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https://issues.apache.org/jira/browse/SOLR-8241?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Shawn Heisey updated SOLR-8241:
-------------------------------
Attachment: SOLR-8241.patch
Updated patch against master. Changes from the previous version:
No changes to SolrCache.java -- those were whitespace only. I've also upgraded
to the newest version of Caffeine currently available (2.3.3). Removed the
unused RemovalCause import. Precommit passes.
At this time, I am leaving LFUCache alone and keeping the new cache as a class
addition. I will make a decision later about whether to replace LFUCache.
I don't have a CHANGES.txt entry yet. That will go in last, once we nail down
what version gets the change. I haven't done anything with tests yet.
> Evaluate W-TinyLfu cache
> ------------------------
>
> Key: SOLR-8241
> URL: https://issues.apache.org/jira/browse/SOLR-8241
> Project: Solr
> Issue Type: Wish
> Components: search
> Reporter: Ben Manes
> Priority: Minor
> Attachments: SOLR-8241.patch, SOLR-8241.patch
>
>
> 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.
> https://github.com/ben-manes/caffeine/wiki/Efficiency
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