The document discusses and compares caching technologies for Java applications, specifically Memcached and DistributedMap. It provides an overview of general object cache characteristics and how cache instances work. Memcached is described as an open-source, high-performance distributed memory caching system where each cluster of servers is a single cache instance. DistributedMap is a built-in component of WebSphere Application Server that allows for multiple cache instances within a single JVM. The document outlines some advantages of each system and poses some open questions for further performance comparisons.

1. Caching Technologies for Java Applications Martin Presler-Marshall ICS Performance 09/30/2011

2. Technologies General object cache attributes

3. Memcached

4. DistributedMap (part of Dynacache)

5. General Object Cache Characteristics An object cache is a Key-Value lookup table Similar to java.util.Hashtable Have configurable maximum sizes May be configured number of cache entries or memory size

6. Objects typically discarded on least-recently-used policy when cache is full Some caches may offer other algorithms, such as priority-based schemes Have configurable lifetimes per cache entry Items are automatically discarded once lifetime is exceeded

7. Overview: Cache Instances A cache instance is a logical grouping of cache keys & values

8. Identical keys in two separate cache instances do not collide

9. Cache statistics can typically be monitored on an instance level