c# aynsc 和 await

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();

            Console.WriteLine("2 :::" + Thread.CurrentThread.ManagedThreadId);

            Task tk1 = Task.Run(() =>

            {

                Thread.Sleep();

                Console.WriteLine("6 :::" + Thread.CurrentThread.ManagedThreadId);

            });

            Console.WriteLine("3 :::" + Thread.CurrentThread.ManagedThreadId);

            Task tk2 = Task.Run(() =>

            {

                Thread.Sleep();

                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.