Parallel.ForEach相对于foreach是多线程，并行操作;foreach是单线程品德操作。

  static void Main(string[] args)
        {
            Console.WriteLine("Hello World!");
            List<UserInfo> lst = new List<UserInfo> { };
            UserInfo[] array = new UserInfo[] {};
            for (int i = 1; i <= 10; i++)
            {
                lst.Add(new UserInfo { Age=new Random().Next(1,10),Id=Guid.NewGuid()});
            }
            foreach (var item in lst)
            {
                Console.WriteLine("循环更改前的值："+item.Id+","+item.Age+","+item.Uname);
            }
            array = lst.ToArray();
            //注意Parallel.ForEach 里面传的是数组， MaxDegreeOfParallelism = Environment.ProcessorCount指的是系统有几个cpu就使用几个cpu
            ParallelLoopResult result = Parallel.ForEach(array, new ParallelOptions { MaxDegreeOfParallelism = Environment.ProcessorCount },item =>
            {
                item.Uname = "张" + item.Age;
              
            });
            foreach (var item in array)
            {
                Console.WriteLine("循环更改后的值：" + item.Id + "," + item.Age + "," + item.Uname);
            }
            Console.ReadKey();
        }

  public class UserInfo
    {
        public Guid Id { get; set; }

        public Int32 Age { get; set; }

        public String Uname { get; set; }
    }