c#Parallel.ForEach控制线程数量

 List<int> listI = new List<int>();
                for (int i = 0; i < 1000; i++)
                {
                    listI.Add(i);
                }
                ParallelOptions options = new ParallelOptions();
                options.MaxDegreeOfParallelism = 3;//支持3个并发执行
                Parallel.ForEach(listI, options, x => Dosome("Exec:" + x));

  public static void Dosome(string str)
        {
            Thread.Sleep(1000);
            Console.WriteLine(str + "datetime.now" + DateTime.Now);
        }