c# - HyperV 环境中 AsyncController 的 TimeoutException

Question

我们在 Beta HyperV 环境中的 MVC AsyncController 上收到 TimeoutException。在本地调试时一切正常，但是当我们部署到预生产环境时，我们得到这个错误:

[TimeoutException: 操作超时。] System.Web.Mvc.Async.WrappedAsyncResult`1.End() +129 System.Web.Mvc.Async.<>c_DisplayClass39.b_38(IAsyncResult asyncResult) +23 System.Web.Mvc.Async.<>c_DisplayClass33.b_2d() +125 System.Web.Mvc.Async.<>c_DisplayClass49.b_43() +452 System.Web.Mvc.Async.<>c_DisplayClass49.b_43() +452 System.Web.Mvc.Async.<>c_DisplayClass49.b_43() +452 System.Web.Mvc.Async.<>c_DisplayClass31.b_30(IAsyncResult asyncResult) +15 System.Web.Mvc.Async.<>c_DisplayClass24.b_1a() +31 System.Web.Mvc.Async.<>c_DisplayClass1f.b_1c(IAsyncResult asyncResult) +230 System.Web.Mvc.<>c_DisplayClass17.b_12(IAsyncResult asyncResult) +28 System.Web.Mvc.Async.<>c_DisplayClass4.b_3(IAsyncResult ar) +20 System.Web.Mvc.AsyncController.EndExecuteCore(IAsyncResult asyncResult) +53 System.Web.Mvc.Async.<>c_DisplayClass4.b_3(IAsyncResult ar) +20 System.Web.Mvc.<>c_DisplayClass8.b_3(IAsyncResult asyncResult) +42 System.Web.Mvc.Async.<>c_DisplayClass4.b_3(IAsyncResult ar) +20 System.Web.CallHandlerExecutionStep.OnAsyncHandlerCompletion(IAsyncResult ar) +136

    [OutputCache(Duration = 0, NoStore = true, VaryByParam = "")]
            public void IndexAsync()
            {
                using (var context = Repository.CreateContext().CreateUnitOfWork())
                {
                    user = context.Users.Single(u => u.Username == User.Identity.Name);

                        AsyncManager.OutstandingOperations.Increment();

                        ThreadPool.QueueUserWorkItem(o => {
                            var sync = myService.DoThingsAsync(user);
                            sync.AsyncWaitHandle.WaitOne();
                            AsyncManager.OutstandingOperations.Decrement();  
                        });
                }
            }

/// IndexCompleted is never called
     public ActionResult IndexCompleted(string property)
            {
                using (var context = Repository.CreateContext().CreateUnitOfWork())
                {
                    var user = context.Users.Single(u => u.Username == User.Identity.Name);

                    var model = new MyViewModel
                    {
                        ModelProperty = user.Property
                    };

                    return View("Index", model);
                }
            }

此错误的一些可能原因是什么？

Answer 1

这是当异步操作花费的时间超过配置的 AsyncTimeout 值(默认为 45 秒)时抛出的异常。您可以通过使用 AsyncTimeout 属性修饰 ActionMethod 来显式控制此值。例如，将异步超时设置为一整分钟:

[AsyncTimeout(60000)]
public void IndexAsync()
{
   ...
}

您也可以使用 NoAsyncTimeout 属性，但您很容易受到异步操作永远不会完成并使您的 Web 请求陷入困境的影响。