Caching technology comparison
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Dynacache and Memcached are caching technologies for Java applications. Dynacache is built into WebSphere Application Server and caches content in JVM memory, allowing cache operations through POJO calls. Memcached is an open-source, high-performance distributed memory caching system where keys and values are transmitted over TCP/IP and cached content is not stored in JVM memory. Each technology has advantages such as Dynacache supporting memory and disk storage with size restrictions and faster operations through POJO calls without serialization, while Memcached does not consume memory in the Java heap.
Caching technology comparison
- 1. Dynacache vs Memcached - Caching Technologies for Java Applications
- 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 a 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 Have configurable lifetimes per cache entry
- 7. Overview: Memcached “ Free & open source, high-performance, distributed memory object caching system” (from memcached.org)
- 8. Main components: memcached server – standalone server storing cached items
- 9. memcached client software Available for multiple programming languages
- 10. Keys & values must be transmitted over TCP/IP Cluster design: Client uses hashing algorithm to assign keys to servers
- 11. Each key is cached on at most one server
- 12. Explicit invalidations go only to the server which should store that key
- 13. Overview: DistributedMap Built-in component in WAS Network Deployment Only available to Java clients Content is cached in JVM memory Cache operations are POJO calls Multiple cache instances can be created Each is treated separately for synchronization, LRU and invalidation Cluster design: Cache keys may be cached in multiple nodes
- 14. Explicit invalidation notifies peers to discard the cache key
- 15. Option available to push entries to peers on cache insert
- 16. Advantages of Each Technology Dynacache Memory and disk storage for cache with ability to restrict size in terms of # of entries and # of bytes Fast cache operations The key raison d'etre for a cache
- 17. Lookups through POJO calls - no network delays
- 18. No serialization/ deserialization of keys and values – lower CPU consumption Mature, well-supported part of WAS Used in Connections, other ICS products
- 19. “ We know the developers” Priority-based cache algorithm available
- 20. Variety of tools available for Administering, Monitoring and Configuration integrated with WAS Mbean, Extended Cache Monitor Higher QOS with WebSphere eXtreme scale integration
- 21. Leverages scalable, resilient and field tested WAS replication & HAManager infrastructure
- 22. Comprehensive cache metrics available including mbean and PMI statistics
- 23. Can be plugged in as an OpenJPA L2 cache Memcached Does not consume memory in Java heap This is less important as we move to 64-bit JVMs Single instance of each cache key No peer-to-peer traffic on invalidations Usable in Tomcat, WAS CE, php applications
Editor's Notes
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