Redis: REmote DIctionary Server
- 1. Redis REmote DIctionary Server Ezra Zygmuntowicz #redis twitter: @ezmobius
- 2. • Fast, in memory key/value store • STRING, LIST, SET & ZSET data types • Persistence via async snapshots or AOF • Perfect Data Structure/State/Cache Server
- 4. Data Structure Server Key:String => Value:String
- 5. Data Structure Server Key:String => Value:String Key:String => Value:List
- 6. Data Structure Server Key:String => Value:String Key:String => Value:List Key:String => Value:Set
- 7. Data Structure Server Key:String => Value:String Key:String => Value:List Key:String => Value:Set Key:String => Value:Zset
- 8. Operations on any Type • Exists, Del, Type • Keys, Randomkey • Rename, RenameNX • Dbsize, Select, Move, Flushdb, Flushall • TTL, Expire
- 9. Operations on STRING’s • Get, Set, GetSet, SetNX • Mget, Mset, MgetNX, MsetNX • Incr, Incrby • Decr, Decrby
- 10. Operations on LISTS’s • Atomic Operations: • Push/Pop • Index (array indexing) • Lrange, Ltrim, Llen • Blpop, Brpop • RpopLpush, BRpopLpush
- 11. Operations on SET’s • Sadd, Srem, Spop, Smove • Scard, Sismember, Smembers, Srandmember • Sinter, Sinterstore, Sunion, Sunionstore • Sdiff, Sdiffstore
- 12. Operations on ZSET’s • Zadd, Zrem, Zincrby • Zrange, Zrevrange • Zrangebyscore, Zcard • Zscore, Zremrangebyscore
- 13. Seems cool, but what are the use cases? • Memcached on Steroids • Tag Clouds, Leaderboards • Stat collections, circular log buffers • Share state between processes • A/B testing • REDIStribute your load
- 14. Example: Tagging
- 15. Example: Tagging SADD article:42 magick SADD article:42 unicorns SADD article:42 rainbows
- 16. Example: Tagging SADD article:42 magick SADD article:42 unicorns SADD article:42 rainbows SADD article:12 magick SADD article:12 bar SADD article:12 qux SADD article:12 foo
- 17. Example: Tagging SADD article:42 magick SADD article:42 unicorns SADD article:42 rainbows SADD article:12 magick SADD article:12 bar SADD article:12 qux SADD article:12 foo SINTER article:42 article:12 #=> magick
- 18. Example: Fair Work Scheduler
- 19. Example: Fair Work Scheduler
- 20. Example: Fair Work Scheduler Each worker node periodically issues: ZADD worker:nodes 1.5 hostname 1.5 is the load ave of the host
- 21. Example: Fair Work Scheduler Each worker node listens for work with: BLPOP hostname 10
- 22. Example: Fair Work Scheduler When a producer wants to issue a work request: ZRANGE worker:nodes 0 2 returns top 3 least loaded nodes
- 23. Example: Fair Work Scheduler Pick a random node out of the 3 least loaded nodes in order to add jitter so we don’t overload hosts
- 24. Example: Fair Work Scheduler Then issue the work request: LPUSH hostname {“work”: {“foo”: “bar”}}
- 25. Example: Fair Work Scheduler This setup uses ZSETS and the load average as a score in order to evenly distribute load across a farm of worker instances listening for jobs with BLPOP
- 27. Example: AMQP message de-dupe Route messages through 2 separate rabbitmq brokers for redundancy Use redis for message de-dupe by tagging messages with a guid Use guid as key into redis Use SETNX when setting the guid key so first one wins and second messages gets discarded as already received
- 28. Other Ideas • Distributed Lock Manager for process coordination • Full Text Inverted Index Lookups • Caching with extra smarts using lists, sets and atomic ops on said structures • Share data structures between multiple processes like a blackboard/tuplespace
- 29. Speed • 110k GETS/SETS/second on average linux box • Mostly faster then memcached for same ops • Event Driven, can handle thousands of clients with epoll/kqueue support • Ops happen in memory, persistence is async so everything is very fast
- 30. Persistence • Async Snapshots with configurable triggers • Append Only File: AOF • Redis 2.0 Virtual Memory
- 31. Replication • Built in Master -> Slave Async replication • Create replication chains as needed
- 32. Sharding • Client side sharding (like memcached) • Consistent ring hashing • Special case keys “foo{tags}” for operations on keys that must live on the same server in ruby client
- 33. Redactor • Simple Actor Library based around Redis