在 AppPool 循环后重新连接时，MVC5 在 MapSignalR 上挂起

Question

我的 Startup.SignalR.cs 中有以下代码：

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);
        }
    }
}

在应用程序的初始加载期间，一切正常，但是当线程被允许休眠（大约 10 分钟）时，AppPool 被回收并且线程卡在这一行：

app.MapSignalR();

IDE 卡在绿色箭头和This is the next statement to execute when this thread returns from the current function. 上。但是我不知道在这种情况下current function 是什么。

尝试检查任何局部变量会导致 Cannot evaluate expression because a native frame is on top of the call stack. 但调用堆栈显示：Admin.dll!Admin.Startup.ConfigureSignalR(Owin.IAppBuilder app) Line 25 作为顶部框架...

代码永远不会从此状态恢复，必须通过重新启动调试会话来完全重新启动 AppPool。

有人对这种情况有什么解释吗？

附加信息： 启用 Debug => Windows => 并行堆栈后，我看到了更详细的堆栈跟踪：

[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 1

另一个解决方法，来自这篇博文： http://www.zpqrtbnk.net/posts/appdomains-threads-cultureinfos-and-paracetamol

app.SanitizeThreadCulture();

public static void SanitizeThreadCulture(this IAppBuilder app)
{
        var currentCulture = CultureInfo.CurrentCulture;

        // at the top of any culture should be the invariant culture,
        // find it doing an .Equals comparison ensure that we will
        // find it and not loop endlessly
        var invariantCulture = currentCulture;
        while (invariantCulture.Equals(CultureInfo.InvariantCulture) == false)
            invariantCulture = invariantCulture.Parent;

        if (ReferenceEquals(invariantCulture, CultureInfo.InvariantCulture))
            return;

        var thread = Thread.CurrentThread;
        thread.CurrentCulture = CultureInfo.GetCultureInfo(thread.CurrentCulture.Name);
        thread.CurrentUICulture = CultureInfo.GetCultureInfo(thread.CurrentUICulture.Name);
}

Answer 2

正如 Pawel 所提到的，我能够使用此处记录的虚拟性能计数器解决我的问题：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;
    }
}

Answer 3

我在这里找到了解决方案：github.com/SignalR/SignalR/issues/3414 截图示例：

public void Configuration(IAppBuilder app)
{
    var task = Task.Run(() => app.MapSignalR());
    task.Wait(300);
    //try again if it fails just to be sure ;)
    if (task.IsCanceled) Task.Run(() => app.MapSignalR()).Wait(300);
}