public class Program{static void Main(string[] args){ WaitForSimpleNestedTask();Console.WriteLine("=====================================================");SimpleNestedTask();Thread.SpinWait(600000);//等待SimpleNestedTask结束 再运行Console.WriteLine("=====================================================");//SimpleNestedTaskAttachedToParent();
            Console.Read();}static void WaitForSimpleNestedTask(){var outer = Task<int>.Factory.StartNew(() =>{Console.WriteLine("Outer1 task executing.");var nested = Task<int>.Factory.StartNew(() =>{Console.WriteLine("Nested1 task starting.");Thread.SpinWait(5000000);Console.WriteLine("Nested1 task completing.");return 42;});// 父任务等待子任务完成return nested.Result;// 父任务不等待子任务完成//return 1;
            });//输出的时候使用了返回值outer.Result，所以自动等待父任务完成Console.WriteLine("Outer1 has returned {0}.", outer.Result);}static void SimpleNestedTask(){var parent = Task.Factory.StartNew(() =>{Console.WriteLine("Outer2 task executing.");var child = Task.Factory.StartNew(() =>{Console.WriteLine("Nested2 task starting.");Thread.SpinWait(500000);Console.WriteLine("Nested2 task completing.");});});//等待父任务完成，再输出字符串，如果没有这个等待，这句话会先输出
            parent.Wait();Console.WriteLine("Outer2 has completed."); }static void SimpleNestedTaskAttachedToParent(){var parent = Task.Factory.StartNew(() =>{Console.WriteLine("Outer3 task executing.");var child = Task.Factory.StartNew(() =>{Console.WriteLine("Nested3 task starting.");Thread.SpinWait(500000);Console.WriteLine("Nested3 task completing.");}, TaskCreationOptions.AttachedToParent);//增加参数TaskCreationOptions.AttachedToParent，将子任务附加进父任务，这样子任务完成后，父任务才算完成。
            });//等待父任务完成，再输出字符串，如果没有这个等待，这句话会先输出
            parent.Wait();Console.WriteLine("Outer has completed.");}