Task.WaitAll(task1, task2);//并行执行

//获取返回值第一种task<T>
var t1 = Task.Factory.StartNew<List<string>>(() => { return Run1(); });
t1.Wait();t1.result

//获取返回值第二种
var t1 = Task.Factory.StartNew<List<string>>(() => { return Run1(); });

var t2 = t1.ContinueWith((i) =>  //Continuewith 串行执行，waitall并行执行
         {
             Console.WriteLine("t1集合中返回的个数：" + string.Join(",", i.Result));
         });

async Task<int> TaskOfTResult_MethodAsync()
{
    int hours;
    // . . .
    // Return statement specifies an integer result.
    return hours;
}

// Calls to TaskOfTResult_MethodAsync
Task<int> returnedTaskTResult = TaskOfTResult_MethodAsync();
int intResult = await returnedTaskTResult;
// or, in a single statement
int intResult = await TaskOfTResult_MethodAsync();

// Signature specifies Task
async Task Task_MethodAsync()
{
    // . . .
    // The method has no return statement.  
}

// Calls to Task_MethodAsync
Task returnedTask = Task_MethodAsync();
await returnedTask;
// or, in a single statement
await Task_MethodAsync();

            CancellationTokenSource cts = new CancellationTokenSource();//cts可以共享给任务工厂，同时取消一组任务TaskFactory taskFactory = new TaskFactory();Task[] tasks = new Task[]{taskFactory.StartNew(() => Add(cts.Token)),taskFactory.StartNew(() => Add(cts.Token)),taskFactory.StartNew(() => Add(cts.Token))};//CancellationToken.None指示TasksEnded回调不能被取消taskFactory.ContinueWhenAll(tasks, TasksEnded, CancellationToken.None);Console.ReadKey();//等待按键取消任务cts.Cancel();Console.ReadKey();}static void TasksEnded(Task[] tasks){Console.WriteLine("所有任务已完成！");}

using System;
using System.Threading;
using System.Threading.Tasks;
public class Program {private static Int32 Sum(Int32 n){Int32 sum = 0;for (; n > 0; n--)checked { sum += n; } return sum;}public static void Main() {Task<int32[]> parent = new Task<int32[]>(() => {var results = new Int32[3];   // 创建一个数组存储结果// 创建三个子任务，并进入执行状态new Task(() => results[0] = Sum(100), TaskCreationOptions.AttachedToParent).Start();new Task(() => results[1] = Sum(200), TaskCreationOptions.AttachedToParent).Start();new Task(() => results[2] = Sum(300), TaskCreationOptions.AttachedToParent).Start();// 返回结果集return results;});//当父子任务都执行完毕后，显示结果。这句比较重要，为parent增加了回掉，对parent的结果parentTask.Result==results进行循环显示

        var cwt = parent.ContinueWith(parentTask => Array.ForEach(parentTask.Result, Console.WriteLine));// 开始父任务，子任务将会执行
        parent.Start();cwt.Wait(); // 测试等待回掉效果
    }
}