Boost Spring Boot Performance with Cache2k: Setup, Benchmarks, and Advanced Config

When discussing Java in-memory cache libraries, the well-known Ehcache and the newer Caffeine are often mentioned, and Spring Boot 2.7 now adds official dependency management and auto-configuration for Cache2k, confirming its recognition by the Spring team.

Cache2k is an open-source, lightweight, high-performance Java memory cache library.

Benchmarks show that its throughput significantly exceeds that of Ehcache3 and Caffeine.

1. How to Use

① Add Dependency

<!-- springboot 2.7 already defines cache2k version globally, no need to specify version -->
<dependency>
    <groupId>org.cache2k</groupId>
    <artifactId>cache2k-spring</artifactId>
</dependency>

② Configure Cache Type

③ Spring Cache Annotation Example

@Cacheable(value = "demo", key = "#key")
public String get(String key) {
    return "success";
}

2. Advanced Configuration

Personalized Parameters

Implement the Cache2kBuilderCustomizer interface to customize cache settings.

public class CustomCache2kBuilderCustomizer implements Cache2kBuilderCustomizer {
    /**
     * Customize the default cache settings.
     *
     * @param builder the builder to customize
     */
    @Override
    public void customize(Cache2kBuilder<?, ?> builder) {
        // custom logic
    }
}

Micrometer Metrics Monitoring

<dependency>
  <groupId>org.cache2k</groupId>
  <artifactId>cache2k-micrometer</artifactId>
</dependency>

Expose key cache statistics that can be integrated with Prometheus.

Cache{database}(size=50003, capacity=50000, get=102876307, miss=1513517, put=0, load=4388352, reload=0, heapHit=101362790, refresh=2874835, refreshFailed=42166, refreshedHit=2102885, loadException=0, suppressedException=0, new=1513517, expire=587294, remove=8156, clear=0, removeByClear=0, evict=868064, timer=3462129, goneSpin=0, hitRate=98.52%, msecs/load=0.425, asyncLoadsStarted=2874835, asyncLoadsInFlight=0, loaderThreadsLimit=8, loaderThreadsMaxActive=8, created=2016-12-02 03:41:34.367, cleared=-, infoCreated=2016-12-02 14:34:34.503, infoCreationDeltaMs=21, collisions=8288, collisionSlots=7355, longestSlot=5, hashQuality=83, noCollisionPercent=83, impl=HeapCache, eviction0(impl=ClockProPlusEviction, chunkSize=11, coldSize=749, hotSize=24252, hotMaxSize=24250, ghostSize=12501, coldHits=11357227, hotHits=38721511, ghostHits=294065, coldRunCnt=444807, coldScanCnt=698524, hotRunCnt=370773, hotScanCnt=2820434), eviction1(impl=ClockProPlusEviction, chunkSize=11, coldSize=778, hotSize=24224, hotMaxSize=24250, ghostSize=12501, coldHits=11775594, hotHits=39508458, ghostHits=283324, coldRunCnt=423258, coldScanCnt=674762, hotRunCnt=357457, hotScanCnt=2689129), evictionRunning=0, keyMutation=0)

Summary

The Cache2k JAR is only about 400 KB and has no additional dependencies, making it suitable for Android projects.

Despite performance comparable to Caffeine, it is less popular in China due to limited local documentation.

References

Cache2k: https://cache2k.org

Benchmarks: https://cache2k.org/benchmarks.html