是什么导致 OWIN 管道中的 OperationCanceledException？
What is causing OperationCanceledException in OWIN pipeline?
我在 API 日志中发现了很多 OperationCanceledException。我 认为 它与高负载条件有关，但这可能只是因为在更高负载下调用次数更多，因此异常次数更多。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。对于不同 API 端点的许多调用，它是相同的堆栈跟踪：
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，我的一个 API 服务器在 CPU 用法中展示了我所谓的 "Bart Simpson" 模式。 CPU 会在大约 20-30 秒内达到 95-100% 的范围，然后在 20-30 秒内下降到 5-10%，然后再次回升。这个循环无限期地重复着。因为我们在生产中，所以我没有时间进一步调查，我关闭了那台服务器并让我们的自动缩放规则启动了一个新服务器，然后它运行良好。但我不能保证 Bart Simpson 模式不会影响我们启动的任何其他 API 服务器，而且我不知道是什么原因造成的。
有什么想法吗？
正如所讨论的，在堆栈跟踪中列出的那些自定义中间件之一中的某处，可能混合了 async await 和阻塞调用（ .Result 或 .Wait())，这可能会导致死锁，导致操作挂起、超时和取消。
堆栈跟踪代码段已经提供了可能的嫌疑人列表。
建议首先检查列出的处理请求管道的中间件Invoke。
由于调用堆栈中的代码没有其他错误，这很可能是误报。
如果客户端在服务器响应之前关闭连接，则操作将被取消。
例如，假设您的客户端有一个每 5 秒调用一次的心跳端点，调用耗时 250 毫秒。每次客户端关闭时，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断开连接。 OperationCanceledException 本身不应引起警报。但是，请务必考虑与客户端数量和您的特定应用程序相关的频率。
我在 API 日志中发现了很多 OperationCanceledException。我 认为 它与高负载条件有关，但这可能只是因为在更高负载下调用次数更多，因此异常次数更多。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。对于不同 API 端点的许多调用，它是相同的堆栈跟踪：
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，我的一个 API 服务器在 CPU 用法中展示了我所谓的 "Bart Simpson" 模式。 CPU 会在大约 20-30 秒内达到 95-100% 的范围，然后在 20-30 秒内下降到 5-10%，然后再次回升。这个循环无限期地重复着。因为我们在生产中，所以我没有时间进一步调查，我关闭了那台服务器并让我们的自动缩放规则启动了一个新服务器，然后它运行良好。但我不能保证 Bart Simpson 模式不会影响我们启动的任何其他 API 服务器，而且我不知道是什么原因造成的。
有什么想法吗？
正如所讨论的，在堆栈跟踪中列出的那些自定义中间件之一中的某处，可能混合了 async await 和阻塞调用（ .Result 或 .Wait())，这可能会导致死锁，导致操作挂起、超时和取消。
堆栈跟踪代码段已经提供了可能的嫌疑人列表。
建议首先检查列出的处理请求管道的中间件Invoke。
由于调用堆栈中的代码没有其他错误，这很可能是误报。 如果客户端在服务器响应之前关闭连接，则操作将被取消。 例如，假设您的客户端有一个每 5 秒调用一次的心跳端点，调用耗时 250 毫秒。每次客户端关闭时，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断开连接。 OperationCanceledException 本身不应引起警报。但是，请务必考虑与客户端数量和您的特定应用程序相关的频率。