是什么导致OWIN管道中的OperationCanceledException？

Question

我OperationCanceledException在API日志中发现了很多。我认为这与高负载情况有关，但这可能只是因为在较高的负载下会有更多的调用，因此也有更多的异常。异常的堆栈跟踪没有到达任何控制器代码。它通过我的一些OWIN中间件，但在到达任何控制器之前就死了。而且，对不同API端点的许多调用都是相同的堆栈跟踪：

System.OperationCanceledException: The operation was canceled.
   at System.Threading.CancellationToken.ThrowOperationCanceledException()
   at System.Net.Http.HttpContentExtensions.<ReadAsAsyncCore>d__0`1.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Web.Http.ModelBinding.FormatterParameterBinding.<ExecuteBindingAsyncCore>d__0.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Web.Http.Controllers.HttpActionBinding.<ExecuteBindingAsyncCore>d__0.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Web.Http.Controllers.ActionFilterResult.<ExecuteAsync>d__2.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Web.Http.Filters.AuthorizationFilterAttribute.<ExecuteAuthorizationFilterAsyncCore>d__2.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Web.Http.Dispatcher.HttpControllerDispatcher.<SendAsync>d__1.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at MyDomain.Api.Handlers.ApiCultureHandler.<SendAsync>d__0.MoveNext() in D:\Bamboo\xml-data\build-dir\API-R5V3-JOB1\src\Api\Handlers\ApiCultureHandler.cs:line 50
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Web.Http.HttpServer.<SendAsync>d__0.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Web.Http.Owin.HttpMessageHandlerAdapter.<InvokeCore>d__0.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.Owin.Cors.CorsMiddleware.<Invoke>d__0.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.Owin.Host.SystemWeb.IntegratedPipeline.IntegratedPipelineContextStage.<RunApp>d__5.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.Owin.Security.Infrastructure.AuthenticationMiddleware`1.<Invoke>d__0.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.Owin.Security.Infrastructure.AuthenticationMiddleware`1.<Invoke>d__0.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at DependencyResolution.Api.Middleware.AuditLogMiddleware.<Invoke>d__1.MoveNext() in D:\Bamboo\xml-data\build-dir\API-R5V3-JOB1\src\DependencyResolution\Api\Middleware\AuditLogMiddleware.cs:line 23
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at DependencyResolution.Api.Middleware.ShardingMiddleware.<Invoke>d__2.MoveNext() in D:\Bamboo\xml-data\build-dir\API-R5V3-JOB1\src\DependencyResolution\Api\Middleware\ShardingMiddleware.cs:line 77
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at DependencyResolution.Api.Middleware.StructureMapMiddleware.<Invoke>d__2.MoveNext() in D:\Bamboo\xml-data\build-dir\API-R5V3-JOB1\src\DependencyResolution\Api\Middleware\StructureMapMiddleware.cs:line 29
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at DependencyResolution.Api.Middleware.ExceptionHandlerMiddleware.<Invoke>d__3.MoveNext() in D:\Bamboo\xml-data\build-dir\API-R5V3-JOB1\src\DependencyResolution\Api\Middleware\ExceptionHandlerMiddleware.cs:line 33

这非常令人不安，因为我不确定如何调试它。

其他可能有用的信息：在发生这些错误时，我的一台API服务器在CPU使用率方面表现出我所说的“ Bart Simpson”模式。CPU会在大约20-30秒的时间内达到95-100％的范围，然后再下降20-30秒降至5-10％，然后再次备份。循环无限重复。因为我们正在生产中，所以我没有时间进行进一步的调查，我杀死了该服务器，并让我们的自动缩放规则启动了一个新服务器，然后该服务器运行良好。但是我不能保证Bart Simpson模式不会影响我们提出的任何其他API服务器，而且我也不知道可能会导致它。

有任何想法吗？

Answer 1

正如所讨论的，在堆栈跟踪中列出的自定义中间件之一中的某个地方，可能存在异步等待和阻塞调用（.Result或.Wait()）的混合，这可能会导致死锁，从而导致操作挂起、超时和取消。

堆栈跟踪片段已经提供了可能的嫌疑人列表。

建议首先检查Invoke列出的处理请求管道的中间件。

Answer 2

由于调用堆栈中的代码中没有其他错误，因此这很可能是错误警报。如果客户端在服务器响应之前关闭了连接，则该操作将被取消。例如，假设您的客户端有一个心跳端点，它每5秒调用一次，呼叫耗时250毫秒。每次客户关闭时，都有5％的机会取消操作。在许多正常情况下，客户端可能会在收到响应之前切断连接。OperationCanceledException本身不应该引起警报。但是，一定要考虑与客户数量和您的特定应用程序有关的频率。