Question

I am using the Google Guava CacheBuilder to create a Cache instance. My code looks something like the following:

return CacheBuilder.newBuilder()
            .initialCapacity(initialCapacity)
            .expireAfterAccess(expirationInterval, TimeUnit.SECONDS)
            .removalListener(LOGGING_AUTOEVICTION_ONLY_REMOVAL_LISTENER)
            .build();

My removal listener is, as the name implies:

private static final RemovalListener<MyKey, MyRecord>  LOGGING_AUTOEVICTION_ONLY_REMOVAL_LISTENER
        = new RemovalListener<MyKey, MyRecord>() {
            @Override
            public void onRemoval(RemovalNotification<MyKey, MyRecord objectObjectRemovalNotification) {
                if (objectObjectRemovalNotification.wasEvicted()) {
                    log.debug("Entry evicted from cache: {} - Reason: {}", objectObjectRemovalNotification, objectObjectRemovalNotification.getCause());
                }
            }
        };

Finally, I only ever get entries to my cache, using get(K key, Callable<? extends V> valueLoader)

Here’s the problem: with the above code, I am seeing the following log output:

19:08:03.287 DEBUG [MyCache] - Entry evicted from cache: MyKey[123]=MyRecord@43ee148b - Reason: SIZE

Why are records being evicted from my cache when I didn’t use maximumSize() in the CacheBuilder invocation? I suspect it has something to do with “weight.” If so, what do I need to know about maxWeight() to not have cache entries evicted before the expiration time?

NOTE I’m aware of Caches Explained on the Google Guava site.

Answer 1

Is it possible that your expirationInterval is accidentally equal to zero? As expireAfterAccess documents, “When duration is zero, this method hands off to maximumSize(0).”