一、Task 是.NET Framwork 3.0 出现，线程是基于线程池的。

二、创建Task的三种方式　　

        public void TaskMethod()
        {
            Console.WriteLine($"TaskMethod 开始执行,ManagedThreadId：{Thread.CurrentThread.ManagedThreadId}");
            //启动线程
            //1.Task task = new Task(() => Todo("TaskMethod"));
            //task.Start(); 
            {
                Task task = new Task(() => Todo("Task"));
                task.Start();
            }
            //2.Task.Run(() => Todo("TaskMethod"));
            {
                Task.Run(() => Todo("Run"));
            }
            //3.Task.Factory.StartNew(() => Todo("TaskMethod"));
            {
                Task.Factory.StartNew(() => Todo("StartNew"));
            }
            Console.WriteLine($"TaskMethod 开始执行，ManagedThreadId：{Thread.CurrentThread.ManagedThreadId}");
        } 

三、WaitAll  等待所有任务都完成了，在往下执行

       public void TaskWaitAll()
        {
            //WaitAll  等待所有任务都完成了，在往下执行
            List<Task> list = new List<Task>();
            for (int i = 0; i < 10; i++)
            {
                var k = i;
                var task = Task.Run(() =>
                 {
                     Thread.Sleep(500);
                     Console.WriteLine($"show is k ={k},ManagedThreadId={Thread.CurrentThread.ManagedThreadId}");
                 });
                list.Add(task);
            }
            Task.WaitAll(list.ToArray());
            Console.WriteLine("等待中..............");
            Console.WriteLine("等待中..............");
            Console.WriteLine("等待中..............");
            Console.WriteLine("WaitAll执行完了.....");
        } 

四、TaskWaitAny  有一个任务执行完了，就往下执行

public void TaskWaitAny()
        {
            //TaskWaitAny  有一个任务执行完了，就往下执行
            List<Task> list = new List<Task>();
            for (int i = 0; i < 10; i++)
            {
                var k = i;
                var task = Task.Run(() =>
                {
                    Thread.Sleep(500);
                    Console.WriteLine($"show is k ={k},ManagedThreadId={Thread.CurrentThread.ManagedThreadId}");
                });
                list.Add(task);
            }
            Task.WaitAny(list.ToArray());
            Console.WriteLine("等待中..............");
            Console.WriteLine("等待中..............");
            Console.WriteLine("等待中..............");
            Console.WriteLine("WaitAny执行完了.....");
        }

五、WhenAll  等待所有任务都完成了，不阻塞的回调

        public void TaskWhenAll()
        {
            //WhenAll  等待所有任务都完成了，往下执行，不阻塞的回调
            List<Task> list = new List<Task>();
            for (int i = 0; i < 10; i++)
            {
                var k = i;
                var task = Task.Run(() =>
                {
                    Thread.Sleep(1000);
                    Console.WriteLine($"show is k ={k},ManagedThreadId={Thread.CurrentThread.ManagedThreadId}");
                });
                list.Add(task);
            }
            Task.WhenAll(list.ToArray()).ContinueWith(s =>
            {
                Console.WriteLine("等待中..............");
                Console.WriteLine("等待中..............");
                Console.WriteLine("等待中..............");
                Console.WriteLine($"TaskWhenAll执行完了,ManagedThreadId={Thread.CurrentThread.ManagedThreadId}");
            });
        }

六、WhenAny  等待所有任务都完成了，往下执行，不阻塞的回调

        public void TaskWhenAny()
        {
            //WhenAny  等待所有任务都完成了，往下执行，不阻塞的回调
            List<Task> list = new List<Task>();
            for (int i = 0; i < 10; i++)
            {
                var k = i;
                var task = Task.Run(() =>
                {
                    Thread.Sleep(1000);
                    Console.WriteLine($"show is k ={k},ManagedThreadId={Thread.CurrentThread.ManagedThreadId}");
                });
                list.Add(task);
            }
            Task.WhenAny(list.ToArray()).ContinueWith(s =>
            {
                Console.WriteLine("等待中..............");
                Console.WriteLine("等待中..............");
                Console.WriteLine("等待中..............");
                Console.WriteLine($"TaskWhenAny执行完了,ManagedThreadId={Thread.CurrentThread.ManagedThreadId}");
            });
        }    

七、控制并发数量只有20个

        public void ControlThreadNumber()
        {
            List<Task> tasks = new List<Task>();
            for (int i = 0; i < 10000; i++)
            {
                var k = i;
                if (tasks.Count(t => t.Status != TaskStatus.RanToCompletion) >= 20)
                {
                    Task.WaitAny(tasks.ToArray());
                    tasks = tasks.Where(t => t.Status != TaskStatus.RanToCompletion).ToList();
                }
                var task = Task.Run(() =>
                {
                    Thread.Sleep(500);
                    Console.WriteLine($"show is k ={k},ManagedThreadId={Thread.CurrentThread.ManagedThreadId}");
                });
                tasks.Add(task);
            }
        }

八、Sleep和Delay的区别

　　1.Sleep执行时间更长，Delay 执行时间段
　　2.Sleep卡界面，阻塞，Delay 不卡界面，不阻塞
　　3.同步等待，当前线程数等待2S后继续,异步等待，等待2S后启用新线程

　　　　 private void Todo(string name)
        {
            Console.WriteLine($"Todo 方法开始执行....");

            long result = 0;
            for (int i = 0; i < 100000; i++)
            {
                result += i;
            }
            Thread.Sleep(500);
            Console.WriteLine($"Todo方法执行的结果：{result},名称{name}，ManagedThreadId：{Thread.CurrentThread.ManagedThreadId}");

            Console.WriteLine($"Todo 方法结束执行....");
        }