPoint(IPAddress.Loopback, 9999));
        using (var sendStream = tcpClient.GetStream())
        {
            for (int i = 0; i < len; i++)
            {
                sendStream.Write(sendBuffer, 0, 1024);
            }
        }

        listenerThread.Join();
        tcpListener.Stop();
    }

    static async Task Async()
    {

        var tcpListener = new TcpListener(IPAddress.Loopback, 9999);
        tcpListener.Start();
        var listernerTask = Task.Run(async () =>
        {
            var buffer = new byte[1024];
            var client = await tcpListener.AcceptTcpClientAsync();
            var sp = Stopwatch.StartNew();
            using (var stream = client.GetStream())
            {
                while (true)
                {
                    var read = await stream.ReadAsync(buffer, 0, 1024);
                    if (read == 0)
                        break;
                }
                Console.WriteLine(sp.Elapsed);
            }
        });

        var tcpClient = new TcpClient();
        var sendBuffer = new byte[1024];
        new Random().NextBytes(sendBuffer);
        await tcpClient.ConnectAsync(IPAddress.Loopback, 9999);
        using (var sendStream = tcpClient.GetStream())
        {
            for (int i = 0; i < len; i++)
            {
                await sendStream.WriteAsync(sendBuffer, 0, 1024);
            }
        }

        await listernerTask;
        tcpListener.Stop();
    }
}