多线程实现动态数组的相乘

/// <summary>
        /// 
        /// </summary>
        /// <param name="Threadnum">线程数</param>
        /// <param name="N">数量级</param>
        private void GetResult(int Threadnum, int N)
        {
            Thread[] threads = new Thread[Threadnum];  //线程数组
            Group[] groups = new Group[Threadnum];  //结果集
            int beginidx = 0;
            int endidx = 0;
            int num = N / Threadnum;
            if (N % Threadnum > 0)  //当不能除尽的时候，每一组多分一个数据
                num += 1;
            for (int i = 0; i < Threadnum; i++)
            {
                beginidx = i * num;
                endidx = (i + 1) * num < N ? (i + 1) * num : N;  //准备数据，起始结束下标  

                groups[i] = new Group(beginidx, endidx); //初始化
                threads[i] = new Thread(groups[i].Run);  
            }

            DateTime dt = DateTime.Now;
            for (int i = 0; i < threads.Length; i++)
            {
                threads[i].Start();  //开启每一个线程工作
            }

            bool IsOver = false;