CODEWITHSUNDEEP
c#asp.net-coredotnet-httpclientasp.net-core-2.2
Morse
Morse

Reputation: 1572

Net core 2.2: OperationCanceledException instead of TaskCanceledException on HttpClient timeout

In our project we have an HttpClient for outgoing connection with a strict timeout, and previously, I dealt with the timeout situation like all the tutorials suggested: by catching the TaskCanceledException. And it worked. But since recently (can't say the exact time, but about a month), the timeout started to cause the OperationCanceledException.

System.OperationCanceledException: The operation was canceled.
   at System.Net.Http.HttpClient.HandleFinishSendAsyncError(Exception e, CancellationTokenSource cts)
   at System.Net.Http.HttpClient.FinishSendAsyncBuffered(Task`1 sendTask, HttpRequestMessage request, CancellationTokenSource cts, Boolean disposeCts)
   <buisness-logic traceback>
   at Microsoft.AspNetCore.Mvc.Internal.ActionMethodExecutor.TaskOfIActionResultExecutor.Execute(IActionResultTypeMapper mapper, ObjectMethodExecutor executor, Object controller, Object[] arguments)
   at System.Threading.Tasks.ValueTask`1.get_Result()
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.InvokeActionMethodAsync()
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.InvokeNextActionFilterAsync()
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Rethrow(ActionExecutedContext context)
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.InvokeInnerFilterAsync()
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeNextResourceFilter()
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Rethrow(ResourceExecutedContext context)
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeFilterPipelineAsync()
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeAsync()
   at Microsoft.AspNetCore.Routing.EndpointMiddleware.Invoke(HttpContext httpContext)
   at Microsoft.AspNetCore.Routing.EndpointRoutingMiddleware.Invoke(HttpContext httpContext)
   at Microsoft.AspNetCore.Builder.RouterMiddleware.Invoke(HttpContext httpContext)
--- End of stack trace from previous location where exception was thrown ---
   at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware.Invoke(HttpContext context)
   at NSwag.AspNetCore.Middlewares.SwaggerUiIndexMiddleware`1.Invoke(HttpContext context)
   at NSwag.AspNetCore.Middlewares.RedirectToIndexMiddleware.Invoke(HttpContext context)
   at NSwag.AspNetCore.Middlewares.SwaggerDocumentMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Server.IIS.Core.IISHttpContextOfT`1.ProcessRequestAsync()

It's not a big problem to change all the catches to OperationCanceledException, but I'd like to know why? Does anybody know why HttpClient could switch the exception? I deploy the application locally using the VS2019 16.4.3 and IIS express. Net core 2.2

Upvotes: 1

Views: 2841

Answers (1)

Morse
Morse

Reputation: 1572

I found it.

https://github.com/dotnet/corefx/issues/33957

Basically, in case of short timeouts there is a race condition that can cause OCE to happen. What it means is "we do not really know what exactly happen, and we do not care, so you shouldn't too".

Upvotes: 1

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