System.Web.Mvc.FilterProviderCollection.GetFilters 处的 NullReferenceException

Question

我有一个在 Windows 2008 R2 (IIS 7.5) 上运行的 MVC 5 应用程序 (.NET 4.5.1)

在运行负载测试时，会定期抛出以下异常。不幸的是，我无法在本地复制并且相当卡住，所以希望社区可能有更多的想法。 （更新：现在已经能够在负载下重现）

查看 FilterProviderCollection.GetFilters 的来源表明它可能是依赖解析器 - 但没有更多信息，我不愿意简单地替换库。目前它使用 SimpleInjector。

如果是这种情况，我猜它是由应用程序池回收引起的，但无法证实这一点（启用记录应用程序池中回收的所有原因对我没有任何用处）

经过大量搜索，我确实找到了一些可能是 Glimpse 的参考。我已经确认不是这种情况。我还剥离并重建了该项目，以帮助获得信心，这不仅仅是 nuget-package 升级的怪异之处。

任何关于可能导致它的原因的建议，或者我可以如何添加额外的日志记录以获取更多信息，我们将不胜感激。谢谢。

Exception information: 
    Exception type: NullReferenceException 
    Exception message: Object reference not set to an instance of an object.
   at System.Web.Mvc.FilterProviderCollection.GetFilters(ControllerContext controllerContext, ActionDescriptor actionDescriptor)
   at System.Web.Mvc.ControllerActionInvoker.GetFilters(ControllerContext controllerContext, ActionDescriptor actionDescriptor)
   at System.Web.Mvc.Async.AsyncControllerActionInvoker.BeginInvokeAction(ControllerContext controllerContext, String actionName, AsyncCallback callback, Object state)
   at System.Web.Mvc.Controller.<BeginExecuteCore>b__1c(AsyncCallback asyncCallback, Object asyncState, ExecuteCoreState innerState)
   at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncVoid`1.CallBeginDelegate(AsyncCallback callback, Object callbackState)
   at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResultBase`1.Begin(AsyncCallback callback, Object state, Int32 timeout)
   at System.Web.Mvc.Async.AsyncResultWrapper.Begin[TState](AsyncCallback callback, Object callbackState, BeginInvokeDelegate`1 beginDelegate, EndInvokeVoidDelegate`1 endDelegate, TState invokeState, Object tag, Int32 timeout, SynchronizationContext callbackSyncContext)
   at System.Web.Mvc.Controller.BeginExecuteCore(AsyncCallback callback, Object state)
   at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResultBase`1.Begin(AsyncCallback callback, Object state, Int32 timeout)
   at System.Web.Mvc.Async.AsyncResultWrapper.Begin[TState](AsyncCallback callback, Object callbackState, BeginInvokeDelegate`1 beginDelegate, EndInvokeVoidDelegate`1 endDelegate, TState invokeState, Object tag, Int32 timeout, SynchronizationContext callbackSyncContext)
   at System.Web.Mvc.Controller.BeginExecute(RequestContext requestContext, AsyncCallback callback, Object state)
   at System.Web.Mvc.MvcHandler.<BeginProcessRequest>b__4(AsyncCallback asyncCallback, Object asyncState, ProcessRequestState innerState)
   at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncVoid`1.CallBeginDelegate(AsyncCallback callback, Object callbackState)
   at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResultBase`1.Begin(AsyncCallback callback, Object state, Int32 timeout)
   at System.Web.Mvc.Async.AsyncResultWrapper.Begin[TState](AsyncCallback callback, Object callbackState, BeginInvokeDelegate`1 beginDelegate, EndInvokeVoidDelegate`1 endDelegate, TState invokeState, Object tag, Int32 timeout, SynchronizationContext callbackSyncContext)
   at System.Web.Mvc.MvcHandler.BeginProcessRequest(HttpContextBase httpContext, AsyncCallback callback, Object state)
   at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
   at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)

更新 1

我已经找到了在测试环境中复制的方法：

1. 在应用程序上施加恒定负载（最少 20 个虚拟用户）
2. 手动回收应用程序池（重复直到触发失败）

在没有负载的情况下回收应用程序池似乎不会触发失败。

更令人担忧的是，将“禁用重叠回收”设置为 True 并不能阻止它们发生。我原以为这会停止任何回收问题，因为它会在启动新进程之前完全破坏工作进程。

更新 2

Global.asax 和相关配置看起来（对我来说）与默认模板相差不远。看看你的想法？

    public class MyHttpApplication : HttpApplication {

            public MyHttpApplication() {
                    SimpleInjectorConfig.InitializeContainer(); //seems to need to be in ctor to support HttpModule dependencies
            }

            protected void Application_Start() {
                    MvcHandler.DisableMvcResponseHeader = true;

                    AreaRegistration.RegisterAllAreas();

                    ViewEngineConfig.RegisterViewEngines(ViewEngines.Engines);
                    WebApiConfig.Register(GlobalConfiguration.Configuration);
                    FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
                    RouteConfig.RegisterRoutes(RouteTable.Routes);
                    BinderConfig.RegisterGlobalBinders(ModelBinders.Binders);
            }

各种 XxxConfig 类几乎不在模板中。

    public static class FilterConfig {
            public static void RegisterGlobalFilters(GlobalFilterCollection filters) {
                    filters.Add(new AuthorizeAttribute());
            }
    }

    public static class SimpleInjectorConfig {
            /// <summary>Initialize the container and register it as MVC Dependency Resolver.</summary>
            public static void InitializeContainer() {
                    var container = new Container();
                    container.Options.AllowResolvingFuncFactories();

                    RegisterServices(container);

                    container.RegisterMvcControllers(Assembly.GetExecutingAssembly());
                    container.RegisterMvcIntegratedFilterProvider();
                    container.RegisterWebApiControllers(GlobalConfiguration.Configuration);

                    //container.Verify(); //see http://bit.ly/YE8OJj for more info

                    DependencyResolver.SetResolver(new SimpleInjectorDependencyResolver(container));
                    GlobalConfiguration.Configuration.DependencyResolver = new SimpleInjectorWebApiDependencyResolver(container);
            }

更新 3

在关闭重叠回收的情况下运行时，我能够获得以下变体堆栈跟踪。

[IndexOutOfRangeException: Index was outside the bounds of the array.]
   System.Collections.Generic.Enumerator.MoveNext() +112
   System.Linq.<ConcatIterator>d__71`1.MoveNext() +643
   System.Linq.Buffer`1..ctor(IEnumerable`1 source) +520
   System.Linq.Enumerable.ToArray(IEnumerable`1 source) +103
   System.Web.Mvc.FilterProviderCollection.GetFilters(ControllerContext controllerContext, ActionDescriptor actionDescriptor) +89
   System.Web.Mvc.ControllerActionInvoker.GetFilters(ControllerContext controllerContext, ActionDescriptor actionDescriptor) +38
   System.Web.Mvc.Async.AsyncControllerActionInvoker.BeginInvokeAction(ControllerContext controllerContext, String actionName, AsyncCallback callback, Object state) +333
   System.Web.Mvc.Controller.<BeginExecuteCore>b__1c(AsyncCallback asyncCallback, Object asyncState, ExecuteCoreState innerState) +45
   System.Web.Mvc.Async.WrappedAsyncVoid`1.CallBeginDelegate(AsyncCallback callback, Object callbackState) +111
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.Begin(AsyncCallback callback, Object state, Int32 timeout) +150
   System.Web.Mvc.Async.AsyncResultWrapper.Begin(AsyncCallback callback, Object callbackState, BeginInvokeDelegate`1 beginDelegate, EndInvokeVoidDelegate`1 endDelegate, TState invokeState, Object tag, Int32 timeout, SynchronizationContext callbackSyncContext) +203
   System.Web.Mvc.Controller.BeginExecuteCore(AsyncCallback callback, Object state) +879
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.Begin(AsyncCallback callback, Object state, Int32 timeout) +150
   System.Web.Mvc.Async.AsyncResultWrapper.Begin(AsyncCallback callback, Object callbackState, BeginInvokeDelegate`1 beginDelegate, EndInvokeVoidDelegate`1 endDelegate, TState invokeState, Object tag, Int32 timeout, SynchronizationContext callbackSyncContext) +154
   System.Web.Mvc.Controller.BeginExecute(RequestContext requestContext, AsyncCallback callback, Object state) +527
   System.Web.Mvc.MvcHandler.<BeginProcessRequest>b__4(AsyncCallback asyncCallback, Object asyncState, ProcessRequestState innerState) +108
   System.Web.Mvc.Async.WrappedAsyncVoid`1.CallBeginDelegate(AsyncCallback callback, Object callbackState) +111
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.Begin(AsyncCallback callback, Object state, Int32 timeout) +150
   System.Web.Mvc.Async.AsyncResultWrapper.Begin(AsyncCallback callback, Object callbackState, BeginInvokeDelegate`1 beginDelegate, EndInvokeVoidDelegate`1 endDelegate, TState invokeState, Object tag, Int32 timeout, SynchronizationContext callbackSyncContext) +203
   System.Web.Mvc.MvcHandler.BeginProcessRequest(HttpContextBase httpContext, AsyncCallback callback, Object state) +665
   System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +12638163
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +288

和

[IndexOutOfRangeException: Index was outside the bounds of the array.]
   System.Collections.Generic.Enumerator.MoveNext() +112
   System.Linq.<OfTypeIterator>d__aa`1.MoveNext() +344
   System.Collections.Generic.List`1..ctor(IEnumerable`1 collection) +536
   System.Linq.Enumerable.ToList(IEnumerable`1 source) +80
   SimpleInjector.SimpleInjectorMvcExtensions.RegisterMvcIntegratedFilterProvider(Container container) +271
   WebProject.SimpleInjectorConfig.InitializeContainer() in c:\...\App_Start\SimpleInjectorConfig.cs:35
   WebProject.MyHttpApplication..ctor() in c:\...\Global.asax.cs:14
   ASP.global_asax..ctor() in c:\...\App_global.asax.3szzcx02.0.cs:0

[TargetInvocationException: Exception has been thrown by the target of an invocation.]
   System.RuntimeTypeHandle.CreateInstance(RuntimeType type, Boolean publicOnly, Boolean noCheck, Boolean& canBeCached, RuntimeMethodHandleInternal& ctor, Boolean& bNeedSecurityCheck) +0
   System.RuntimeType.CreateInstanceSlow(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache, StackCrawlMark& stackMark) +159
   System.RuntimeType.CreateInstanceDefaultCtor(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache, StackCrawlMark& stackMark) +256
   System.Activator.CreateInstance(Type type, Boolean nonPublic) +127
   System.RuntimeType.CreateInstanceImpl(BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture, Object[] activationAttributes, StackCrawlMark& stackMark) +14259433
   System.Activator.CreateInstance(Type type, BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture, Object[] activationAttributes) +200
   System.Activator.CreateInstance(Type type, BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture) +28
   System.Web.HttpRuntime.CreateNonPublicInstance(Type type, Object[] args) +83
   System.Web.HttpApplicationFactory.GetNormalApplicationInstance(HttpContext context) +246
   System.Web.HttpApplicationFactory.GetApplicationInstance(HttpContext context) +178
   System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) +333

Answer 1

下面这行给你带来了麻烦：

public MyHttpApplication() {
    SimpleInjectorConfig.InitializeContainer(); //seems to need to be in c...    
}

MyHttpApplication 可以被多次调用，这会导致创建多个容器，每个容器都尝试使用RegisterMvcIntegratedFilterProvider 将自己注册为过滤器提供程序。您应该确保只为该应用程序域创建一个容器实例，因此您只需调用一次RegisterMvcIntegratedFilterProvider。

Answer 2

首先，感谢Steven 帮助分析问题。

原来问题是由于 SimpleInjectorConfig.InitializeContainer 的无害放置造成的。

虽然 ASP.NET 运行时确保 Application_Start 只会被调用一次，但它可以创建多个 HttpApplications。在 ctor 中调用意味着应该运行一次的初始化最终在负载下被回收时被调用了很多次。

public MyHttpApplication() {
  SimpleInjectorConfig.InitializeContainer(); //WRONG
}

将其移至 Application_Start 可解决眼前的问题。

protected void Application_Start() {
  SimpleInjectorConfig.InitializeContainer();
}

鉴于仅在 Ctor 中调用了 IHttpModule 支持，我还进一步将依赖项注入到 IHttpModule 中。 HttpModuleMagic 很适合这个。