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();

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

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

             });

             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