Code Blocking call but I don't know why

[ignaciosalazarcalle]

Hello,

I'm executing this code's line:

return await Cache.GetOrCreateAsync(CacheApis.GetEntity(UrlApis.GetTemasPisos, filter),
                async entry =>
                {
                    return await _context.TemasPisos.AsNoTracking()
                        .Where(x =>
                            x.NuSerial.Equals(filter.NuSerial) &&
                            x.Dni.Equals(filter.Dni))
                        .Select(x => new Enumerado
                        {
                            Id = x.TemaId.ToString(),
                            Descripcion = x.DescripcionTema
                        })
                        .ToListAsync();
                });

And I always receive the same error:

[TemasPisosController.GetTemasPisos] Ben.Diagnostics.BlockingMonitor:Blocking method has been invoked and blocked, this can lead to threadpool starvation.
"at System.Threading.WaitHandle.WaitOne(Int32 millisecondsTimeout)\r\n  
at Microsoft.Data.SqlClient.TdsParser.CheckResetConnection(TdsParserStateObject stateObj)\r\n   
at Microsoft.Data.SqlClient.TdsParserStateObject.WritePacket(Byte flushMode, Boolean canAccumulate)\r\n   
at Microsoft.Data.SqlClient.TdsParserStateObject.ExecuteFlush()\r\n   
at Microsoft.Data.SqlClient.TdsParser.TdsExecuteRPC(SqlCommand cmd, _SqlRPC[] rpcArray, Int32 timeout, Boolean inSchema, SqlNotificationRequest notificationRequest, TdsParserStateObject stateObj, Boolean isCommandProc, Boolean sync, TaskCompletionSource`1 completion, Int32 startRpc, Int32 startParam)\r\n   
at Microsoft.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean isAsync, Int32 timeout, Task& task, Boolean asyncWrite, Boolean inRetry, SqlDataReader ds, Boolean describeParameterEncryptionRequest)\r\n   
at Microsoft.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, TaskCompletionSource`1 completion, Int32 timeout, Task& task, Boolean& usedCache, Boolean asyncWrite, Boolean inRetry, String method)\r\n   
at Microsoft.Data.SqlClient.SqlCommand.BeginExecuteReaderInternal(CommandBehavior behavior, AsyncCallback callback, Object stateObject, Int32 timeout, Boolean inRetry, Boolean asyncWrite)\r\n   
at Microsoft.Data.SqlClient.SqlCommand.BeginExecuteReaderAsync(CommandBehavior behavior, AsyncCallback callback, Object stateObject)\r\n   
at Microsoft.Data.SqlClient.SqlCommand.<>c__DisplayClass168_0.<ExecuteReaderAsync>b__1(CommandBehavior commandBehavior, AsyncCallback callback, Object stateObject)\r\n   
at System.Threading.Tasks.TaskFactory`1.FromAsyncImpl[TArg1](Func`4 beginMethod, Func`2 endFunction, Action`1 endAction, TArg1 arg1, Object state, TaskCreationOptions creationOptions)\r\n   
at System.Threading.Tasks.TaskFactory`1.FromAsync[TArg1](Func`4 beginMethod, Func`2 endMethod, TArg1 arg1, Object state)\r\n   
at Microsoft.Data.SqlClient.SqlCommand.ExecuteReaderAsync(CommandBehavior behavior, CancellationToken cancellationToken)\r\n   
at Microsoft.Data.SqlClient.SqlCommand.ExecuteDbDataReaderAsync(CommandBehavior behavior, CancellationToken cancellationToken)\r\n   
at System.Data.Common.DbCommand.ExecuteReaderAsync(CancellationToken cancellationToken)\r\n   
at Microsoft.EntityFrameworkCore.Storage.RelationalCommand.ExecuteReaderAsync(RelationalCommandParameterObject parameterObject, CancellationToken cancellationToken)\r\n   
at System.Runtime.CompilerServices.AsyncMethodBuilderCore.Start[TStateMachine](TStateMachine& stateMachine)\r\n   
at Microsoft.EntityFrameworkCore.Storage.RelationalCommand.ExecuteReaderAsync(RelationalCommandParameterObject parameterObject, CancellationToken cancellationToken)\r\n   
at Microsoft.EntityFrameworkCore.Query.Internal.QueryingEnumerable`1.AsyncEnumerator.InitializeReaderAsync(DbContext _, Boolean result, CancellationToken cancellationToken)\r\n   
at System.Runtime.CompilerServices.AsyncMethodBuilderCore.Start[TStateMachine](TStateMachine& stateMachine)\r\n   
at Microsoft.EntityFrameworkCore.Query.Internal.QueryingEnumerable`1.AsyncEnumerator.InitializeReaderAsync(DbContext _, Boolean result, CancellationToken cancellationToken)\r\n   
at Microsoft.EntityFrameworkCore.SqlServer.Storage.Internal.SqlServerExecutionStrategy.ExecuteAsync[TState,TResult](TState state, Func`4 operation, Func`4 verifySucceeded, CancellationToken cancellationToken)\r\n   
at System.Runtime.CompilerServices.AsyncMethodBuilderCore.Start[TStateMachine](TStateMachine& stateMachine)\r\n   
at Microsoft.EntityFrameworkCore.SqlServer.Storage.Internal.SqlServerExecutionStrategy.ExecuteAsync[TState,TResult](TState state, Func`4 operation, Func`4 verifySucceeded, CancellationToken cancellationToken)\r\n   
at Microsoft.EntityFrameworkCore.Query.Internal.QueryingEnumerable`1.AsyncEnumerator.MoveNextAsync()\r\n   
at System.Runtime.CompilerServices.AsyncMethodBuilderCore.Start[TStateMachine](TStateMachine& stateMachine)\r\n   
at Microsoft.EntityFrameworkCore.Query.Internal.QueryingEnumerable`1.AsyncEnumerator.MoveNextAsync()\r\n   
at System.Runtime.CompilerServices.ConfiguredCancelableAsyncEnumerable`1.Enumerator.MoveNextAsync()\r\n   
at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.ToListAsync[TSource](IQueryable`1 source, CancellationToken cancellationToken)\r\n   
at System.Runtime.CompilerServices.AsyncMethodBuilderCore.Start[TStateMachine](TStateMachine& stateMachine)\r\n   
at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.ToListAsync[TSource](IQueryable`1 source, CancellationToken cancellationToken)\r\n   
at EMVS.Fichas.NetCore.API.Controllers.TemasPisosController.<>c__DisplayClass3_0.<<GetTemasPisos>b__0>d.MoveNext()\r\n   
at System.Runtime.CompilerServices.AsyncMethodBuilderCore.Start[TStateMachine](TStateMachine& stateMachine)\r\n   
at EMVS.Fichas.NetCore.API.Controllers.TemasPisosController.<>c__DisplayClass3_0.<GetTemasPisos>b__0(ICacheEntry entry)\r\n   
at Microsoft.Extensions.Caching.Memory.CacheExtensions.GetOrCreateAsync[TItem](IMemoryCache cache, Object key, Func`2 factory)\r\n   
at System.Runtime.CompilerServices.AsyncMethodBuilderCore.Start[TStateMachine](TStateMachine& stateMachine)\r\n   
at Microsoft.Extensions.Caching.Memory.CacheExtensions.GetOrCreateAsync[TItem](IMemoryCache cache, Object key, Func`2 factory)\r\n   
at EMVS.Fichas.NetCore.API.Controllers.TemasPisosController.GetTemasPisos(BaseFilterDto filter)\r\n   
at System.Runtime.CompilerServices.AsyncMethodBuilderCore.Start[TStateMachine](TStateMachine& stateMachine)\r\n   
at EMVS.Fichas.NetCore.API.Controllers.TemasPisosController.GetTemasPisos(BaseFilterDto filter)\r\n   
at lambda_method(Closure , Object , Object[] )\r\n   at Microsoft.Extensions.Internal.ObjectMethodExecutor.ExecuteAsync(Object target, Object[] parameters)\r\n   
at Microsoft.AspNetCore.Mvc.Infrastructure.ActionMethodExecutor.AwaitableObjectResultExecutor.Execute(IActionResultTypeMapper mapper, ObjectMethodExecutor executor, Object controller, Object[] arguments)\r\n   
at System.Runtime.CompilerServices.AsyncMethodBuilderCore.Start[TStateMachine](TStateMachine& stateMachine)\r\n   
at Microsoft.AspNetCore.Mvc.Infrastructure.ActionMethodExecutor.AwaitableObjectResultExecutor.Execute(IActionResultTypeMapper mapper, ObjectMethodExecutor executor, Object controller, Object[] arguments)\r\n   
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.InvokeActionMethodAsync()\r\n   
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)\r\n   
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.InvokeNextActionFilterAsync()\r\n   
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)\r\n   
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.InvokeInnerFilterAsync()\r\n   
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)\r\n   
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.InvokeNextResourceFilter()\r\n   
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)\r\n   
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.InvokeFilterPipelineAsync()\r\n   
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.InvokeAsync()\r\n   
at Microsoft.AspNetCore.Mvc.Routing.ActionEndpointFactory.<>c__DisplayClass7_0.<CreateRequestDelegate>b__0(HttpContext context)\r\n   
at Microsoft.AspNetCore.Routing.EndpointMiddleware.Invoke(HttpContext httpContext)\r\n   
at EMVS.Arq.Configuracion.NetCore.Middleware.ExceptionMiddleware.InvokeAsync(HttpContext httpContext, IAppEmailService appEmailService, IConfiguration configuration)\r\n   
at System.Runtime.CompilerServices.AsyncMethodBuilderCore.Start[TStateMachine](TStateMachine& stateMachine)\r\n   
at EMVS.Arq.Configuracion.NetCore.Middleware.ExceptionMiddleware.InvokeAsync(HttpContext httpContext, IAppEmailService appEmailService, IConfiguration configuration)\r\n   
at Microsoft.AspNetCore.Builder.UseMiddlewareExtensions.<>c__DisplayClass4_1.<UseMiddleware>b__2(HttpContext context)\r\n   
at EMVS.Arq.Configuracion.NetCore.Middleware.RequestResponseLoggingMiddleware.LogResponse(HttpContext context)\r\n   
at System.Runtime.CompilerServices.AsyncMethodBuilderCore.Start[TStateMachine](TStateMachine& stateMachine)\r\n   
at EMVS.Arq.Configuracion.NetCore.Middleware.RequestResponseLoggingMiddleware.LogResponse(HttpContext context)\r\n   
at EMVS.Arq.Configuracion.NetCore.Middleware.RequestResponseLoggingMiddleware.InvokeAsync(HttpContext context)\r\n   
at System.Runtime.CompilerServices.AsyncMethodBuilderCore.Start[TStateMachine](TStateMachine& stateMachine)\r\n   
at EMVS.Arq.Configuracion.NetCore.Middleware.RequestResponseLoggingMiddleware.InvokeAsync(HttpContext context)\r\n   
at Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware.Invoke(HttpContext context)\r\n   
at Swashbuckle.AspNetCore.SwaggerUI.SwaggerUIMiddleware.Invoke(HttpContext httpContext)\r\n   
at System.Runtime.CompilerServices.AsyncMethodBuilderCore.Start[TStateMachine](TStateMachine& stateMachine)\r\n   
at Swashbuckle.AspNetCore.SwaggerUI.SwaggerUIMiddleware.Invoke(HttpContext httpContext)\r\n   
at Swashbuckle.AspNetCore.Swagger.SwaggerMiddleware.Invoke(HttpContext httpContext, ISwaggerProvider swaggerProvider)\r\n   
at System.Runtime.CompilerServices.AsyncMethodBuilderCore.Start[TStateMachine](TStateMachine& stateMachine)\r\n   
at Swashbuckle.AspNetCore.Swagger.SwaggerMiddleware.Invoke(HttpContext httpContext, ISwaggerProvider swaggerProvider)\r\n   
at Microsoft.AspNetCore.Builder.UseMiddlewareExtensions.<>c__DisplayClass4_1.<UseMiddleware>b__2(HttpContext context)\r\n   
at Ben.Diagnostics.BlockingDetectionMiddleware.Invoke(HttpContext httpContext)\r\n   
at System.Runtime.CompilerServices.AsyncMethodBuilderCore.Start[TStateMachine](TStateMachine& stateMachine)\r\n   
at Ben.Diagnostics.BlockingDetectionMiddleware.Invoke(HttpContext httpContext)\r\n   
at Microsoft.AspNetCore.CookiePolicy.CookiePolicyMiddleware.Invoke(HttpContext context)\r\n   
at Microsoft.AspNetCore.Routing.EndpointRoutingMiddleware.Invoke(HttpContext httpContext)\r\n   
at Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware.Invoke(HttpContext context)\r\n   
at Microsoft.AspNetCore.ResponseCompression.ResponseCompressionMiddleware.Invoke(HttpContext context)\r\n   
at System.Runtime.CompilerServices.AsyncMethodBuilderCore.Start[TStateMachine](TStateMachine& stateMachine)\r\n   
at Microsoft.AspNetCore.ResponseCompression.ResponseCompressionMiddleware.Invoke(HttpContext context)\r\n   
at EMVS.Arq.Configuracion.NetCore.Middleware.ResponseCompressionQualityMiddleware.Invoke(HttpContext context)\r\n   
at System.Runtime.CompilerServices.AsyncMethodBuilderCore.Start[TStateMachine](TStateMachine& stateMachine)\r\n   
at EMVS.Arq.Configuracion.NetCore.Middleware.ResponseCompressionQualityMiddleware.Invoke(HttpContext context)\r\n   
at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)\r\n   
at System.Runtime.CompilerServices.AsyncMethodBuilderCore.Start[TStateMachine](TStateMachine& stateMachine)\r\n   
at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)\r\n   
at Microsoft.AspNetCore.HostFiltering.HostFilteringMiddleware.Invoke(HttpContext context)\r\n   
at Microsoft.AspNetCore.Hosting.HostingApplication.ProcessRequestAsync(Context context)\r\n   
at Microsoft.AspNetCore.Server.IIS.Core.IISHttpContextOfT`1.ProcessRequestAsync()\r\n   
at System.Runtime.CompilerServices.AsyncMethodBuilderCore.Start[TStateMachine](TStateMachine& stateMachine)\r\n   
at Microsoft.AspNetCore.Server.IIS.Core.IISHttpContextOfT`1.ProcessRequestAsync()\r\n   
at Microsoft.AspNetCore.Server.IIS.Core.IISHttpContext.HandleRequest()\r\n   
at System.Runtime.CompilerServices.AsyncMethodBuilderCore.Start[TStateMachine](TStateMachine& stateMachine)\r\n   
at Microsoft.AspNetCore.Server.IIS.Core.IISHttpContext.HandleRequest()\r\n   
at Microsoft.AspNetCore.Server.IIS.Core.IISHttpContext.Execute()\r\n   
at System.Threading.ThreadPoolWorkQueue.Dispatch()\r\n   
at System.Threading._ThreadPoolWaitCallback.PerformWaitCallback()\r\n"

I understand my code is async, then, Why does the library mark that code as a possible code lock?

Thanks,

[sadik7266]

I am getting similar kind of error and couldn't find the method which one blocking the code.
Please review logs below:

[12:40:05.621 WRN] Ben.Diagnostics.BlockingMonitor: Blocking method has been invoked and blocked, this can lead to threadpool starvation. at System.Threading.Monitor.ReliableEnter(Object obj, Boolean& lockTaken) at System.IO.Pipelines.Pipe.AllocateWriteHeadSynchronized(Int32 sizeHint) at System.IO.Pipelines.Pipe.GetSpan(Int32 sizeHint) at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Infrastructure.PipeWriterHelpers.ConcurrentPipeWriter.GetSpan(Int32 sizeHint) at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.Http1OutputProducer.WriteChunkAsync(ReadOnlySpan1 buffer, CancellationToken cancellationToken)
at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.HttpProtocol.WritePipeAsync(ReadOnlyMemory1 data, CancellationToken cancellationToken) at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.HttpResponseStream.WriteAsync(Byte[] buffer, Int32 offset, Int32 count, CancellationToken cancellationToken) at Prometheus.TextSerializer.WriteMetricAsync(Byte[] identifier, Double value, CancellationToken cancel) at System.Runtime.CompilerServices.AsyncMethodBuilderCore.Start[TStateMachine](TStateMachine& stateMachine) at Prometheus.TextSerializer.WriteMetricAsync(Byte[] identifier, Double value, CancellationToken cancel) at Prometheus.Histogram.Child.CollectAndSerializeImplAsync(IMetricsSerializer serializer, CancellationToken cancel) at System.Runtime.CompilerServices.AsyncMethodBuilderCore.Start[TStateMachine](TStateMachine& stateMachine) at Prometheus.Histogram.Child.CollectAndSerializeImplAsync(IMetricsSerializer serializer, CancellationToken cancel) at Prometheus.Collector1.CollectAndSerializeAsync(IMetricsSerializer serializer, CancellationToken cancel)
at System.Runtime.CompilerServices.AsyncMethodBuilderCore.Start[TStateMachine](TStateMachine& stateMachine)
at Prometheus.Collector1.CollectAndSerializeAsync(IMetricsSerializer serializer, CancellationToken cancel) at Prometheus.CollectorRegistry.CollectAndSerializeAsync(IMetricsSerializer serializer, CancellationToken cancel) at System.Runtime.CompilerServices.AsyncMethodBuilderCore.Start[TStateMachine](TStateMachine& stateMachine) at Prometheus.CollectorRegistry.CollectAndSerializeAsync(IMetricsSerializer serializer, CancellationToken cancel) at Prometheus.MetricServerMiddleware.Invoke(HttpContext context) at System.Runtime.CompilerServices.AsyncMethodBuilderCore.Start[TStateMachine](TStateMachine& stateMachine) at Prometheus.MetricServerMiddleware.Invoke(HttpContext context) at Microsoft.AspNetCore.Builder.Extensions.MapWhenMiddleware.Invoke(HttpContext context) at System.Runtime.CompilerServices.AsyncMethodBuilderCore.Start[TStateMachine](TStateMachine& stateMachine) at Microsoft.AspNetCore.Builder.Extensions.MapWhenMiddleware.Invoke(HttpContext context) at Microsoft.AspNetCore.Builder.Extensions.MapMiddleware.Invoke(HttpContext context) at System.Runtime.CompilerServices.AsyncMethodBuilderCore.Start[TStateMachine](TStateMachine& stateMachine) at Microsoft.AspNetCore.Builder.Extensions.MapMiddleware.Invoke(HttpContext context) at Microsoft.AspNetCore.Builder.Extensions.MapWhenMiddleware.Invoke(HttpContext context) at System.Runtime.CompilerServices.AsyncMethodBuilderCore.Start[TStateMachine](TStateMachine& stateMachine) at Microsoft.AspNetCore.Builder.Extensions.MapWhenMiddleware.Invoke(HttpContext context) at Serilog.AspNetCore.RequestLoggingMiddleware.Invoke(HttpContext httpContext) at System.Runtime.CompilerServices.AsyncMethodBuilderCore.Start[TStateMachine](TStateMachine& stateMachine) at Serilog.AspNetCore.RequestLoggingMiddleware.Invoke(HttpContext httpContext) at Ben.Diagnostics.BlockingDetectionMiddleware.Invoke(HttpContext httpContext) at System.Runtime.CompilerServices.AsyncMethodBuilderCore.Start[TStateMachine](TStateMachine& stateMachine) at Ben.Diagnostics.BlockingDetectionMiddleware.Invoke(HttpContext httpContext) at Microsoft.AspNetCore.HostFiltering.HostFilteringMiddleware.Invoke(HttpContext context) at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.HttpProtocol.ProcessRequests[TContext](IHttpApplication1 application)
at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Runtime.CompilerServices.AsyncTaskMethodBuilder1.AsyncStateMachineBox1.MoveNext(Thread threadPoolThread)
at System.Threading.ThreadPoolWorkQueue.Dispatch()`

Thanks!

[JanEggers]

@ignaciosalazarcalle Microsoft.Data.SqlClient.TdsParser.CheckResetConnection is a blocking call in sql server client.
@sadik7266 System.IO.Pipelines.Pipe.AllocateWriteHeadSynchronized is a blocking call in System.IO.Pipelines.Pipe

nothing you can do about except open an issue in their repos maybe it can/will be fixed there.