NitroCache
Extremely fast, scalable, concurrent, pure Java In-memory cache
...The fetch operation from cache are always in constant time, O(c), irrespective of the number of threads accessing the cache or cache size.
NitroCache uses unique custom algorithm inspired by Btree, skiplist and hashing to deliver a constant time cache with lock-less fetches.
For details on using NitroCache, please visit wiki section
Note: For details on performance chart, please refer the performane section of wiki.