Question

我有Task，Task1和Task2。 Task1和Task2彼此独立，但都取决于Task的结果。我可以这样做：

static async Task Test1()
{
    var task = Task.Delay(1000);

    var task1 = task.ContinueWith(_ => 
    {
        Console.WriteLine("Task1, thread: {0}", Thread.CurrentThread.ManagedThreadId);
    });

    var task2 = task.ContinueWith(_ =>
    {
        Console.WriteLine("Task2, thread: {0}", Thread.CurrentThread.ManagedThreadId);
    });

    await Task.WhenAll(task1, task2);
}

或者，或者，这样：

static async Task Test2()
{
    var task = Task.Delay(1000);
    await task;

    var task1 = Task.Run(() =>
    {
        Console.WriteLine("Task1, thread: {0}", Thread.CurrentThread.ManagedThreadId);
    });

    var task2 = Task.Run(() =>
    {
        Console.WriteLine("Task2, thread: {0}", Thread.CurrentThread.ManagedThreadId);
    });

    await Task.WhenAll(task1, task2);
}

我更喜欢哪种方式？它们都同样有效吗？有没有更好的方法来组成这个？

Answer 1

我认为更好的方法是为后续async创建单独的Task方法。类似的东西：

private static async Task Task1(Task task)
{
    await task;
    Console.WriteLine("Task1, thread: {0}", Thread.CurrentThread.ManagedThreadId);
}

private static async Task Task2(Task task)
{
    await task;
    Console.WriteLine("Task2, thread: {0}", Thread.CurrentThread.ManagedThreadId);
}

private static async Task Test1()
{
    var task = Task.Delay(1000);

    var task1 = Task1(task);
    var task2 = Task2(task);

    await Task.WhenAll(task1, task2);
}

对于同步上下文（如果存在），这将与您的代码的行为不同，但您可以使用await task.ConfigureAwait(false)来影响它。

Answer 2

这真的不是一个答案，只是另一种选择

var task = Task.Delay(1000);
await task.ContinueWith(_ =>
    {
        Parallel.Invoke(
            () => {
                Console.WriteLine("Task1, thread: {0}",Thread.CurrentThread.ManagedThreadId);
            },
            () => {
                Console.WriteLine("Task2, thread: {0}", Thread.CurrentThread.ManagedThreadId);
            });
    });

Y风格的任务执行

2 个答案: