Redis 4.0 RC1 is out
The new LRU algorithm (which he calls Last Frequently Used) is in this release.I really enjoyed the blog post on it when it was developed [0].Very cool to see a real-word pragmatic solutions to this common/hard problem developed in the open (and in a very readable code-base). I've read through it thinking about my own LRU use in my own applications!  There are only two hard things in Computer Science: cache invalidation and naming things.
  -- Phil Karlton

[0] http://antirez.com/news/109