问题
We have a ASP.NET MVC4 application which uses Entity Framework 4.0. When we deploy on the production server, the CPU rises after some time (~2-5h) until nearly 100%. The memory also rises then until maximum. After a while the application pool will be resetted automatically because of the high memory.
Server: Windows 2008 R2 Standard SP1 IIS: 7 (V 7.5.7600.16385) Only one application pool and one webapplication is running.
Stacktrace from Debug Diagnostic Tool of the thread which consumes most of the CPU:
SNIReadSyncOverAsync(SNI_ConnWrapper*, SNI_Packet**, Int32)
.SNIReadSyncOverAsync(SNI_ConnWrapper*, SNI_Packet**, Int32)
System.Web.Hosting.UnsafeIISMethods.MgdIndicateCompletion(IntPtr, System.Web.RequestNotificationStatus ByRef)
System.Web.Hosting.UnsafeIISMethods.MgdIndicateCompletion(IntPtr, System.Web.RequestNotificationStatus ByRef)
ntdll!NtWaitForSingleObject
KERNELBASE!WaitForSingleObjectEx
System_Data!SNIReadSyncOverAsync
System_Data_ni!load_config_used
System_Data_ni!load_config_used
System_Data_ni!load_config_used
System_Data_ni!load_config_used
System_Data_ni!load_config_used
System_Data_ni!load_config_used
System_Data_ni!load_config_used
System_Data_ni!load_config_used
System_Data_ni!load_config_used
System_Data_ni!load_config_used
System_Data_ni!load_config_used
System_Data_ni!load_config_used
System_Data_ni!load_config_used
System_Data_ni!load_config_used
System_Data_ni!load_config_used
System_Data_Entity_ni
System_Data_Entity_ni
System_Data_Entity_ni
System_Data_Entity_ni
System_Core_ni
System_Core_ni
0x000007fe`99223112
0x000007fe`99222a88
0x000007fe`99222899
0x000007fe`992205cb
0x000007fe`99355596
System_Web_Mvc_ni+138058
System_Web_Mvc_ni+13ca67
System_Web_Mvc_ni+13e71c
System_Web_Mvc_ni+13ca03
System_Web_Mvc_ni+13d175
System_Web_Mvc_ni+13cbe9
System_Web_Mvc_ni+1431df
System_Web_Mvc_ni+13dade
System_Web_Mvc_ni+14f5fe
System_Web_Mvc_ni+13b0ef
System_Web_Mvc_ni+14f514
System_Web_ni
System_Web_ni
System_Web_ni
System_Web_ni
System_Web_ni
System_Web_ni
System_Web_ni
System_Web_ni
clr!UMThunkStub
webengine4!W3_MGD_HANDLER::ProcessNotification
webengine4!W3_MGD_HANDLER::DoWork
webengine4!RequestDoWork
webengine4!CMgdEngHttpModule::OnExecuteRequestHandler
iiscore!NOTIFICATION_CONTEXT::RequestDoWork
iiscore!NOTIFICATION_CONTEXT::CallModulesInternal
iiscore!NOTIFICATION_CONTEXT::CallModules
iiscore!W3_CONTEXT::DoWork
iiscore!W3_CONTEXT::IndicateCompletion
webengine4!MgdIndicateCompletion
System_Web_ni
System_Web_ni
System_Web_ni
System_Web_ni
clr!UM2MThunk_WrapperHelper
clr!UM2MThunk_Wrapper
clr!Thread::DoADCallBack
clr!UM2MDoADCallBack
clr!UMThunkStub
webengine4!W3_MGD_HANDLER::ProcessNotification
webengine4!ProcessNotificationCallback
clr!UnManagedPerAppDomainTPCount::DispatchWorkItem
clr!ThreadpoolMgr::ExecuteWorkRequest
clr!ThreadpoolMgr::WorkerThreadStart
clr!Thread::intermediateThreadProc
kernel32!BaseThreadInitThunk
ntdll!RtlUserThreadStart
Have you an idea what is the reason of this CPU rising?
回答1:
Hey I had the exact same issue with SNIReadSyncOverAsync using a significant amount of thread time (I discovered this using DebugDiag).
I don't know if this will help anyone else but it looks like our problem was with the Azure DB server we were using. We had it set to only 50 DTUs, which has a maximum of 100 concurrent requests.
Basically SNIReadSyncOverAsync is so large because the web server has to sit there waiting for a response from the DB server, and the DB server can only handle 100 requests at a time so the web server ends up waiting for a long time (resulting in a 100% CPU usage and an inaccessible website). This can pop up with a recent increase in web traffic (e.g.: if you guys recently bought advertisements and saw your web traffic go up by a large percentage, now the 100 concurrent requests aren't enough)
So if you're like us and you're using Azure DB, check your DTU % usage. If its really high often (80-90%, etc.) try increasing it to double or even quadruple (this can be expensive!). We went from "Elastic Standard" (50 eDTUs) to "Standard S4" (400 DTUs) and we've yet to see the CPU usage hit 100%. In fact its been floating at around 7-9% since.
来源：https://stackoverflow.com/questions/14609129/cpu-usage-of-w3wp-rises-to-100-on-a-asp-net-mvc4-web-application