Why is NHibernate.Cache.HashtableCacheProvider not intended for production use?

Question

The NHibernate documentation and the book NHibernate In Action state that the cache provider NHibernate.Cache.HashtableCacheProvider is not intended for production use. However, I could not find a reason for this. Does anyone know the reason?

Answer 1

Because it doesn't support any kind of reasonable caching semantics (first example that comes to mind: timeouts), and it basically grows indefinitely.

It's intended for testing only, as it just provides the simplest possible implementation of a local cache.