c# - 应用夏时制和时钟向后移动时，NetworkStream.ReadTimeout无法在NetworkStream.Read(...)上阻塞

我希望有人可以解释这种行为，或者它可能是.NET中的错误。

由于夏时制而使时间向后移动，这意味着NetworkStream无需注意其属性ReadTimeout，并且在此代码的情况下，将导致循环旋转。 (这只是证明它正在发生的一个例子)。

要重现我看到的问题，您需要将其设置为使用夏时制的时区，例如英国。

将您的TimeZone设置为UTC London，并确保选中夏令时。

将日期更改回2017年10月29日

将您的时间设置为01:58:50 am

运行以下代码，并在将夏令时应用于凌晨2点时观看旋转，如果正确应用夏令时，则时间应移回到凌晨1点。

请确保您等待，它可能需要30秒才能开始旋转。

编辑:经过深入调查后，在1个小时后，它停止旋转，行为恢复正常并接受ReadTimeout。

任何想法将不胜感激!

客户代码:

class Program
{
    static bool running = false;

    static void Main(string[] args)
    {
        running = true;
        Task.Factory.StartNew(() => Run());

        Console.ReadKey();

        running = false;
    }


    static void Run()
    {
        TcpClient connection = new TcpClient("127.0.0.1", 1234);

        while (running)
        {
            if (connection != null && connection.Connected)
            {
                try
                {
                    NetworkStream stream = connection.GetStream();
                    stream.ReadTimeout = 1000;

                    byte[] buffer = new byte[1024];
                    int readCount = stream.Read(buffer, 0, 1024); // Should block here for the ReadTimeout duration if nothing received
                                                                  // However when daylight savings is applied and time moves backwards an hour, the stream.ReadTimeout = 1000;
                                                                  // is not honoured and it falls through and spins

                    if (readCount > 0)
                    {
                        Console.WriteLine("Received some data");
                        //process read here
                    }
                    else
                    {
                        Console.WriteLine("ReadTimeout was not honoured");
                    }
                }
                catch (IOException)
                {
                    Console.WriteLine("Read timed out");
                }
            }
        }
    }
}

服务器代码:

class Program
    {
        static bool running = false;

        public static void Main()
        {
            TcpListener server = null;
            try
            {
                // Set the TcpListener on port 13000.
                Int32 port = 5000;
                IPAddress localAddr = IPAddress.Parse("192.168.1.69");

                // TcpListener server = new TcpListener(port);
                server = new TcpListener(localAddr, port);

                // Start listening for client requests.
                server.Start();

                // Enter the listening loop.
                while (true)
                {
                    Console.Write("Waiting for a connection... ");

                    // Perform a blocking call to accept requests.
                    // You could also user server.AcceptSocket() here.
                    TcpClient client = server.AcceptTcpClient();
                    Console.WriteLine("Connected!");


                    // Get a stream object for reading and writing
                    NetworkStream stream = client.GetStream();

                    running = true;

                    Task.Factory.StartNew(() => Run(stream));


                    Console.ReadKey();

                    // Shutdown and end connection
                    client.Close();
                }
            }
            catch (SocketException e)
            {
                Console.WriteLine("SocketException: {0}", e);
            }
            finally
            {
                // Stop listening for new clients.
                server.Stop();
            }


            Console.WriteLine("\nHit enter to continue...");
            Console.Read();
        }

        static async Task Run(NetworkStream stream)
        {
            byte[] stuffToSend = Encoding.ASCII.GetBytes("Stuff to send");
            while (running)
            {
                stream.Write(stuffToSend, 0, stuffToSend.Length);
                await Task.Delay(1000);
            }
        }
    }

最佳答案

.NET ReadTimeout属性中未提及the OS documentation中有一些非常重要的注释:



当前，每次超时后，您都在循环并尝试在同一套接字上进行另一个接收操作。但是，此注释非常清楚，您需要创建一个新的连接。