KeyPool

This pools internal guarantees are that the max number of values are in the pool at any time, not maximum number of operations. To do the latter application level bounds should be used.

A background reaper thread is kept alive for the length of the key pools life.

When resources are taken from the pool they are received as a Managed. This Managed has a Ref to a Reusable which indicates whether or not the pool can reuse the resource.