Uploaded image for project: 'Solr'
  1. Solr
  2. SOLR-8241

Evaluate W-TinyLfu cache



    • Improvement
    • Status: Resolved
    • Major
    • Resolution: Fixed
    • None
    • 8.3
    • search
    • None


      SOLR-2906 introduced an LFU cache and in-progress SOLR-3393 makes it O(1). The discussions seem to indicate that the higher hit rate (vs LRU) is offset by the slower performance of the implementation. An original goal appeared to be to introduce ARC, a patented algorithm that uses ghost entries to retain history information.

      My analysis of Window TinyLfu indicates that it may be a better option. It uses a frequency sketch to compactly estimate an entry's popularity. It uses LRU to capture recency and operate in O(1) time. When using available academic traces the policy provides a near optimal hit rate regardless of the workload.

      I'm getting ready to release the policy in Caffeine, which Solr already has a dependency on. But, the code is fairly straightforward and a port into Solr's caches instead is a pragmatic alternative. More interesting is what the impact would be in Solr's workloads and feedback on the policy's design.



        1. caffeine-benchmark.txt
          6 kB
          Andrzej Bialecki
        2. EvictionBenchmark.png
          86 kB
          Andrzej Bialecki
        3. GetPutBenchmark.png
          57 kB
          Andrzej Bialecki
        4. proposal.patch
          19 kB
          Ben Manes
        5. solr_caffeine.patch.gz
          2 kB
          Ben Manes
        6. solr_jmh_results.json
          18 kB
          Ben Manes
        7. SOLR-8241.patch
          53 kB
          Andrzej Bialecki
        8. SOLR-8241.patch
          38 kB
          Andrzej Bialecki
        9. SOLR-8241.patch
          31 kB
          Andrzej Bialecki
        10. SOLR-8241.patch
          19 kB
          Ben Manes
        11. SOLR-8241.patch
          11 kB
          Shawn Heisey
        12. SOLR-8241.patch
          14 kB
          Ben Manes



            ab Andrzej Bialecki
            ben.manes Ben Manes
            7 Vote for this issue
            12 Start watching this issue