When a busy registered object finishes its work, it calls the HostingEnvironment.DecrementBusyCount method to signal the System.Web.Hosting.HostingEnvironment object that it has completed processing and to reduce the count of busy objects by one.
If the busy count is greater than zero, the hosting application will not time out even if there are no pending requests.
There must be a call to the HostingEnvironment.DecrementBusyCount method for each call to the HostingEnvironment.IncrementBusyCount method.