C#Winform在SerialPort.Close上卡住

我有一个Winform程序，它在SerialPort上执行一些异步IO。但是，我经常遇到程序卡住SerialPort.Close()调用的问题，这似乎是随机的。

我认为这是线程安全性问题，但是我不确定如何解决。我尝试使用端口打开/关闭功能添加/删除异步DataReceived处理程序，并丢弃端口上的输入和输出缓冲区，但是它似乎没有任何作用。我认为重要的SerialPort代码如下:

using System;
using System.Collections.Generic;
using System.IO.Ports;

public class SerialComm
{
  private object locker = new object();

  private SerialPort port;
  private List<byte> receivedBytes;

  public SerialComm(string portName)
  {
    port = new SerialPort(portName);
    port.BaudRate = 57600;
    port.Parity = Parity.None;
    port.DataBits = 8;
    port.StopBits = StopBits.One;

    receivedBytes = new List<byte>();
  }

  public void OpenPort()
  {
    if(port!=null && !port.IsOpen){
      lock(locker){
        receivedBytes.Clear();
      }

      port.DataReceived += port_DataReceived;
      port.Open();
    }
  }

  public void ClosePort()
  {
    if(port!=null && port.IsOpen){
      port.DataReceived -= port_DataReceived;
      while(!(port.BytesToRead==0 && port.BytesToWrite==0)){
        port.DiscardInBuffer();
        port.DiscardOutBuffer();
      }
      port.Close();
    }
  }

  private void port_DataReceived(object sender, SerialDataReceivedEventArgs e)
  {
    try{
      byte[] buffer = new byte[port.BytesToRead];
      int rcvdBytes = port.Read(buffer, 0, buffer.Length);

      lock(locker){
        receivedBytes.AddRange(buffer);
      }

      //Do the more interesting handling of the receivedBytes list here.

    } catch (Exception ex) {
      System.Diagnostics.Debug.WriteLine(ex.ToString());
      //put other, more interesting error handling here.
    }
  }
}

更新

感谢@Afrin的答案指出了UI线程的死锁情况(This blog post很好地描述了死锁情况，并提供了其他几个不错的技巧)，我做了一个简单的更改，但还无法重现该错误!

private void port_DataReceived(object sender, SerialDataReceivedEventArgs e)
{
  try{
    byte[] buffer = new byte[port.BytesToRead];
    int rcvdBytes = port.Read(buffer, 0, buffer.Length);

    lock(locker){
      receivedBytes.AddRange(buffer);
    }

    ThreadPool.QueueUserWorkItem(handleReceivedBytes);

  } catch (Exception ex) {
    System.Diagnostics.Debug.WriteLine(ex.ToString());
    //put other, more interesting error handling here.
  }
}

private void handleReceivedBytes(object state)
{
  //Do the more interesting handling of the receivedBytes list here.
}

最佳答案

当您关闭它时它会挂起的原因是因为在您的SerialPort对象的事件处理程序中
您正在与主线程同步调用(通常是通过调用invoke)。 SerialPort的close方法等待其EventLoopRunner线程触发激发DataReceived/Error/PinChanged事件的终止。但是由于事件中您自己的代码也正在等待主线程响应，因此您将陷入死锁状态。
解决方案:使用begininvoke而不是invoke:
https://connect.microsoft.com/VisualStudio/feedback/details/202137/serialport-close-hangs-the-application
引用:http://stackoverflow.com/a/3176959/146622
编辑:
Microsoft链接已断开，因为它们已退出Connect。试试web.archive.org:
https://web.archive.org/web/20111210024101/https://connect.microsoft.com/VisualStudio/feedback/details/202137/serialport-close-hangs-the-application

关于C#Winform在SerialPort.Close上卡住，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/8843301/