by bill-s, 2013-07-27T08:01:04.000Z
The .NET 4.5 Framework introduced the new async/await asynchronous programming model. With ASP.NET MVC 4 comes the application of the async/await model to controller actions. A traditional ASP.NET MVC control action will be synchronous by nature; this means a thread in the ASP.NET Thread Pool is blocked until the action completes. Calling an asynchronous controller action will not block a thread in the thread pool.