https://cache2k.org/ Refresh ahead 기능이 있음 Features at a glance Small jar file (less than 400k) with no external dependencies Fastest access times, due to non blocking and wait free access of cached values, Blog article Pure Java code, no use of sun.misc.Unsafe Thread safe, with a complete set of atomic operations Resilience and smart exception handling Null value support, see User Guide - Null V..