线程循环


//开始获取线程
        private void btn_start_Click(object sender, EventArgs e)
        {
            if (tCompare != null)
            {
                tCompare.Start();
            }
            else
            {
                tCompare = new Thread(new ThreadStart(compare));
                tCompare.IsBackground = true;
                tCompare.Start();
            }
        }
//无限循环，当到达指定的时间点后（每天），便开始执行线程（从网页抓取数据）
        public void compare()
        {
            while (1 == 1)
            {
                Application.DoEvents();
                System.DateTime currentTime = new System.DateTime();
                currentTime = System.DateTime.Now;
                int iHour = currentTime.Hour;//当前 时
                int iMinute = currentTime.Minute;//当前 分 
                int iSecond = currentTime.Second;// 当前 秒                int xHour = int.Parse(tb_hour.Text);//设定 时
                int xMinute = int.Parse(tb_minute.Text);//设定 分
                int xSecond = int.Parse(tb_second.Text);//设定 秒
                if (iHour == xHour && iMinute == xMinute && iSecond == xSecond)//到达指定时间，启动4个线程
                {
                    currcount = 0;
                    if (tGetHtml1 != null)
                    {
                        tGetHtml1.Start();
                    }
                    else
                    {
                        tGetHtml1 = new Thread(new ThreadStart(GetHtml));
                        tGetHtml1.IsBackground = true;
                        tGetHtml1.Start();
                        System.Threading.Thread.Sleep(200);
                    }                    if (tGetHtml2 != null)
                    {
                        tGetHtml2.Start();
                    }
                    else
                    {
                        tGetHtml2 = new Thread(new ThreadStart(GetHtml));
                        tGetHtml2.IsBackground = true;
                        tGetHtml2.Start();
                        System.Threading.Thread.Sleep(200);
                    }                    if (tGetHtml3 != null)
                    {
                        tGetHtml3.Start();
                    }
                    else
                    {
                        tGetHtml3 = new Thread(new ThreadStart(GetHtml));
                        tGetHtml3.IsBackground = true;
                        tGetHtml3.Start();
                        System.Threading.Thread.Sleep(200);
                    }                    if (tGetHtml4 != null)
                    {
                        tGetHtml4.Start();
                    }
                    else
                    {
                        tGetHtml4 = new Thread(new ThreadStart(GetHtml));
                        tGetHtml4.IsBackground = true;
                        tGetHtml4.Start();
                        System.Threading.Thread.Sleep(200);
                    }                }
                else
                {
                    Thread.Sleep(1000);
                }
            }
        }
//从网页抓取数据
        public void GetHtml()
        {
          //抓取过程
          break;
         }//退出
        private void FlightGet_FormClosing(object sender, FormClosingEventArgs e)
        {
            if (MessageBox.Show("确定关闭？", "关闭确认", MessageBoxButtons.OKCancel, MessageBoxIcon.Question) != DialogResult.OK)
            {
                e.Cancel = true;
            }
            else
            {
                if (tCompare != null)
                {
                    tCompare.Abort();
                }
                if (tGetHtml1 != null)
                {
                    tGetHtml1.Abort();
                }
                if (tGetHtml2 != null)
                {
                    tGetHtml2.Abort();
                }
                if (tGetHtml3 != null)
                {
                    tGetHtml3.Abort();
                }
                if (tGetHtml3 != null)
                {
                    tGetHtml4.Abort();
                }
            
            }
        }
说明：实际上，是开启了10个线程去取数据。由于数据量比较大，所以必须用多个线程。现在的情况是：程序可以执行一次，可以正常关闭，但是无法实现循环执行，也就是在第二次到达指定的时间时，程序会出错。怎么解决呢？望各位高手不吝赐教。