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

The NHibernate documentation and the book NHibernate In Action state that the cache provider NHibernate.Cache.HashtableCacheProvider is not inten开发者_开发百科ded for production use. However, I could not find a reason for this. Does anyone know the reason?

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.