static void Main(string[] args)        {            Print();            Console.WriteLine("5 :::" + Thread.CurrentThread.ManagedThreadId);            Console.ReadKey();        }        public static async void Print()        {            Console.WriteLine("1 :::" + Thread.CurrentThread.ManagedThreadId);            await PrintAsync();//主线程走到这里的时候并没有返回.所谓返回,是指从当前 async 方法内部返回到调用该方法的位置继续往下执行            Console.WriteLine("8 :::" + Thread.CurrentThread.ManagedThreadId);//由于 PrintAsync() 方法返回的是 tk2,所以这里要等 tk2 执行完毕才会执行.        }        public static Task PrintAsync()        {            Thread.Sleep(2000);            Console.WriteLine("2 :::" + Thread.CurrentThread.ManagedThreadId);            Task tk1 = Task.Run(() =>            {                Thread.Sleep(2000);                Console.WriteLine("6 :::" + Thread.CurrentThread.ManagedThreadId);            });            Console.WriteLine("3 :::" + Thread.CurrentThread.ManagedThreadId);            Task tk2 = Task.Run(() =>            {                Thread.Sleep(5000);                Console.WriteLine("7 :::" + Thread.CurrentThread.ManagedThreadId);            });            Console.WriteLine("4 :::" + Thread.CurrentThread.ManagedThreadId);//主线程走到这里才返回.当然,tk1,tk2 已经开始执行了.            return tk2;        }

 

直接上结果 

 

之前一直理解的是,await 等待的是后面紧跟着的方法,实际等待的是  这个方法返回的 Task 执行完毕,而这个方法里面的非 task 代码依然是同步执行.