问System.Runtime.CallbackException in DurableInstancing

EN

public class WorkflowHost
{
    private readonly List<string> _services = new List<string>();

    private readonly Dictionary<string, WorkflowServiceHost> _hosts = new Dictionary<string, WorkflowServiceHost>();

    public WorkflowHost(IList<string> serviceNames)
    {
        foreach (string serviceName in serviceNames)
        {
            _services.Add(serviceName);
        } 
    }

    public void Start() 
    { 
        if (_hosts.Count > 0) 
        { 
            Stop(); 
        } 

        foreach(string serviceName in _services) 
        {
            WorkflowService service = LoadService(serviceName);                
            WorkflowServiceHost host = new WorkflowServiceHost(service);

            host.Faulted += new EventHandler(host_Faulted);

            try
            {
                host.Open();
            }
            catch (Exception e)
            {
                Debug.WriteLine(e.Message);
            }

            _hosts.Add(serviceName, host); 
        } 
    }

    void host_Faulted(object sender, EventArgs e)
    {
        Debug.WriteLine("Service Faulted");

        Start();
    }

    public void Stop() 
    { 
        if (_hosts.Count > 0) 
        { 
            foreach (string serviceName in _services) 
            {                    
                IDisposable host = _hosts[serviceName]; 
                host.Dispose(); 
            } 

            _hosts.Clear(); 
        } 
    } 

    private WorkflowService LoadService(String xamlxName)
    {
        string fullFilePath = Path.Combine(@"..\..\..\Services\Sales Funnel Workflow", xamlxName);

        WorkflowService service = XamlServices.Load(fullFilePath) as WorkflowService;

        if (service != null)
        {
            return service;
        }
        else
        {
            throw new NullReferenceException(string.Format("Unable to load service definition from {0}", fullFilePath));
        }
    }
}

<StackTrace>
at System.ServiceModel.Channels.CommunicationObject.OnFaulted()
at System.ServiceModel.Channels.CommunicationObject.Fault()
at System.ServiceModel.Channels.CommunicationObject.Fault(Exception exception)
at  System.ServiceModel.Activities.Dispatcher.DurableInstanceManager.WaitAndHandleStoreEventsCallback(IAsyncResult result)
at System.Runtime.Fx.AsyncThunk.UnhandledExceptionFrame(IAsyncResult result)
at System.Runtime.AsyncResult.Complete(Boolean completedSynchronously)
at System.Runtime.AsyncResult.AsyncCompletionWrapperCallback(IAsyncResult result)
at System.Runtime.Fx.AsyncThunk.UnhandledExceptionFrame(IAsyncResult result)
at System.Runtime.AsyncResult.Complete(Boolean completedSynchronously)
at System.Runtime.DurableInstancing.InstanceHandle.WaitForEventsAsyncResult.Canceled()
at System.Runtime.DurableInstancing.InstanceHandle.Free()
at System.Activities.DurableInstancing.SqlWorkflowInstanceStoreLock.MarkInstanceOwnerLost(Int64 surrogateLockOwnerId)
at System.Activities.DurableInstancing.SqlWorkflowInstanceStoreLock.MarkInstanceOwnerLost(Int64 surrogateLockOwnerId, Boolean hasModificationLock)
at System.Activities.DurableInstancing.LockRenewalTask.HandleError(Exception exception)
at System.Activities.DurableInstancing.PersistenceTask.CommandCompletedCallback(IAsyncResult result)
at System.Runtime.Fx.AsyncThunk.UnhandledExceptionFrame(IAsyncResult result)
at System.Runtime.AsyncResult.Complete(Boolean completedSynchronously)
at System.Runtime.AsyncResult.Complete(Boolean completedSynchronously, Exception exception)
at System.Activities.DurableInstancing.SqlWorkflowInstanceStoreAsyncResult.StartOperation()
at System.Activities.DurableInstancing.SqlWorkflowInstanceStoreAsyncResult.StartOperationCallback(Object state)
at System.Runtime.ActionItem.DefaultActionItem.Invoke()
at System.Runtime.ActionItem.CallbackHelper.InvokeWithoutContext(Object state)
at System.Runtime.IOThreadScheduler.ScheduledOverlapped.IOCallback(UInt32 errorCode, UInt32 numBytes, NativeOverlapped* nativeOverlapped)
at System.Runtime.Fx.IOCompletionThunk.UnhandledExceptionFrame(UInt32 error, UInt32 bytesRead, NativeOverlapped* nativeOverlapped)
at System.Threading._IOCompletionCallback.PerformIOCompletionCallback(UInt32 errorCode, UInt32 numBytes, NativeOverlapped* pOVERLAP)
</StackTrace>
<ExceptionString>System.Runtime.CallbackException: A user callback threw an exception.  Check the exception stack and inner exception to determine the callback that failed. ---&gt; System.ServiceModel.CommunicationObjectFaultedException: The communication object, System.ServiceModel.Activities.WorkflowServiceHost, cannot be used for communication because it is in the Faulted state.
   at System.ServiceModel.Channels.CommunicationObject.Close(TimeSpan timeout)
   at System.ServiceModel.ServiceHostBase.System.IDisposable.Dispose()
   at Zeller.SalesFunnel.WorkFlow.Service.WorkflowHost.Stop() in C:\Projects\TFS\Zeller Corp Toolkit\Main\Toolkit\Services\ZSalesFunnelService\Zeller.SalesFunnel.WorkFlow.Service\WorkflowHost.cs:line 67
   at Zeller.SalesFunnel.WorkFlow.Service.WorkflowHost.Start() in C:\Projects\TFS\Zeller Corp Toolkit\Main\Toolkit\Services\ZSalesFunnelService\Zeller.SalesFunnel.WorkFlow.Service\WorkflowHost.cs:line 30
   at Zeller.SalesFunnel.WorkFlow.Service.WorkflowHost.host_Faulted(Object sender, EventArgs e) in C:\Projects\TFS\Zeller Corp Toolkit\Main\Toolkit\Services\ZSalesFunnelService\Zeller.SalesFunnel.WorkFlow.Service\WorkflowHost.cs:line 57
   at System.EventHandler.Invoke(Object sender, EventArgs e)
   at System.ServiceModel.Channels.CommunicationObject.OnFaulted()
   --- End of inner exception stack trace ---</ExceptionString>
<InnerException>
<ExceptionType>System.ServiceModel.CommunicationObjectFaultedException, System.ServiceModel, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</ExceptionType>
<Message>The communication object, System.ServiceModel.Activities.WorkflowServiceHost, cannot be used for communication because it is in the Faulted state.</Message>
<StackTrace>
at System.ServiceModel.Channels.CommunicationObject.Close(TimeSpan timeout)
at System.ServiceModel.ServiceHostBase.System.IDisposable.Dispose()
at Zeller.SalesFunnel.WorkFlow.Service.WorkflowHost.Stop() in C:\Projects\TFS\Zeller Corp Toolkit\Main\Toolkit\Services\ZSalesFunnelService\Zeller.SalesFunnel.WorkFlow.Service\WorkflowHost.cs:line 67
at Zeller.SalesFunnel.WorkFlow.Service.WorkflowHost.Start() in C:\Projects\TFS\Zeller Corp Toolkit\Main\Toolkit\Services\ZSalesFunnelService\Zeller.SalesFunnel.WorkFlow.Service\WorkflowHost.cs:line 30
at Zeller.SalesFunnel.WorkFlow.Service.WorkflowHost.host_Faulted(Object sender, EventArgs e) in C:\Projects\TFS\Zeller Corp Toolkit\Main\Toolkit\Services\ZSalesFunnelService\Zeller.SalesFunnel.WorkFlow.Service\WorkflowHost.cs:line 57
at System.EventHandler.Invoke(Object sender, EventArgs e)
at System.ServiceModel.Channels.CommunicationObject.OnFaulted()
</StackTrace>
<ExceptionString>System.ServiceModel.CommunicationObjectFaultedException: The communication object, System.ServiceModel.Activities.WorkflowServiceHost, cannot be used for communication because it is in the Faulted state.
   at System.ServiceModel.Channels.CommunicationObject.Close(TimeSpan timeout)
   at System.ServiceModel.ServiceHostBase.System.IDisposable.Dispose()
   at Zeller.SalesFunnel.WorkFlow.Service.WorkflowHost.Stop() in C:\Projects\TFS\Zeller Corp Toolkit\Main\Toolkit\Services\ZSalesFunnelService\Zeller.SalesFunnel.WorkFlow.Service\WorkflowHost.cs:line 67
   at Zeller.SalesFunnel.WorkFlow.Service.WorkflowHost.Start() in C:\Projects\TFS\Zeller Corp Toolkit\Main\Toolkit\Services\ZSalesFunnelService\Zeller.SalesFunnel.WorkFlow.Service\WorkflowHost.cs:line 30
   at Zeller.SalesFunnel.WorkFlow.Service.WorkflowHost.host_Faulted(Object sender, EventArgs e) in C:\Projects\TFS\Zeller Corp Toolkit\Main\Toolkit\Services\ZSalesFunnelService\Zeller.SalesFunnel.WorkFlow.Service\WorkflowHost.cs:line 57
   at System.EventHandler.Invoke(Object sender, EventArgs e)
   at System.ServiceModel.Channels.CommunicationObject.OnFaulted()</ExceptionString>
</InnerException>
</Exception>