java - 番石榴CacheBuilder性能

Question

以下微基准测试使用 Guava CacheBuilder。它的执行速度比 ConcurrentHashMap 慢 1 倍。我是否正确使用了 CacheBuilder？

    final Cache c = CacheBuilder.newBuilder().concurrencyLevel(10).maximumSize(100).build();
    int num = 10;
    final java.util.concurrent.CountDownLatch startSignal = new java.util.concurrent.CountDownLatch(1);
    final java.util.concurrent.CountDownLatch doneSignal = new java.util.concurrent.CountDownLatch(num);
    int j = 0;
    final Long[] pairs = new Long[] { new Long(5),
            new Long(324235342L), new Long(3242385842L), new Long(8463242363642L),
            new Long(3244532342L), new Long(54654L), new Long(7332742342L),
            new Long(32425345342L), new Long(32453662342L), new Long(63573242342L) };
    Object state = new Object();

    for (Long p : pairs) {
        c.put(p, state);
    }
    Thread [] threads = new Thread[num];
    for (int k = 0 ; k < num ; ++k) {
        final int z = k;
        threads[k] = new Thread(new Runnable() {
            int i = z;
            @Override
            public void run() {
                try {
                    startSignal.await();
                    for (int j = 0 ; j < 100000 ; ++j) {
                        c.getIfPresent(pairs[z]);
                    }
                    doneSignal.countDown();
                } catch (Exception e) {
                    e.printStackTrace();
                }

            }
        });
    }
    for (Thread t : threads) {
        t.start();
    }
    startSignal.countDown();
    c.getIfPresent(pairs[1]);
    long t = System.currentTimeMillis();
    doneSignal.await();
    System.out.println("done in " + (System.currentTimeMillis() - t));

ConcurrentHashMap 给了我 9 毫秒。CacheBuilder 给了我 90 毫秒。这是在循环相同的代码几分钟之后。