Repro.java

// Run with:
java -cp . -XX:+UseConcMarkSweepGC -XX:+UseParNewGC -XX:ParallelCMSThreads=24 -XX:+PrintGCDetails -XX:+PrintGCDateStamps Repro

import java.util.Map;
import java.util.Random;
import java.util.ArrayList;
import java.util.Collection;
import java.util.LinkedHashMap;

class Repro {
  public static void main(String[] args) {
    LRUCache<String, String> cache = new LRUCache<String, String>(10000000);
    Random random = new Random();

    while (true) {
      cache.put("This is a string." + random.nextInt(), "This is a string." + random.nextInt());
    }
  }  

  // This naive LRUCache aped from http://www.source-code.biz/snippets/java/6.htm
  public static class LRUCache<K,V> {
    private static final float   hashTableLoadFactor = 0.75f;
    private LinkedHashMap<K,V>   map;
    private int                  cacheSize;

    public LRUCache (int cacheSize) {
       this.cacheSize = cacheSize;
       int hashTableCapacity = (int)Math.ceil(cacheSize / hashTableLoadFactor) + 1;

       map = new LinkedHashMap<K,V>(hashTableCapacity, hashTableLoadFactor, true) {
          private static final long serialVersionUID = 1;
          @Override protected boolean removeEldestEntry (Map.Entry<K,V> eldest) {
             return size() > LRUCache.this.cacheSize;
          }
       };
    }

    public synchronized V get (K key) { return map.get(key); }
    public synchronized void put (K key, V value) { map.put (key, value); }
    public synchronized void clear() { map.clear(); }
    public synchronized int usedEntries() { return map.size(); }
    public synchronized Collection<Map.Entry<K,V>> getAll() { return new ArrayList<Map.Entry<K,V>>(map.entrySet()); }
  }
}