C#BackgroundWorker等待结束

我正在处理一个需要用线程完成的项目。

我有一个背景工作者来做这项工作。我想要实现的是，当我点击Button3时，我的后台工作程序将重新启动。我已经试着等待后台工作人员在一段时间内完成Backgroundworker1.IsBusy，但这永远不会结束。当我点击Button3时，我得到错误

此BackgroundWorker当前正忙，无法同时运行多个任务

这是我的代码：

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    }
    private void button1_Click(object sender, EventArgs e)
    {
        backgroundWorker1.RunWorkerAsync();
    }
    private void button2_Click(object sender, EventArgs e)
    {
        backgroundWorker1.CancelAsync();
    }
    private void button3_Click_1(object sender, EventArgs e)
    {
        backgroundWorker1.CancelAsync();
        backgroundWorker1.RunWorkerAsync();
    }
    private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
    {
        BackgroundWorker worker = sender as BackgroundWorker;
        int x = 0, y = 0, result;
        while (true)
        {
            if (backgroundWorker1.CancellationPending)
            {
                e.Cancel = true;
                break;
            }
            else
            {
                x++;
                y++;
                result = x + y;
                this.label1.Invoke(new MethodInvoker(() => this.label1.Text =     result.ToString()));
            }
        }
    }
}//public partial class Form1 : Form

private bool restartOnCancel = false;
private void button3_Click_1(object sender, EventArgs e)
{
    restartOnCancel = true;
    backgroundWorker1.CancelAsync();
}
private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
    if ((e.Cancelled == true) && restartOnCancel)
    {
        restartOnCancel = false;
        backgroundWorker1.RunWorkerAsync();
    }
}