Timeout error when using redis session

[DSXplor]

I am getting a lot of time out errors after moving our application to redis session state. we usually get either of the following 2 messages:

Timeout performing EVAL (5000ms), next: EVAL, inst: 21, qu: 0, qs: 0, aw: False, bw: SpinningDown, rs: DequeueResult, ws: Idle, in: 0, last-in: 0, cur-in: 54, sync-ops: 579, async-ops: 1, serverEndpoint: xxx.cache.windows.net:6380, conn-sec: 115.79, aoc: 0, mc: 1/1/0, mgr: 9 of 10 available, clientName: wn0sdwk0003PY(SE.Redis-v2.8.0.27420)(Microsoft.Web.RedisSessionStateProvider-v5.1.0.0), IOCP: (Busy=1,Free=999,Min=400,Max=1000), WORKER: (Busy=107,Free=32660,Min=400,Max=32767), v: 2.8.0.27420 (Please take a look at this article for some common client-side issues that can cause timeouts: https://stackexchange.github.io/StackExchange.Redis/Timeouts)

and

Timeout performing EVAL (5000ms), active: EVAL, next: UNKNOWN, inst: 30, qu: 2, qs: 0, aw: True, bw: CheckingForTimeoutComplete, rs: DequeueResult, ws: Writing, in: 0, last-in: 0, cur-in: 20848, sync-ops: 591, async-ops: 1, serverEndpoint: xxx.redis.cache.windows.net:6380, conn-sec: 118.67, aoc: 0, mc: 1/1/0, mgr: 9 of 10 available, clientName: wn0sdwk0003PY(SE.Redis-v2.8.0.27420)(Microsoft.Web.RedisSessionStateProvider-v5.1.0.0), IOCP: (Busy=0,Free=1000,Min=400,Max=1000), WORKER: (Busy=111,Free=32656,Min=400,Max=32767), v: 2.8.0.27420 (Please take a look at this article for some common client-side issues that can cause timeouts: https://stackexchange.github.io/StackExchange.Redis/Timeouts)

and the stack trace:

StackExchange.Redis.RedisTimeoutException: at StackExchange.Redis.ConnectionMultiplexer.ExecuteSyncImpl (StackExchange.Redis, Version=2.0.0.0, Culture=neutral, PublicKeyToken=c219ff1ca8c2ce46) at StackExchange.Redis.RedisDatabase.ScriptEvaluate (StackExchange.Redis, Version=2.0.0.0, Culture=neutral, PublicKeyToken=c219ff1ca8c2ce46) at Microsoft.Web.Redis.StackExchangeClientConnection+<>c__DisplayClass6_0.<Eval>b__0 (Microsoft.Web.RedisSessionStateProvider, Version=5.1.0.0, Culture=neutral, PublicKeyToken=null) at Microsoft.Web.Redis.StackExchangeClientConnection.OperationExecutor (Microsoft.Web.RedisSessionStateProvider, Version=5.1.0.0, Culture=neutral, PublicKeyToken=null) at Microsoft.Web.Redis.StackExchangeClientConnection.RetryLogic (Microsoft.Web.RedisSessionStateProvider, Version=5.1.0.0, Culture=neutral, PublicKeyToken=null) at Microsoft.Web.Redis.StackExchangeClientConnection.Eval (Microsoft.Web.RedisSessionStateProvider, Version=5.1.0.0, Culture=neutral, PublicKeyToken=null) at Microsoft.Web.Redis.RedisConnectionWrapper.TryTakeWriteLockAndGetData (Microsoft.Web.RedisSessionStateProvider, Version=5.1.0.0, Culture=neutral, PublicKeyToken=null) at Microsoft.Web.Redis.RedisSessionStateProvider.GetItemFromSessionStore (Microsoft.Web.RedisSessionStateProvider, Version=5.1.0.0, Culture=neutral, PublicKeyToken=null) at Microsoft.Web.Redis.RedisSessionStateProvider+<GetItemExclusiveAsync>d__19.MoveNext (Microsoft.Web.RedisSessionStateProvider, Version=5.1.0.0, Culture=neutral, PublicKeyToken=null) at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw (mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089) at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd (mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089) at System.Runtime.CompilerServices.TaskAwaiter1.GetResult (mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089) at Microsoft.AspNet.SessionState.SessionStateModuleAsync+<GetSessionStateItemAsync>d__74.MoveNext (Microsoft.AspNet.SessionState.SessionStateModule, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35) at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw (mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089) at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd (mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089) at Microsoft.AspNet.SessionState.SessionStateModuleAsync+<AcquireStateAsync>d__65.MoveNext (Microsoft.AspNet.SessionState.SessionStateModule, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35) at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw (mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089) at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd (mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089) at Microsoft.AspNet.SessionState.TaskAsyncHelper.EndTask (Microsoft.AspNet.SessionState.SessionStateModule, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35) at System.Web.HttpApplication+AsyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute (System.Web, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a) at System.Web.HttpApplication+<>c__DisplayClass285_0.<ExecuteStepImpl>b__0 (System.Web, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a) at System.Web.HttpApplication.ExecuteStepImpl (System.Web, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a) at System.Web.HttpApplication.ExecuteStep (System.Web, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a)

Any ideas on what might be causing these? Thank you

[NickCraver]

The provider here was not awesome in that the extension model for ASP.NET (non-Core) didn't originally envision remote resources, and predates async. I'd definitely recommend if looking at this it be part of an ASP.NET Core (e.g. .NET 8+) move where most of these extension points and new models are async.

Without this, you're seeing WORKER: (Busy=107,Free=32660,Min=400,Max=32767) which indicates thread exhaustion from all the synchronous calls out.

[philon-msft]

If you're able to move the app to ASP.NET Core, you can find more guidance on session state management in ASP.NET Core here: https://learn.microsoft.com/en-us/aspnet/core/fundamentals/app-state?view=aspnetcore-8.0#session-state

[DSXplor]

Thanks for the response, I will add this to the reasons to move to Core.