关闭串行端口时，是什么导致我的 UI 冻结?

What causes my UI to freeze when closing a serial port?(关闭串行端口时，是什么导致我的 UI 冻结?)

问题描述

我正在开发一个与串口相关的应用程序.在使用 SerialPort 的 DataReceived 事件时，我需要使用接收到的字节更新文本框:

I am working on a serial port related application. While using DataReceived event of SerialPort I need to update a textbox with the received bytes:

private void Connection_DataReceived(object sender, SerialDataReceivedEventArgs e)
{
    var data = Connection.ReadExisting();
    _readBuffer.Add(indata);

    Invoke(new EventHandler(AddReceivedPacketToTextBox));       
}

所以我使用 Invoke 来更新文本框.但是有一个大问题.当我尝试关闭连接时，我的 UI 被冻结，我认为这是因为 Invoke 可能正在做某事.

So I use Invoke to update the textbox. But there is a big problem. When I try to close connection, my UI gets freezed, I think this is becase Invoke is doing somehing perhaps.

一位朋友说我应该使用 RequiredInvoke，但我不知道他到底在说什么.如何在不搞乱调用和 UI 线程的情况下关闭连接?

A friend said I should use RequiredInvoke, but I have no idea what he ment really. How can I close the connection without messing up the invoke and UI thread?

这是我的关闭方法:

private void DisconnectFromSerialPort()
{
    if (Connection != null && Connection.IsOpen)
    {
        Connection.Close();            
    }
}

更新

正如汉斯所说，我将 Invoke 更改为 BeginInvoke 但现在更糟了，我的应用程序由于 InvalidOperationException 而停止工作，因为集合 _readBuffer 已修改(VS 中的细节是这样说的)

As Hans said I changed Invoke to BeginInvoke but now its a bit worse, my application stops working due to InvalidOperationException because the collection _readBuffer was modified (Thats what the detail says in VS)

这是我将文本添加到文本框的代码:

Here is my code for adding text to textbox:

private void AddReceivedPacketToTextBox(object sender, EventArgs e)
{

    foreach (var i in _readBuffer)
        tbIn.Text += string.Format("{0:X2} ", i);

    tbIn.Text += Environment.NewLine;

    ScrollToBottom(tbIn);

    label4.Text = _receivedPackets.ToString();
    _receivedPackets++;

    _readBuffer.Clear(); //Possibly because clearing collection gets out of sync with BeginInvoke??         
}

第二次更新

我仍然有问题，将 Invoke() 更改为 BeginInvoke 没有帮助.我还尝试添加断开连接以形成关闭事件 nu 成功...每当我关闭我的表单时，它都会获得库存(我的意思是它的父表单，因为这个可以访问串行端口的表单正在从另一个表单调用.

I still have the problem, changing the Invoke() to BeginInvoke didn;t help. I also tried to add disconnect to form closing event nu success...anytime I close my form it gets stock (I mean its parent form, because this form that has access to serialport is being called from another form`.

我的意思是我发现 UI 仅在 2 种情况下被锁定:如果我为调用 Connection.Close() 的按钮计时，如果我尝试关闭表单，父表单将抛出一些对象被释放的异常.

I mean I figured out that the UI gets locked only in 2 cases: If I clock a button which calls Connection.Close() also if I try to close the form, the parent form will throw exception that some objects are disposed.

我从父表单中这样调用串行表单:

I call the serial form like this from the parent form:

public DebugForm DebugForm;

private void button1_Click(object sender, EventArgs e)
{
    if (DebugForm != null)
    {
        DebugForm.BringToFront();
        return;
    }

    DebugForm = new DebugForm();
    DebugForm.StartPosition = FormStartPosition.CenterScreen;
    DebugForm.Closed += delegate
                             {
                                 WindowState = FormWindowState.Normal;
                                 DebugForm = null;
                             };

    DebugForm.Show();
    WindowState = FormWindowState.Minimized; 
}

这会是问题吗?！

推荐答案

这个问题可以通过添加定时器来解决:

The problem could be solved by adding a timer:

  bool formClosing = false;
    private void Connection_DataReceived(object sender, SerialDataReceivedEventArgs e)
    {
      if (formClosing) return;
      _buffer = Connection.ReadExisting();
      Invoke(new EventHandler(AddReceivedPacketToTextBox));
    }
    protected override void OnFormClosing(FormClosingEventArgs e)
    {
      base.OnFormClosing(e);
      if (formClosing) return;
      e.Cancel = true;
      Timer tmr = new Timer();
      tmr.Tick += Tmr_Tick;
      tmr.Start();
      formClosing = true;
    }
    void Tmr_Tick(object sender, EventArgs e)
    {
      ((Timer)sender).Stop();
      this.Close();
    }

感谢 MSDN<的 JohnWein/a>

Thanks to JohnWein from MSDN

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