title: how many instances of controller it takes to handle multiple requests?
body: <p>I'm new to asp.net mvc. I'm reading a book which says sth about synchronous request handling:</p>
  
  <blockquote>
    <p>the controller is being run in a web application server that processes only one request at a time and if that all of the requests target the same action method, and the handler starts processing a request only when it has finished processing the previous one, and for the
    majority of the time, the handler is sitting idle. </p>
  </blockquote>
  
  <p>I'm a little bit confused, I always thought that the application in a web server will create multiple instances of controller classes to server multiple requests, but it seems that there is only one specific controller instance for all time. But isn't that better for the application itself to invoke multiple controller instances to serve multiple requests then we won't have the waiting problem and we don't even need to use asynchronous technique?</p>