如何在Form的Closing事件中停止BackgroundWorker？

我知道，唯一的无死锁和异常安全的方法是实际上取消FormClosing事件。如果BGW仍在运行，则设置e.Cancel =
true，并设置一个标志以指示用户请求关闭。然后在BGW的RunWorkerCompleted事件处理程序中检查该标志，并设置Close（）。

private bool closePending;protected override void onFormClosing(FormClosingEventArgs e) {    if (backgroundWorker1.IsBusy) {        closePending = true;        backgroundWorker1.CancelAsync();        e.Cancel = true;        this.Enabled = false;   // or this.Hide()        return;    }    base.onFormClosing(e);}void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e) {    if (closePending) this.Close();    closePending = false;    // etc...}