Caffeine vs Ristretto

Caffeine is a free, open-source in-memory caching library for Java, distributed under the Apache License, Version 2.0. It provides an API inspired by Google Guava and can load entries automatically, including asynchronously. Size-based eviction uses configured limits with frequency and recency, while entries can expire according to time since their last access or write. When a stale entry is first requested, Caffeine can refresh it asynchronously. Other functions include weak keys, weak or soft values, removal notifications, writes to external resources, and cache statistics. The project offers JSR-107 JCache, Guava adapters, and a simulation extension, with community integrations listed for Spring Cache, Play Framework, Micronaut, Quarkus, and Apache Camel. The project directs users to Maven Central and provides Gradle coordinates for the core library and optional extensions. Version 3.x is intended for Java 11 or newer; earlier Java versions use 2.x. Maven Central artifacts are accompanied by GPG and Sigstore signature files according to the security policy.

Ristretto is a free, open-source Go library for an in-process cache of key-value data, designed for concurrent use, performance and correctness. It keeps data in memory in a single process rather than operating as a distributed cache. TinyLFU admission and SampledLFU eviction are paired to target high hit ratios; applications define item cost, allowing a valuable large item to displace several smaller ones. The project attributes throughput to contention management, batching and eventual consistency. Goroutines can use the cache concurrently with little throughput degradation, according to the project, and optional metrics cover throughput, hit ratios and other statistics. A Set for a new item may be dropped in the Set buffer or admission policy, while updates are guaranteed. Ristretto requires Go 1.21 or later and Go modules. Version 2 supports generics, which the project recommends for new programs. The repository is licensed under Apache License, Version 2.0, and describes the library as production-ready. Its README names Badger and Dgraph as projects using it.