c#Delegate.BeginInvoke()和线程ID

Question

假设我们有一些像这样的简单代码:

private static void Main()
{
    Console.WriteLine("Main thread {0}\n", Thread.CurrentThread.ManagedThreadId);

    Action asyncCaller1 = () => LongPerfomingTask(5);
    Action asyncCaller2 = () => LongPerfomingTask(3);

    var asyncResult1 = asyncCaller1.BeginInvoke(null, null);
    var asyncResult2 = asyncCaller2.BeginInvoke(null, null);

    asyncResult1.AsyncWaitHandle.WaitOne();
    asyncResult2.AsyncWaitHandle.WaitOne();

    Console.WriteLine("Done");
}

private static void LongPerfomringTask(int seconds)
{
    Thread.Sleep(TimeSpan.FromSeconds(seconds));

    Console.WriteLine("Thread {0} finished execution", Thread.CurrentThread.ManagedThreadId);
}

Delegate.BeginInvoke()不会创建一个线程,它在调用者的线程中处于空闲状态时执行代码,对吧？那么,为什么这个示例应用程序的输出是这样的:

Main thread 1

Thread 4 finished execution
Thread 3 finished execution
Done

Answer 1

不,Delegate.BeginInvoke使用线程池.总是.没有"在闲置时在调用者的线程中执行"的概念,除非您考虑将任务添加到UI消息队列中......您是否与Control.BeginInvoke/ Dispatcher.BeginInvoke？

在这种情况下,你有一个控制台应用程序 - 开始时没有消息.