When using Ehcache’s ARC (Automatic Resource Control) on a cache acting as the Hibernate cache, these kinds of warning will likely appear:
WARN [pool-1-thread-1] [ehcache.pool.impl.DefaultSizeOfEngine] sizeOf The configured limit of 100 object references was reached while attempting to calculate the size of the object graph. This can be avoided by adding stop points with @IgnoreSizeOf annotations. Since the CacheManger or Cache elements maxDepthExceededBehavior is set to “abort”, the sizing operation has stopped and the reported cache size is not accurate. If performance degradation is NOT an issue at the configured limit, raise the limit value using the CacheManager or Cache elements maxDepth attribute. For more information, see the Ehcache configuration documentation.
To fix this problem, you need to tell ARC what parts of Hibernate objects shouldn’t be counted when calculating object sizes so ARC doesn’t get into an infinite loop (when it hits circular references) or try to calculate the size of the entire Hibernate object graph.
One way to solve this problem is to use ehcache-sizeofengine-hibernate. To do so, simply add the jar to your application’s class path and it will be automatically discovered and used by Ehcache. However, since ehcache-sizeofengine-hibernate isn’t in Maven Central, or any publicly accessible Maven repository, it’s not really useful. I requested that it be published to Central a while ago, but the project seems to be unmaintained – so a more maintainable way to solve this problem is required.
A system property needs to be set pointing to a file that lists the classes and fields that should be ignored by ARC. In my Spring @Configuation class for configuring ehcache, I have this block:
static { System.setProperty(net.sf.ehcache.pool.impl.DefaultSizeOfEngine.USER_FILTER_RESOURCE, "net.sf.ehcache.sizeof.filter.properties"); }
But you can really do this anywhere (including simply adding “-Dnet.sf.ehcache.sizeof.filter=net.sf.ehcache.sizeof.filter.properties” to the Java command line).
Next, create a file named “net.sf.ehcache.sizeof.filter.properties” in the classpath (in a Maven project, the src/main/resources directory makes sense) with these contents:
org.hibernate.Session org.hibernate.internal.SessionImpl org.hibernate.engine.spi.sessionimplementor org.hibernate.cache.spi.QueryKey.positionalParameterTypes org.hibernate.proxy.AbstractLazyInitializer.entityName org.hibernate.proxy.pojo.BasicLazyInitializer.persistentClass org.hibernate.proxy.pojo.BasicLazyInitializer.getIdentifierMethod org.hibernate.proxy.pojo.BasicLazyInitializer.setIdentifierMethod org.hibernate.proxy.pojo.BasicLazyInitializer.componentIdType org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer org.hibernate.engine.spi.TypedValue.type
