Question

We are using Unity as our IoC container in an MVC3 project. We just installed dynatrace, and it is showing an inordinate amount of time spent in a FileSystemWatcher.StartRaisingEvents method, specifically in ReadDirectoryChangesW. This seems to be contributing to bad performance.

Why on earth would Unity be monitoring the file system?

Here's the call stack:

ChildActionExtensions.RenderAction
  HttpServerUtility.Execute
    HttpHandlerUtil+ServerExecuteHttpHandler.Wrap
      UnityControllerFactory.CreateController
        XmlConfigurator.ConfigureAndWatch
          FileSystemWatcher.StartRaisingEvents
            UnsafeNativeMethods.ReadDirectoryChangesW

Here is the UnityControllerFactoryCode

        try
        {
            if (requestContext.RouteData.DataTokens.ContainsKey("area") && !string.IsNullOrWhiteSpace(requestContext.RouteData.DataTokens["area"].ToString()))
            {
                controllerName = string.Format("{0}/{1}", requestContext.RouteData.DataTokens["area"], controllerName);
            }

            controllerName = controllerName.ToLower();

            return _container.Resolve<IController>(controllerName);
        }
        catch (Exception ex)
        {
            if (ex is ResolutionFailedException)
            {
                IMyLogger logger = _container.Resolve<IMyLogger>();
                logger.Error(LogEventIdType.General, ex, "Is the '{0}' controller defined in the Unity Container via RegisterType (in lowercase) in UnityIocBootstrapConfigure?", new object[] {controllerName});
                throw;
            }             
        }

The logger logs to the Windows event log.

Answer 1

Your trace is pointing to XmlConfigurator, which is log4net. log4net stores its configuration in a separate file from the web.config, so it starts a File System Watcher to check if the file has changed to reconfigure itself.

It would seem that the culprit of your performance problems then is log4net, not Unity.