Question

我正在使用Ehcache来缓存在我的应用程序中加载非常昂贵的对象。在启动时，我会缓存所有需要的对象，并且每天通过一个单独的进程刷新一次。

然而，似乎在我将对象添加到缓存后不久，它们就消失了。没有任何东西被报告为被驱逐，但由于某种原因，对象不会在缓存中持久存在。当我运行ObjectLoader.loadCache（）时，这是我收到的输出：

2012-09-01 17:25:37,121 [main] DEBUG ObjectLoader.getObject():65 - ************************************
2012-09-01 17:25:37,121 [main] DEBUG ObjectLoader.getObject():66 - Number of objects in cache: 0
2012-09-01 17:25:37,121 [main] DEBUG ObjectLoader.getObject():72 - Object not in cache | 501
2012-09-01 17:26:17,271 [main] DEBUG ObjectLoader.getObject():80 - Number of objects in cache: 1
2012-09-01 17:26:17,271 [main] DEBUG ObjectLoader.getObject():81 - Number of objects evicted from cache: 0
2012-09-01 17:26:17,274 [main] DEBUG ObjectLoader.getObject():83 - Object key found: 501
2012-09-01 17:26:17,274 [main] DEBUG ObjectLoader.getObject():65 - ************************************
2012-09-01 17:26:17,274 [main] DEBUG ObjectLoader.getObject():66 - Number of objects in cache: 1
2012-09-01 17:26:17,274 [main] DEBUG ObjectLoader.getObject():72 - Object not in cache | 518
2012-09-01 17:26:35,894 [main] DEBUG ObjectLoader.getObject():80 - Number of objects in cache: 1
2012-09-01 17:26:35,895 [main] DEBUG ObjectLoader.getObject():81 - Number of objects evicted from cache: 0
2012-09-01 17:26:35,895 [main] DEBUG ObjectLoader.getObject():83 - Object key found: 518
2012-09-01 17:26:35,895 [main] DEBUG ObjectLoader.getObject():65 - ************************************
2012-09-01 17:26:35,895 [main] DEBUG ObjectLoader.getObject():66 - Number of objects in cache: 1
2012-09-01 17:26:35,895 [main] DEBUG ObjectLoader.getObject():72 - Object not in cache | 516
2012-09-01 17:27:31,997 [main] DEBUG ObjectLoader.getObject():80 - Number of objects in cache: 1
2012-09-01 17:27:31,998 [main] DEBUG ObjectLoader.getObject():81 - Number of objects evicted from cache: 0
2012-09-01 17:27:31,998 [main] DEBUG ObjectLoader.getObject():83 - Object key found: 516
2012-09-01 17:27:31,998 [main] DEBUG ObjectLoader.getObject():65 - ************************************
2012-09-01 17:27:31,998 [main] DEBUG ObjectLoader.getObject():66 - Number of objects in cache: 1
2012-09-01 17:27:31,998 [main] DEBUG ObjectLoader.getObject():72 - Object not in cache | 515
2012-09-01 17:28:20,343 [main] DEBUG ObjectLoader.getObject():80 - Number of objects in cache: 1
2012-09-01 17:28:20,343 [main] DEBUG ObjectLoader.getObject():81 - Number of objects evicted from cache: 0
2012-09-01 17:28:20,344 [main] DEBUG ObjectLoader.getObject():83 - Object key found: 515
2012-09-01 17:28:20,344 [main] DEBUG ObjectLoader.getObject():65 - ************************************
2012-09-01 17:28:20,344 [main] DEBUG ObjectLoader.getObject():66 - Number of objects in cache: 1
2012-09-01 17:28:20,344 [main] DEBUG ObjectLoader.getObject():72 - Object not in cache | 525
2012-09-01 17:29:05,616 [main] DEBUG ObjectLoader.getObject():80 - Number of objects in cache: 1
2012-09-01 17:29:05,617 [main] DEBUG ObjectLoader.getObject():81 - Number of objects evicted from cache: 0
2012-09-01 17:29:05,617 [main] DEBUG ObjectLoader.getObject():83 - Object key found: 525
2012-09-01 17:29:05,617 [main] DEBUG ObjectLoader.getObject():65 - ************************************
2012-09-01 17:29:05,617 [main] DEBUG ObjectLoader.getObject():66 - Number of objects in cache: 1
2012-09-01 17:29:05,618 [main] DEBUG ObjectLoader.getObject():72 - Object not in cache | 512
2012-09-01 17:29:38,790 [main] DEBUG ObjectLoader.getObject():80 - Number of objects in cache: 1
2012-09-01 17:29:38,790 [main] DEBUG ObjectLoader.getObject():81 - Number of objects evicted from cache: 0
2012-09-01 17:29:38,790 [main] DEBUG ObjectLoader.getObject():83 - Object key found: 512

我是否配置了错误的ehcache或我的代码中是否有错误？任何帮助，将不胜感激。谢谢。

我正在使用spring 3.1.0，ehcache-spring-annotations 1.1.2和ehcache 2.4.2

ObjectCacheFacade.java

@Component()
public class ObjectCacheFacade {
    private static final String CACHE_KEY = "myObjectCache";

    @Resource
    private CacheManager cacheManager;
    private Cache cache;

    public ObjectCacheFacade() {
        cacheManager = CacheManager.getInstance();
        this.cache = cacheManager.getCache(CACHE_KEY);
    }

    public Object getObjectFromCache(String objectId) {
        Object result = null;
        Element element = cache.get(objectId);

        if (element != null && element.getValue() != null) {
            result = element.getObjectValue();
        } 

        return result;
    }

    public void putObjectIntoCache(String objectId, Object object) {
        Element element = new Element(objectId, object);
        cache.put(element);
    }

    public int getSize() {
        return cache.getSize();
    }

    public void removeObjectFromCache(String objectId) {
        cache.remove(objectId);
    }

    public void flushCache() {
        cache.removeAll();
    }

    public Cache getCache() {
        return cache;
    }
}

ObjectLoader.java

@Service
public class ObjectLoader {
    private static final Logger log = Logger.getLogger(ObjectLoader.class);

    @Resource
    protected ObjectDao objectDao;
    @Resource
    protected ObjectCacheFacade objectCache;

    public void loadCache() {
        List<String> objectIds = objectDao.getObjectIds();

        for (String objectId : objectIds) {
            loadObject(objectId);
        }
    }

    public Object getObject(String objectId) {
        log.debug("************************************");
        log.debug("Number of objects in cache: " + objectCache.getSize());

        Object object = objectCache.getObjectFromCache(objectId);

        if (object == null) {
            log.debug("Object not in cache | " + objectId);
            object = objectDao.getObject(objectId);

            if (object != null) {
                objectCache.putObjectIntoCache(objectId, object);

                log.debug("Number of objects in cache: " + objectCache.getSize());
                log.debug("Number of objects evicted from cache: " + objectCache.getCache().getCacheEventNotificationService().getElementsEvictedCounter());
                for (Object key : objectCache.getCache().getKeys()) {
                    log.debug("Object key found: " + key);
                }
            } 
        } 

        return object;
    }
}

ehcache.xml中

<ehcache>
    <diskStore path="java.io.tmpdir"/>

    <defaultCache
        maxElementsInMemory="1000"
        eternal="false"
        timeToIdleSeconds="60"
        timeToLiveSeconds="300"
        overflowToDisk="false"
        memoryStoreEvictionPolicy="LRU"
       />

    <cache
        name="myObjectCache"
        maxElementsInMemory="1000"
        eternal="true"
        timeToIdleSeconds="0"
        timeToLiveSeconds="0"
        overflowToDisk="false"
        diskPersistent="true"
        memoryStoreEvictionPolicy="LRU"
       />

</ehcache>

的applicationContext.xml

<bean id="cacheManager" class="org.springframework.cache.ehcache.EhCacheManagerFactoryBean" />

Answer 1

由于diskPersistent设置为true Ehcache在将对象添加到缓存后尝试将对象写入磁盘。但是，主缓存对象中的一个嵌套对象未实现Serializable，因此它在磁盘写入时抛出异常，然后从缓存中逐出该对象。由于没有被memoryStoreEvictionPolicy驱逐，因此这种驱逐没有出现在缓存统计中。

这应该是一个非常容易找到的错误，但该项目不包含slf4j-log4j12库，因此异常被吞下而不是写入日志。一旦正确处理了日志记录，就会立即明白问题所在。

哦，好吧，生活和学习我猜...

Ehcache失去了对象

1 个答案: