c# - 我如何找到有时会卡住的程序中的错误位置

Question

至少有一两次当我运行我的程序时它卡住了，我不能点击任何按钮甚至关闭它因为表单卡住了。

有时，当我退出(表单关闭)时，程序会卡住。 我已尝试将 try 和 catch 添加到每个方法，但它从未就此停止。

这是我的 Form1 顶部和构造函数:

public partial class Form1 : Form
    {
        private bool quitwithtimer;
        private int y;
        private int x;
        private IntPtr ID;
        private int counter;
        private int minutes;
        private int seconds;
        private DateTime dt;
        [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
        internal static extern bool SetLocalTime(ref SYSTEMTIME lpSystemTime);

        [StructLayout(LayoutKind.Sequential)]
        internal struct SYSTEMTIME
        {
            public ushort wYear;
            public ushort wMonth;
            public ushort wDayOfWeek;    // ignored for the SetLocalTime function
            public ushort wDay;
            public ushort wHour;
            public ushort wMinute;
            public ushort wSecond;
            public ushort wMilliseconds;
        }

        private int day;
        private int month;
        private int year;
        private int hour;
        private int minute;

        public Form1()
        {
            InitializeComponent();

            label1.ForeColor = Color.Red;
            label1.Text = "Test";
            label1.Font = new Font(label1.Font.FontFamily, label1.Font.Size + 8f, label1.Font.Style);
            TimerCount.Text = "00:00";
            quitwithtimer = false;
            x = Screen.PrimaryScreen.Bounds.Bottom - this.Width * 2;
            y = Screen.PrimaryScreen.Bounds.Bottom - this.Height * 2;
            counter = x;
            ID = this.Handle; //get handle of form
            minutes = 5;
            seconds = 0;
        }

        [DllImport("user32.dll", SetLastError = true)]
        internal static extern bool MoveWindow(IntPtr hWnd, int X, int Y, int nWidth, int nHeight, bool bRepaint);

有时可能是这个 DllImport 之一导致问题？

我有这个方法来获取当前时间和日期，但是当程序卡住时，它永远无法捕捉到。

public static DateTime GetNetworkTime()
        {
            DateTime networkDateTime = DateTime.Now;
            try
            {
            IPAddress[] addresses = null;
            //default Windows time server
            const string ntpServer = "time.windows.com";
            const string ntpServer1 = "time.nist.gov";
            const string ntpServer2 = "time-nw.nist.gov";
            const string ntpServer3 = "time-a.nist.gov";
            const string ntpServer4 = "time-b.nist.gov";
            List<string> ntpServersList = new List<string>();
            ntpServersList.Add(ntpServer);
            ntpServersList.Add(ntpServer1);
            ntpServersList.Add(ntpServer2);
            ntpServersList.Add(ntpServer3);
            ntpServersList.Add(ntpServer4);

            // NTP message size - 16 bytes of the digest (RFC 2030)
            var ntpData = new byte[48];

            //Setting the Leap Indicator, Version Number and Mode values
            ntpData[0] = 0x1B; //LI = 0 (no warning), VN = 3 (IPv4 only), Mode = 3 (Client Mode)

            for (int i = 0; i < ntpServersList.Count; i++)
            {
                addresses = Dns.GetHostEntry(ntpServersList[i]).AddressList;
                if (addresses.Length > 0)
                {
                    break;
                }
            }


            //The UDP port number assigned to NTP is 123
            var ipEndPoint = new IPEndPoint(addresses[0], 123);
            //NTP uses UDP
            var socket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);

            socket.Connect(ipEndPoint);

            socket.Send(ntpData);
            socket.Receive(ntpData);
            socket.Close();

            //Offset to get to the "Transmit Timestamp" field (time at which the reply 
            //departed the server for the client, in 64-bit timestamp format."
            const byte serverReplyTime = 40;

            //Get the seconds part
            ulong intPart = BitConverter.ToUInt32(ntpData, serverReplyTime);

            //Get the seconds fraction
            ulong fractPart = BitConverter.ToUInt32(ntpData, serverReplyTime + 4);

            //Convert From big-endian to little-endian
            intPart = SwapEndianness(intPart);
            fractPart = SwapEndianness(fractPart);

            var milliseconds = (intPart * 1000) + ((fractPart * 1000) / 0x100000000L);

            //**UTC** time
            networkDateTime = (new DateTime(1900, 1, 1, 0, 0, 0, DateTimeKind.Utc)).AddMilliseconds((long)milliseconds);
            }
            catch(Exception err)
            {
                MessageBox.Show("error" + err.ToString());
            }
            return networkDateTime.ToLocalTime();
        }

        // stackoverflow.com/a/3294698/162671
        static uint SwapEndianness(ulong x)
        {
            return (uint)(((x & 0x000000ff) << 24) +
                           ((x & 0x0000ff00) << 8) +
                           ((x & 0x00ff0000) >> 8) +
                           ((x & 0xff000000) >> 24));
        }

在运行程序时以及在大多数情况下退出程序时，有时会导致程序卡住一次/两次。

private void Form1_FormClosing(object sender, FormClosingEventArgs e)
        {
            try
            {
                if (MessageBox.Show("Are you sure you want to close the form?", "Close Form",
                   MessageBoxButtons.YesNo, MessageBoxIcon.Question) == DialogResult.No)
                {
                    e.Cancel = true;
                }
                else
                {
                    timer1.Enabled = false;
                    timer2.Enabled = false;
                    ChangeTimeOriginal();
                }
            }
            catch (Exception err)
            {
                MessageBox.Show("Error" + err.ToString());
            }
        }

ChangeTimeOriginal()

private void ChangeTimeOriginal()
        {
            try
            {
                dt = GetNetworkTime();
                day = dt.Day;
                month = dt.Month;
                year = dt.Year;
                hour = dt.Hour;
                minute = dt.Minute;
                SYSTEMTIME time = new SYSTEMTIME();
                time.wDay = (ushort)day;
                time.wMonth = (ushort)month;
                time.wYear = (ushort)year;
                time.wHour = (ushort)hour;
                time.wMinute = (ushort)minute;

                if (!SetLocalTime(ref time))
                {
                    // The native function call failed, so throw an exception
                    throw new Win32Exception(Marshal.GetLastWin32Error());
                }
            }
            catch (Exception err)
            {
                MessageBox.Show("Error" + err.ToString());
            }
        }

我怎样才能找到问题？

编辑**

这就是我在程序卡住和暂停时在右下角的调用堆栈窗口中看到的所有内容。

它转到了行:socket.Receive(ntpData); 在 GetNetworkTime() 方法中。

这是我现在在调用堆栈窗口中看到的:

[External Code] 
>   TestDateTime.exe!TestDateTime.Form1.GetNetworkTime() Line 122 + 0xd bytes   C#
    TestDateTime.exe!TestDateTime.Form1.ChangeTimeOriginal() Line 272 + 0xe bytes   C#
    TestDateTime.exe!TestDateTime.Form1.Form1_FormClosing(object sender, System.Windows.Forms.FormClosingEventArgs e) Line 225 + 0x8 bytes  C#
    [External Code] 
    TestDateTime.exe!TestDateTime.Program.Main() Line 19 + 0x1d bytes   C#
    [External Code] 

Answer 1

您的应用程序卡住的原因似乎是因为您正在调用 GetNetworkTime()，这反过来又会向时间服务器发出 IO 阻塞调用。您应该考虑重新编写此代码以在工作线程上进行这些 IO 阻塞调用。在工作线程上获取结果后，您可以通过 Invoke() 或 BeginInvoke() 构造将此数据传递回 UI 线程。看看this tutorial这应该有所帮助。