Oak

OakMap is a concurrent Key-Value Map that keeps all keys and values off-heap. This allows storing more data (up to 3 times more data) compare to using the standard JVM heap management, albeit using the same memory footprint. OakMap implements the industry-standard Java8 ConcurrentNavigableMap API. It provides strong (atomic) semantics for read, write, and read-modify-write operations, as well as (non-atomic) range query (scan) operations, both forward and backward. OakMap is optimized for big keys and values, in particular, for incremental maintenance of objects (update in-place). It is faster and scales better with additional CPU cores than the popular Java ConcurrentNavigableMap ConcurrentSkipListMap.