Kristian Williams Kristian Williams - 3 months ago 45
ASP.NET (C#) Question

MVC5 hangs on MapSignalR when reconnecting after AppPool cycles

I have the following code in my Startup.SignalR.cs:

using Microsoft.AspNet.SignalR;
using Owin;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Admin
{
public partial class Startup
{
public void ConfigureSignalR(IAppBuilder app)
{
var Config = new HubConfiguration()
{
EnableDetailedErrors = false,
Resolver = new DefaultDependencyResolver()
};

#if DEBUG
Config.EnableDetailedErrors = true;
#endif
// Any connection or hub wire up and configuration should go here
app.MapSignalR();

GlobalHost.Configuration.ConnectionTimeout = TimeSpan.FromSeconds(600);
}
}
}


During the initial loading of the application, everything goes fine, however when the thread is allowed to sleep (left for ~10min) the AppPool is recycled and the thread gets stuck on this line:

app.MapSignalR();


The IDE is stuck with the green arrow and
This is the next statement to execute when this thread returns from the current function.
. However I have no idea what the
current function
in this context is.

Attempting to inspect any local variables results in
Cannot evaluate expression because a native frame is on top of the call stack.
however the Call Stack shows:
Admin.dll!Admin.Startup.ConfigureSignalR(Owin.IAppBuilder app) Line 25
as the top frame...

The code never recovers from this state and the AppPool has to be completely restarted by restarting the debugging session.

Anyone have any explanation for this scenario?

Additional information:
After enabling Debug => Windows => Parrallel Stacks I see a more detailed Stack Trace:

[Managed to Native Transition]
mscorlib.dll!Microsoft.Win32.RegistryKey.OpenSubKey(string name, bool writable)
mscorlib.dll!Microsoft.Win32.RegistryKey.OpenSubKey(string name)
System.dll!System.Diagnostics.PerformanceCounterLib.FindCustomCategory(string category, out System.Diagnostics.PerformanceCounterCategoryType categoryType)
System.dll!System.Diagnostics.PerformanceCounterLib.IsCustomCategory(string machine, string category)
System.dll!System.Diagnostics.PerformanceCounter.InitializeImpl()
System.dll!System.Diagnostics.PerformanceCounter.PerformanceCounter(string categoryName, string counterName, string instanceName, bool readOnly)
Microsoft.AspNet.SignalR.Core.dll!Microsoft.AspNet.SignalR.Infrastructure.PerformanceCounterManager.LoadCounter(string categoryName, string counterName, string instanceName, bool isReadOnly)
Microsoft.AspNet.SignalR.Core.dll!Microsoft.AspNet.SignalR.Infrastructure.PerformanceCounterManager.LoadCounter(string categoryName, string counterName, bool isReadOnly)
Microsoft.AspNet.SignalR.Core.dll!Microsoft.AspNet.SignalR.Infrastructure.PerformanceCounterManager.SetCounterProperties()
Microsoft.AspNet.SignalR.Core.dll!Microsoft.AspNet.SignalR.Infrastructure.PerformanceCounterManager.Initialize(string instanceName, System.Threading.CancellationToken hostShutdownToken)
Microsoft.AspNet.SignalR.Core.dll!Microsoft.AspNet.SignalR.Hosting.HostDependencyResolverExtensions.InitializePerformanceCounters(Microsoft.AspNet.SignalR.IDependencyResolver resolver, string instanceName, System.Threading.CancellationToken hostShutdownToken)
Microsoft.AspNet.SignalR.Core.dll!Microsoft.AspNet.SignalR.Hosting.HostDependencyResolverExtensions.InitializeHost(Microsoft.AspNet.SignalR.IDependencyResolver resolver, string instanceName, System.Threading.CancellationToken hostShutdownToken)
Microsoft.AspNet.SignalR.Core.dll!Owin.OwinExtensions.UseSignalRMiddleware<Microsoft.AspNet.SignalR.Owin.Middleware.HubDispatcherMiddleware>(Owin.IAppBuilder builder, object[] args)
Microsoft.AspNet.SignalR.Core.dll!Owin.OwinExtensions.RunSignalR(Owin.IAppBuilder builder, Microsoft.AspNet.SignalR.HubConfiguration configuration)
Microsoft.AspNet.SignalR.Core.dll!Owin.OwinExtensions.MapSignalR.AnonymousMethod__0(Owin.IAppBuilder subApp)
Microsoft.Owin.dll!Owin.MapExtensions.Map(Owin.IAppBuilder app, Microsoft.Owin.PathString pathMatch, System.Action<Owin.IAppBuilder> configuration)
Microsoft.Owin.dll!Owin.MapExtensions.Map(Owin.IAppBuilder app, string pathMatch, System.Action<Owin.IAppBuilder> configuration)
Microsoft.AspNet.SignalR.Core.dll!Owin.OwinExtensions.MapSignalR(Owin.IAppBuilder builder, string path, Microsoft.AspNet.SignalR.HubConfiguration configuration)
Microsoft.AspNet.SignalR.Core.dll!Owin.OwinExtensions.MapSignalR(Owin.IAppBuilder builder, Microsoft.AspNet.SignalR.HubConfiguration configuration)
Microsoft.AspNet.SignalR.Core.dll!Owin.OwinExtensions.MapSignalR(Owin.IAppBuilder builder)
Admin.dll!Admin.Startup.ConfigureSignalR(Owin.IAppBuilder app) Line 25

Answer

As mentioned by Pawel, I was able to resolve my issue with the use of a dummy Performance Counter as documented here: https://github.com/SignalR/SignalR/issues/3414

// Global.asmx
var tempCounterManager = new TempPerformanceCounterManager();
GlobalHost.DependencyResolver.Register(typeof (IPerformanceCounterManager), () => tempCounterManager);

[....]

// Helper Class
public class TempPerformanceCounterManager : IPerformanceCounterManager
{
    private readonly static PropertyInfo[] _counterProperties = GetCounterPropertyInfo();
    private readonly static IPerformanceCounter _noOpCounter = new NoOpPerformanceCounter();

    public TempPerformanceCounterManager()
    {
        foreach (var property in _counterProperties)
        {
            property.SetValue(this, new NoOpPerformanceCounter(), null);
        }
    }

    public void Initialize(string instanceName, CancellationToken hostShutdownToken)
    {
    }

    public IPerformanceCounter LoadCounter(string categoryName, string counterName, string instanceName, bool isReadOnly)
    {
        return _noOpCounter;
    }

    internal static PropertyInfo[] GetCounterPropertyInfo()
    {
        return typeof(TempPerformanceCounterManager)
            .GetProperties()
            .Where(p => p.PropertyType == typeof(IPerformanceCounter))
            .ToArray();
    }
    public IPerformanceCounter ConnectionsConnected { get; set; }
    public IPerformanceCounter ConnectionsReconnected { get; set; }
    public IPerformanceCounter ConnectionsDisconnected { get; set; }
    public IPerformanceCounter ConnectionsCurrentForeverFrame { get; private set; }
    public IPerformanceCounter ConnectionsCurrentLongPolling { get; private set; }
    public IPerformanceCounter ConnectionsCurrentServerSentEvents { get; private set; }
    public IPerformanceCounter ConnectionsCurrentWebSockets { get; private set; }
    public IPerformanceCounter ConnectionsCurrent { get; private set; }
    public IPerformanceCounter ConnectionMessagesReceivedTotal { get; private set; }
    public IPerformanceCounter ConnectionMessagesSentTotal { get; private set; }
    public IPerformanceCounter ConnectionMessagesReceivedPerSec { get; private set; }
    public IPerformanceCounter ConnectionMessagesSentPerSec { get; private set; }
    public IPerformanceCounter MessageBusMessagesReceivedTotal { get; private set; }
    public IPerformanceCounter MessageBusMessagesReceivedPerSec { get; private set; }
    public IPerformanceCounter ScaleoutMessageBusMessagesReceivedPerSec { get; private set; }
    public IPerformanceCounter MessageBusMessagesPublishedTotal { get; private set; }
    public IPerformanceCounter MessageBusMessagesPublishedPerSec { get; private set; }
    public IPerformanceCounter MessageBusSubscribersCurrent { get; private set; }
    public IPerformanceCounter MessageBusSubscribersTotal { get; private set; }
    public IPerformanceCounter MessageBusSubscribersPerSec { get; private set; }
    public IPerformanceCounter MessageBusAllocatedWorkers { get; private set; }
    public IPerformanceCounter MessageBusBusyWorkers { get; private set; }
    public IPerformanceCounter MessageBusTopicsCurrent { get; private set; }
    public IPerformanceCounter ErrorsAllTotal { get; private set; }
    public IPerformanceCounter ErrorsAllPerSec { get; private set; }
    public IPerformanceCounter ErrorsHubResolutionTotal { get; private set; }
    public IPerformanceCounter ErrorsHubResolutionPerSec { get; private set; }
    public IPerformanceCounter ErrorsHubInvocationTotal { get; private set; }
    public IPerformanceCounter ErrorsHubInvocationPerSec { get; private set; }
    public IPerformanceCounter ErrorsTransportTotal { get; private set; }
    public IPerformanceCounter ErrorsTransportPerSec { get; private set; }
    public IPerformanceCounter ScaleoutStreamCountTotal { get; private set; }
    public IPerformanceCounter ScaleoutStreamCountOpen { get; private set; }
    public IPerformanceCounter ScaleoutStreamCountBuffering { get; private set; }
    public IPerformanceCounter ScaleoutErrorsTotal { get; private set; }
    public IPerformanceCounter ScaleoutErrorsPerSec { get; private set; }
    public IPerformanceCounter ScaleoutSendQueueLength { get; private set; }
}

internal class NoOpPerformanceCounter : IPerformanceCounter
{
    public string CounterName
    {
        get
        {
            return GetType().Name;
        }
    }
    public long Decrement()
    {
        return 0;
    }
    public long Increment()
    {
        return 0;
    }
    public long IncrementBy(long value)
    {
        return 0;
    }
    public long RawValue
    {
        get { return 0; }
        set { }
    }
    public void Close()
    {
    }
    public void RemoveInstance()
    {
    }
    public CounterSample NextSample()
    {
        return CounterSample.Empty;
    }
}