我有以下简单的控制台应用程序:异步/ AWAIT线程化的好奇心
class Program
{
private static int times = 0;
static void Main(string[] args)
{
Console.WriteLine("Start {0}", Thread.CurrentThread.ManagedThreadId);
var task = DoSomething();
task.Wait();
Console.WriteLine("End {0}", Thread.CurrentThread.ManagedThreadId);
Console.ReadLine();
}
static async Task<bool> DoSomething()
{
times++;
if (times >= 3)
{
return true;
}
Console.WriteLine("DoSomething-1 sleeping {0}", Thread.CurrentThread.ManagedThreadId);
await Task.Run(() =>
{
Console.WriteLine("DoSomething-1 sleep {0}", Thread.CurrentThread.ManagedThreadId);
Task.Yield();
});
Console.WriteLine("DoSomething-1 awake {0}", Thread.CurrentThread.ManagedThreadId);
Console.WriteLine("DoSomething-2 sleeping {0}", Thread.CurrentThread.ManagedThreadId);
await Task.Run(() =>
{
Console.WriteLine("DoSomething-2 sleep {0}", Thread.CurrentThread.ManagedThreadId);
Task.Yield();
});
Console.WriteLine("DoSomething-2 awake {0}", Thread.CurrentThread.ManagedThreadId);
bool b = await DoSomething();
return b;
}
}
与输出
Start 1
DoSomething-1 sleeping 1
DoSomething-1 sleep 3
DoSomething-1 awake 4
DoSomething-2 sleeping 4
DoSomething-2 sleep 4
DoSomething-2 awake 4
DoSomething-1 sleeping 4
DoSomething-1 sleep 3
DoSomething-1 awake 3
DoSomething-2 sleeping 3
DoSomething-2 sleep 3
DoSomething-2 awake 3
End 1
我知道,控制台应用程序不提供这样的SynchronizationContext运行任务在线程池中。但是令我惊讶的是,当从DoSomething
的等待中恢复执行时,我们就和我们在等待中一样。我曾假设,当我们恢复等待方法的执行时,我们会返回到我们等待的线程或完全在另一个线程中。
有谁知道为什么?我的例子有什么缺陷?
我有一个与您的代码示例稍有关联的问题。 Task.Run是否使用System.Threading.ThreadPool或Windows.System.Threading.ThreadPool?如果是后者,并且您的处理程序使用RunAsync方法进行排队,则根据http://msdn.microsoft.com/en-us/library/windowsphone/develop/jj248672.aspx,处理程序不应使用async关键字。那是对的吗。或者,这一切是如何工作的? –
我不确定WinRT实现的细节。但是,我可以肯定地说,将'async' lambda传递给'Task.Run'是安全的。 –