AttachedToParent任务混乱

我在理解AttachedToParent参数如何工作时遇到了问题.

以下是示例代码:

public static void Main(string[] args)
    {
        Task parentTask = Task.Run(()=> 
        {
            int[] results = new int[3];

            Task t1 = new Task(() => { Thread.Sleep(3000); results[0] = 0; }, TaskCreationOptions.AttachedToParent);
            Task t2 = new Task(() => { Thread.Sleep(3000); results[1] = 1; }, TaskCreationOptions.AttachedToParent);
            Task t3 = new Task(() => { Thread.Sleep(3000); results[2] = 2; }, TaskCreationOptions.AttachedToParent);

            t1.Start();
            t2.Start();
            t3.Start();

            return results;
        });

        Task finalTask = parentTask.ContinueWith(parent =>
        {
            foreach (int result in parent.Result)
            {
                Console.WriteLine(result);
            }
        });

        finalTask.Wait();
        Console.ReadLine();
    }

据我所知,当一个Task有子任务时,父任务在所有子任务都准备就绪时结束.此示例的问题是输出如下所示:

0
0
0

这意味着父Task没有等待其子任务完成.获得有效结果的唯一方法0 1 2是在所有子Taks上使用Wait,在return results;语句之前添加一些这样的代码:

Task[] taskList = { t1, t2, t3 };
Task.WaitAll(taskList);

我的问题是这个.为什么TaskCreationOptions.AttachedToParent我们还必须为每个子任务手动调用Wait方法？

编辑:

当我写这个问题的时候,我已经改变了一点代码,现在AttachedToParent工作得很好.唯一的区别是我用过parentTask.Start();而不是用Task.Run();.

public static void Main(string[] args)
    {
        Task parentTask = new Task(()=> 
        {
            int[] results = new int[3];

            Task t1 = new Task(() => { Thread.Sleep(3000); results[0] = 0; }, TaskCreationOptions.AttachedToParent);
            Task t2 = new Task(() => { Thread.Sleep(3000); results[1] = 1; }, TaskCreationOptions.AttachedToParent);
            Task t3 = new Task(() => { Thread.Sleep(3000); results[2] = 2; }, TaskCreationOptions.AttachedToParent);

            t1.Start();
            t2.Start();
            t3.Start();

            //Task[] taskList = { t1, t2, t3 };
            //Task.WaitAll(taskList);

            return results;
        });

        parentTask.Start();

        Task finalTask = parentTask.ContinueWith(parent =>
        {
            foreach (int result in parent.Result)
            {
                Console.WriteLine(result);
            }
        });

        finalTask.Wait();
        Console.ReadLine();
    }

我仍然不明白为什么第一个例子有问题.