即使在timeToLiveSeconds和/或timeToIdleSeconds之后，Ehcache也不会从缓存中删除元素

Question

需要帮助。 我正在开发一个项目，当它在一段时间内没有使用时我必须删除元素（键）。我尝试使用timeToLiveSeconds和timeToIdleSeconds作为60秒。还尝试了只有timeToLiveSeconds = 60并且只有timeToIdleSeconds = 60。但我仍然在缓存中看到该元素。

fyi：我有一些代码可以在屏幕上显示所有缓存的元素。

屏幕截图0：在为我的操作调用REST服务之前。期望：元素不应出现在缓存网页中 - 按预期工作

屏幕截图1：调用REST服务后执行我的操作。期望：请参阅网页中缓存列表中的元素 - 按预期工作

现在空闲60秒（不要调用REST服务，意味着元素不使用60秒）

屏幕截图2：刷新缓存网页。期望：元素不应出现在缓存网页中 - 不按预期工作

• 元素表示AF2TDU2001
• 我们正在使用ehcache 2.5.2

这是我的代码：

/**
     * 
     * @param cacheName
     * @param diskPersistent
     */
    private static void addCache(String cacheName, boolean diskPersistent) {
        /*
            @param name - the name of the cache. Note that "default" is a reserved name for the defaultCache.
            @param maxElementsInMemory - the maximum number of elements in memory, before they are evicted (0 == no limit)
            @param memoryStoreEvictionPolicy - one of LRU, LFU and FIFO. Optionally null, in which case it will be set to LRU.
            @param overflowToDisk - whether to use the disk store
            @param diskStorePath - this parameter is ignored. CacheManager sets it using setter injection.
            @param eternal - whether the elements in the cache are eternal, i.e. never expire
            @param timeToLiveSeconds - the default amount of time to live for an element from its creation date
            @param timeToIdleSeconds - the default amount of time to live for an element from its last accessed or modified date
            @param diskPersistent - whether to persist the cache to disk between JVM restarts
            @param diskExpiryThreadIntervalSeconds - how often to run the disk store expiry thread. A large number of 120 seconds plus is @param recommended
            @param registeredEventListeners - a notification service. Optionally null, in which case a new one with no registered listeners will @param be created.
            @param bootstrapCacheLoader - the BootstrapCacheLoader to use to populate the cache when it is first initialised. Null if none is @param required.
            @param maxElementsOnDisk - the maximum number of Elements to allow on the disk. 0 means unlimited.
            @param diskSpoolBufferSizeMB - the amount of memory to allocate the write buffer for puts to the DiskStore.
         */
        Cache cache = new Cache(cacheName,
                10000, // maxElementsInMemory
                MemoryStoreEvictionPolicy.LRU,  // memoryStoreEvictionPolicy
                false, // overflowToDisk
                diskStorePath,
                true,  // eternal
                60,  // timeToLiveSeconds
                60,  // timeToIdleSeconds
                false, // diskPersistent
                1,  // diskExpiryThreadIntervalSeconds
                null,
                null,
                0,  // bootstrapCacheLoader
                0,  // maxElementsOnDisk
                false);
        cacheManager.addCache(cache);
    }

Answer 1

请注意，当永恒属性设置为“ true”时，它将覆盖timeToLive和timeToIdle，因此不会发生过期。 （https://www.ehcache.org/documentation/2.8/configuration/configuration.html） 在您的配置中，参数“永恒”具有“真实”价值。

Answer 2

Ehcache只会在访问或驱逐时删除过期的元素。如果你根本不与缓存进行交互，那么就不会出现急切的过期 - 就像后台线程一样 -

这意味着：

cache.put(new Element(key, value)); // Assume cache TTL is 60 seconds
Thread.sleep(30000);
assert cache.getSize() == 1; // as there is one mapping
cache.get(key); // Returns the mapping as it is not expired
Thread.sleep(40000); // No interactions with the cache, the entry is still in there.
cache.put(new Element(otherKey, otherValue)); // Would remove the other entry if max size is 1
assert cache.getSize() == 2; // assuming the cache can hold more than one mapping
cache.get(key); // Would return null because the value is expired and thus removed upon access.
assert cache.getSize() == 1; // because the previous get did finally remove the expired mapping.