IoC: advantages of using a child container in web based app

I'm interested in knowing if t开发者_JS百科here are any advantages to creating a child container for each request in a web based application?

The tech stack I'm using includes StructureMap & ASP.NET MVC, which is not particularly relevant but included as background info.

---

Without a child container, the application container would otherwise be responsible for holding all instances created during the application's lifetime.

That is an enormous memory leak.