問題描述
部署.NET 應用到App Service中，應用中呼叫Storage Account的SDK上傳檔案到Blob中。只是比較高頻率在UploadAsync方法中遇見：OutOfMemoryException
異常資訊
ERROR Microsoft.AspNetCore.Server.Kestrel.? [?] - MESSAGE: Connection id "0HN3UB91BK6BS", Request id "0HN3UB91BK6BS:00000585": An unhandled exception was thrown by the application.
System.OutOfMemoryException: Exception of type 'System.OutOfMemoryException' was thrown.
at System.GC.AllocateNewArray(IntPtr typeHandle, Int32 length, GC_ALLOC_FLAGS flags)
at System.GC.<AllocateUninitializedArray>g__AllocateNewUninitializedArray|66_0[T](Int32 length, Boolean pinned)
at System.Buffers.TlsOverPerCoreLockedStacksArrayPool`1.Rent(Int32 minimumLength)
at Microsoft.AspNetCore.WebUtilities.HttpResponseStreamWriter..ctor(Stream stream, Encoding encoding, Int32 bufferSize, ArrayPool`1 bytePool, ArrayPool`1 charPool)
at Microsoft.AspNetCore.Mvc.Infrastructure.MemoryPoolHttpResponseStreamWriterFactory.CreateWriter(Stream stream, Encoding encoding)
at Microsoft.AspNetCore.Mvc.NewtonsoftJson.NewtonsoftJsonResultExecutor.ExecuteAsync(ActionContext context, JsonResult result)
at Microsoft.AspNetCore.Mvc.NewtonsoftJson.NewtonsoftJsonResultExecutor.ExecuteAsync(ActionContext context, JsonResult result)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeNextResultFilterAsync>g__Awaited|30_0[TFilter,TFilterAsync](ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResultExecutedContextSealed context)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.ResultNext[TFilter,TFilterAsync](State& next, Scope& scope, Object& state, Boolean& isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.InvokeResultFilters()
--- End of stack trace from previous location ---
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeFilterPipelineAsync>g__Awaited|20_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
at Microsoft.AspNetCore.Routing.EndpointMiddleware.<Invoke>g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)
at Microsoft.AspNetCore.Authorization.Policy.AuthorizationMiddlewareResultHandler.HandleAsync(RequestDelegate next, HttpContext context, AuthorizationPolicy policy, PolicyAuthorizationResult authorizeResult)
at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke(HttpContext context)
at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.HttpProtocol.ProcessRequests[TContext](IHttpApplication`1 application)
問題解答
從Exception中的Stack Trace上看Out Of Memory發生在GC Allocate New Array, 是在HTTP Process Requests/Response時，需要申請記憶體遇見記憶體不足異常。 而異常中資訊不充足無法定位。但從App Service的角度，可以考慮修改App Service Platform為64bit (App Service for windows 預設為32bit)。如修改後，依舊出現OutOfMemory異常，則需要考慮收集w3wp.exe 或 dotnet.exe 程序的DUMP檔案進行深入分析。
I see the message "Worker Process requested recycle due to 'Percent Memory' limit." How do I address this issue?
The maximum available amount of memory for a 32-bit process (even on a 64-bit operating system) is 2 GB. By default, the worker process is set to 32-bit in App Service (for compatibility with legacy web applications).
Consider switching to 64-bit processes so you can take advantage of the additional memory available in your Web Worker role. This action triggers a web app restart, so schedule accordingly.
Also note that a 64-bit environment requires a Basic or Standard service plan. Free and Shared plans always run in a 32-bit environment.
For more information, see Configure web apps in App Service.
analyzing the memory dump
This article provides guidance about Microsoft Azure App Service debugging features for capturing memory dumps. The capture method that you use is dictated by the scenario in which you capture a memory dump for troubleshooting a performance or availability issue. For example, capturing a memory dump is different for a process that's experiencing excessive memory consumption than for a process that's throwing exceptions or responding slowly. The process in this context is the Internet Information Services (IIS) worker process (W3WP, which runs as w3wp.exe).
參考資料
Capture memory dumps on the Azure App Service platform ： https://learn.microsoft.com/en-us/troubleshoot/azure/app-service/capture-memory-dumps-app-service#next-steps-analyzing-the-memory-dump
Application performance FAQs for Web Apps in Azure : https://learn.microsoft.com/en-us/troubleshoot/azure/app-service/web-apps-performance-faqs