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https://issues.apache.org/jira/browse/OAK-12214?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Rishabh Daim resolved OAK-12214.
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Fix Version/s: 2.2.0
Resolution: Fixed
> SegmentCache: L1 hits should notify L2 (caffeine) to keep frequency/recency
> accurate
> ------------------------------------------------------------------------------------
>
> Key: OAK-12214
> URL: https://issues.apache.org/jira/browse/OAK-12214
> Project: Jackrabbit Oak
> Issue Type: Task
> Reporter: Rishabh Daim
> Assignee: Rishabh Daim
> Priority: Critical
> Fix For: 2.2.0
>
>
> *Segment cache (L2)*: Caffeine W-TinyLFU and Guava LRU only learn about
> accesses that go through _SegmentCache.getSegment()_. Production traffic
> often hits _SegmentId.getSegment()_ and returns the memoized segment from L1
> without touching L2. That made eviction policies act on stale
> frequency/recency while the JVM was still reading “hot” segments from L1 —
> wrong evictions, extra TAR reads, and skewed benchmarks vs reality.
> This was working for Guava, since it was using the LRU eviction policy.
> *Fix*: On every L1 hit, call _SegmentCache.recordHit(SegmentId)_, which
> performs _cache.getIfPresent(id)_ on the backing L2 so policies see real
> usage, plus existing hit accounting.
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