[SOLR-7355] Java 8: ConcurrentLinkedHashMap -> Caffeine

• Type: Task
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 6.0
• Assignee: Shawn Heisey
• Reporter: Ben Manes
• Created: 07/Apr/15 09:26
• Updated: 15/Feb/17 16:41
• Resolved: 08/Apr/15 18:38

Description

When Solr transitions to requiring Java 8, please upgrade to Caffeine. The performance should be relatively the same. The per-instance memory usage should be smaller and Solr may decide to opt-in to use some of the additional features. The only drawback is that the jar size is larger due to code generation, though that may be trimmed over time and usually is not a concern for server-side applications.

ConcurrentLinkedHashMap changes will continue to be minimal, even more so now, and driven by requests from Java 6 users unable to upgrade. Caffeine is ideally the upgrade path for Guava cache users too, which due to Android cannot be significantly modified.

Caffeine: https://github.com/ben-manes/caffeine
Benchmarks: https://github.com/ben-manes/caffeine/wiki/Benchmarks
ConcurrentLinkedHashMap: https://code.google.com/p/concurrentlinkedhashmap

Issue Links

• breaks: SOLR-10141 Caffeine cache causes BlockCache corruption