Azure ServiceBus OnMessage is blocking the call or not?

We use Azure ServiceBus queues to handle large volumes of client requests. However, the call OnMessage

appears to be a blocking call, however, blocking that call is incredibly inconsistent if it is indeed a blocking call.

What I'm trying to accomplish is to keep track of the queue permanently from the web service application (to resolve the metric from the running application)

I am creating a subscription below:

protected virtual void Subscribe(string queueName, Func<QueueRequest, bool> callback)
{
    var client = GetClient(queueName, PollingTimeout);
    var transformCallback = new Action<BrokeredMessage>((message) =>
    {
        try
        {
            var request = message.ToQueueRequest();
            if (callback(request))
            {
                message.Complete();
            }
            else
            {
                message.Abandon();
            }
        }
        catch (Exception ex)
        {
            //TODO: Log the error
            message.Abandon();
        }
    });
    var options = new OnMessageOptions
    {
        MaxConcurrentCalls = _config.GetInt("MaxThreadsPerQueue"),
        AutoComplete = false
    };
    options.ExceptionReceived += OnMessageError;
    client.OnMessage(transformCallback, options);
}

      

        
        
        
      

    

If I only have a one-time subscription, the application stops watching the queue and thus stops processing messages. However, if I put a while loop in my call to subscribe. So with much hesitation, I wrote the below snippet to re-submit if this one is OnMessage

complete.

protected void MonitorQueue()
{
    IsRunning = true;
    while (IsRunning)
    {
        try
        {
            Log.Info("MonitoringThread: OnMessage beginning logging for {0}", QueueName);
            QueueClient.Subscribe(QueueName, Processor);
            Log.Info("MonitoringThread:  OnMessage ended logging for {0}", QueueName);
        }
        catch (Exception ex)
        {
            IsRunning = false;
            Log.Error("MonitoringThread: Error in subscription for {0}: ", ex, QueueName);
        }

        if (SleepBeforeReinit > 0 && IsRunning)
        {
            Thread.Sleep(SleepBeforeReinit);
        }
    }
}

      

        
        
        
      

    

This fixed the issue of messages ending with a dead letter due to not being raised, however it caused other problems.

When OnMessage is a billable operation, it bothers me when I see a log file telling me that the queue starts and ends in less than a second and my log file grows in size very quickly.

I have it set to MessagingFactory

OperationTimeout

OperationTimeout

1 day, but that doesn't seem to affect the frequency of the subscription open / close status as I expected.

I have seen many examples of doing this as a worker role, however this will not do what we are trying to do. I am currently plugging this in from the Global.asax.cs of our web app. Any advice is appreciated!