A lot of them have although I must admit that CS graduates fare noticeably better.

What happens is they know what virtual memory is but can't connect the concepts. It is knowledge without understanding.

Probably not many of them, because it doesn't usually take a graduate to write Java. Especially if your experience with Java is also limited to tools like Spring. I think the question is kind of pointless unless your specifically hiring people to work on an application that needs that sort of thru-put. Most apps don't need it.