System.InvalidOperationException：指定的类别中不存在实例'[private Queue path]'

Question

我正在使用以下代码来获取消息队列计数时间从此方法每15秒调用一次

public JObject GetQueueItemsCount()
{

               JObject returnObject = new JObject();
                int queueCount = 0;
                var queueName = @"" + ConfigurationManager.AppSettings["QueueName"];
                try
                {
                    MessageQueue messageQueue = new MessageQueue(queueName);
                    if (MessageQueue.Exists(queueName))
                    {

                        var queueCounter = new PerformanceCounter("MSMQ Queue", "Messages in Queue", queueName, @"" + ConfigurationManager.AppSettings["MachineName"]);
                        queueCount = (int)queueCounter.NextValue();
                    }


                }
                catch (Exception ex)
                {

                    throw ex;
                }

                finally {
                    returnObject.Add("queueCount", queueCount);
                }
                return returnObject;
            }

问题是有时抛出以下异常：当消息队列计数基本上为新创建的队列变为0时抛出此异常

System.InvalidOperationException: Instance 'xxxxx\private$\xxx_queue' does not exist in the specified Category.
  at xxxxx.BusinessObjects.ControllerRepositories.xxxxRepository.GetQueueItemsCount()
  at lambda_method(Closure , Object , Object[] )
  at System.Web.Http.Controllers.ReflectedHttpActionDescriptor.ActionExecutor.<>c__DisplayClass10.<GetExecutor>b__9(Object instance, Object[] methodParameters)
  at System.Web.Http.Controllers.ReflectedHttpActionDescriptor.ExecuteAsync(HttpControllerContext controllerContext, IDictionary`2 arguments, CancellationToken cancellationToken)
------

Answer 1

我相信这是因为性能计数器要么尚不存在（对于从未有过任何消息的新队列），要么已被删除。由于您无论如何都要实例化MessageQueue对象，因此获得计数的更可靠方法可能是调用messageQueue.GetAllMessages().Length。只要您没有在MessageQueuePropertyFilter中启用Body属性，它就不会非常昂贵。