MemoryCache空:设置后返回null

I have a problem with an MVC 3 application that is using the new .NET 4 System.Runtime.Caching MemoryCache. I notice that after a seemingly unpredictable time, it stops caching stuff, and acts like it's empty. Consider this bit of code that I took straight from a test View in ASP.NET MVC:I have a problem with an MVC 3 application that