What it is
Ehcache and Caffeine are Java caching libraries that improve application performance by storing frequently accessed data in memory, reducing expensive database or API calls. They support in-memory and optionally persistent caching with flexible eviction and expiration policies.
These libraries allow you to store key-value pairs in a cache with expiration, size limits, eviction policies, and optional persistence. Caffeine is highly optimized for low-latency, high-throughput caching, while Ehcache supports more enterprise features including clustering and JMX monitoring.
Installation
Ehcache:
<dependency>
<groupId>org.ehcache</groupId>
<artifactId>ehcache</artifactId>
<version>3.11.9</version>
</dependency>
Caffeine:
<dependency>
<groupId>com.github.ben-manes.caffeine</groupId>
<artifactId>caffeine</artifactId>
<version>3.1.8</version>
</dependency>Getting started
The smallest useful thing you can do with it, and what each part means.
import com.github.benmanes.caffeine.cache.Cache;
import com.github.benmanes.caffeine.cache.Caffeine;
Cache<String, String> cache = Caffeine.newBuilder()
.maximumSize(100)
.expireAfterWrite(10, java.util.concurrent.TimeUnit.MINUTES)
.build();
cache.put("key1", "value1");
String value = cache.getIfPresent("key1");
System.out.println(value);import org.ehcache.Cache;
import org.ehcache.CacheManager;
import org.ehcache.config.builders.*;
CacheManager cacheManager = CacheManagerBuilder.newCacheManagerBuilder().build(true);
Cache<String, String> cache = cacheManager.createCache("myCache",
CacheConfigurationBuilder.newCacheConfigurationBuilder(String.class, String.class,
ResourcePoolsBuilder.heap(100)));
cache.put("key1", "value1");
System.out.println(cache.get("key1"));
cacheManager.close();Advanced usage
Where the library earns its place over a simpler alternative.
Cache<String, String> cache = Caffeine.newBuilder()
.maximumSize(100)
.build(key -> "Value for " + key);
System.out.println(cache.get("key1"));// Configure Ehcache XML for disk persistence
// Allows cache to survive application restarts// Caffeine supports LRU, LFU, and W-TinyLFU eviction policies.
// Ehcache supports LRU, LFU, FIFO and custom policies.System.out.println(cache.stats()); // Caffeine
// Ehcache provides JMX beans for monitoring hits, misses, evictionsErrors and fixes
The failures you are most likely to hit, and what actually resolves them.
- NullPointerException
- Occurs when null keys or values are inserted. Ensure keys and values are non-null.
- CacheMiss
- In Caffeine, `getIfPresent()` returns null if absent. Use `get(key, mappingFunction)` for automatic loading.
- OutOfMemoryError
- Occurs if cache grows without bounds. Define size limits and expiration policies.
Best practices
- Use caches for frequently accessed, immutable or semi-static data.
- Define reasonable size limits and expiration policies to avoid memory issues.
- Monitor cache hit/miss ratios to tune performance.
- For distributed systems, consider clustered cache options (Ehcache Terracotta, Redis integration).
- Avoid caching sensitive data in plaintext unless encrypted.
Background
Why it exists, and what it was reacting to.
Caching is a key technique to optimize performance and scalability. Ehcache, created in 2003, is a mature and widely-used caching library that supports in-memory, disk, and distributed caching. Caffeine, developed later, provides a high-performance, in-memory cache with efficient algorithms like W-TinyLFU for eviction. Both libraries are used in enterprise Java applications to accelerate data access, reduce latency, and manage load efficiently.