sync 异步编程

using System;
using System.Net;
using System.Threading;
using System.Threading.Tasks;


namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine($"Main Start...{System.Threading.Thread.CurrentThread.GetHashCode()}");

            var rst = DisplayValueAsync();

            Console.WriteLine($"Main do some thing End...{System.Threading.Thread.CurrentThread.GetHashCode()}");

            Console.WriteLine($"Sub1  End...values is {rst.Result} {System.Threading.Thread.CurrentThread.GetHashCode()}");

            Console.Read();


        }


         public static async Task<int> DisplayValueAsync()
        {
            Console.WriteLine($"Sub call...{System.Threading.Thread.CurrentThread.GetHashCode()}");

           var rst= await Task<int>.Run(()=> {

               System.Threading.Thread.Sleep(2000);

               Console.WriteLine($"Sub exec...{System.Threading.Thread.CurrentThread.GetHashCode()}");


               var random = new Random();
               return random.Next(1,1000);

            });

            return rst;

        }



    }

}

https://www.cnblogs.com/yaopengfei/p/9249390.html

执行异步方法的时候有几个注意事项

1.sync与await要成对出现,异步方法只能有3个返回值 (void Task 与 Task<T>)

2.异步方法内要自行通过task.run开辟新的线程出来

3.主线程通过调用异步方法task.Resutl来获取线程结果,此时也会阻塞线程等待结果