When Does Asp.Net Remove Expired Cache Items?

Question

When you add an item to the System.Web.Caching.Cache with an absolute expiration date, as in the following example, how does Asp.Net behave? Does it:

Answer 1

Expired items aren't immediately removed from the cache, they're just marked as expired. You don't get a callback until a cache miss. I ran into this back in the ASP.NET 1.1 days, and it hasn't changed.

There may be cases where expired items are removed immediately - such as if there's low memory and high CPU - but you can't count on it.

I usually use a timer that reloads the cache on a regular basis.