Ehcache 3.9.2 LFU java configuration

[wm]

Hi,

Using EhCache 3.9.2, I was trying to set the memoryStoreEvictionPolicy to LFU

But, I am not able find any documentation that explains how I can set such configuration in Java or xml for the mentioned version of Ehcache.

Any suggestion on how I can override the default LRU with LFU will be much appreciated.

Thank you

[Chris Dennis]

In Ehcache 3 there is no way of choosing an eviction policy. Each tier within the cache {heap, offheap, disk, cluster} is free to choose the most appropriate eviction policy given it’s implementation. The heap tier operates a biased sampling LRU scheme, the offheap and cluster use an LRU clock. Given that both of these are sampling based and therefore neither strict LRU or LFU, it was decided that configurability here wasn’t worth the implementation cost and that the bulk of users wouldn’t need this fine-grained control.

 

Given the modularity within Ehcache 3 if an LFU policy is a hard requirement, it should be possible for someone to build their own LFU evicting store implementation and plug it in as a third-party provider.

 

Chris

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[wm]

Thank you for your quick response and the details

[wm]

Hello,

Based on the input I get here, I configured ehcache onheap with 200 entries count, and 1MB of maximum object size.

Does this mean that the max heap memory used will be 200MB ? or Should I have to explicitly use MB rather than entries in on heap resource pool configuration?

Thank you.

Wonde

[Chris Dennis]

Could you provide your actual cache configuration (either XML or Java code) to help clarify your question?

 

Thanks,

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[Wondwosen Eshetu]

Hi Chris,

Here is the Java configuration.

ExpiryPolicy policy = ExpirationPolicyBuilder.timeToLiveExpiration(Duraton.ofMinutes(5));

ResourcePools resourcePools = ResourcePoolsBuilder.bewResourcePoolsBuilder()

             .heap(200, EntryUnit.ENTRIES)

CacheConfiguration cacheConfiguration = new CacheConfigurationBuilder( String, String, resourcePools)

        .withSizeOfMaxObjectSize(1, MemoryUnit.MB)

       .withExpiry(policy)

      .build();

CacheManager manager = CacheManagerBuilder.newCacheManagerBuilder()

            .withCache("cache1", cacheConfiguration)

           .build(true)

Thanks and regards,

Wonde

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[Chris Dennis]

The max object size configuration here controls the point at which the size-of engine will abort when sizing an object graph. In your configuration however since the heap tier is count based this condition does essentially nothing. The cache will be be limited to 200 entries. How big each entry is will be entirely up to the application.

Chris

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