C# - 无法使用Invoke()从后台线程附加文本进行控制

Question

问候,我在从C#中的工作线程调用richTextBox时遇到问题.我正在使用InvokeRequired/Invoke方法.请看我的代码:

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    }

    private void ThreadSafe(MethodInvoker method)
    {
        if (InvokeRequired)
            Invoke(method);
        else
            method();
    }

    private void WorkerThread(object data)
    {
        string msg = "\nhello, i am thread " + data.ToString();
        ThreadSafe(delegate
        {
            richTextBox1.AppendText(msg);
        });
    }

    private void button1_Click(object sender, EventArgs e)
    {
        Thread[] workers = new Thread[3];

        for (int i = 0; i < 3; i++)
        {
            workers[i] = new Thread(WorkerThread);
            workers[i].Start(i);
            string msg = "\nthread " + i.ToString() + "started!";
            richTextBox1.AppendText(msg);
        }

        int j = 3;
        while (j > 0)
        {
            for (int i = 0; i < 3; i++)
            {
                Thread.Sleep(250);
                richTextBox1.AppendText("\nChecking thread");
                if (workers[i].Join(250))
                {
                    string msg = "\nWorker thread " + i.ToString() + " finished.";
                    richTextBox1.AppendText(msg);
                    workers[i] = null;
                    j--;    // decrement the thread watch count
                }
            }
        }
    }
}

它在富文本框中打印以下内容:

thread 0started!
thread 1started!
thread 2started!
Checking thread
Checking thread
Checking thread
Checking thread
....

它继续,"hello"消息不会被打印,并且UI被冻结.然后我将Invoke()更改为BeginInvoke(),我知道我不应该这样做,然后结果是这样的:

thread 0started!
thread 1started!
thread 2started!
Checking thread
Worker thread 0 finished.
Checking thread
Worker thread 1 finished.
Checking thread
Worker thread 2 finished.
hello, i am thread 0
hello, i am thread 1
hello, i am thread 2

是什么原因,我该怎么办？

提前致谢.

Answer 1

该Invoke方法同步运行您的委托 - 它等待UI线程实际运行它,然后再将控制权返回给调用者.
由于UI线程正在等待线程完成,因此会出现死锁.

相比之下,该BeginInvoke方法异步运行您的委托 - 它立即返回,并且当UI线程空闲时,委托仅运行一段时间.