Problems with second level cache (EH),
Newly created child object is not added to parent's (which is in second level cache)
collection of child objects.

I am facing problems with second level cache(EH),
I am creating child object using session.save(childObj). After closing the session,
I am opening a new session and retrievig parent object through it. But the collection in
the parent does not contain the child object created in the above step
even though child record is created in the data base.

But I could see delete working perfectly OK. If I delete the child object using
session.delete(childObj), the child object is deleted from it's parent object's collection.

Even though I could solve this problem by adding
the child object to the collection and save the parent, this is not feasible solution for me.
Parent has lot of child object types which are updated in many parts of the application.

Please help solve this issue. I am new to this forum.


Hibernate version: 3.3.1

Mapping documents:

Relevant portions of LevelType.hbm.xml


<class name="LevelType" table="levelTypes" dynamic-update="true">
<cache usage="nonstrict-read-write" region="enterpriseCacheRegion"/>

<id name="id" type="com.rrd.xspace.data.levels.hibernate.HiberLevelTypeID">
<column name="id" length="32"/>
<generator class="com.rrd.xspace.data.levels.hibernate.LevelTypeIDGenerator"></generator>
</id>
..............
................
...............
<set name="levelMetaDataTypes" inverse="true" lazy="false" cascade="all-delete-orphan">
<cache usage="nonstrict-read-write" region="enterpriseCacheRegion"/>
<key column="levelTypeId"/>
<one-to-many not-found="ignore" class="com.rrd.xspace.data.levels.metadata.LevelMetaDataType"/>
</set>

</class>

Relevant portions of LevelMeataDataType.hbm.xml


<class name="LevelMetaDataType" table="levelMetaDataTypes" dynamic-update="true">
<cache usage="nonstrict-read-write" region="enterpriseCacheRegion"/>
<id name="id" type="com.rrd.xspace.data.levels.hibernate.HiberLevelMetaDataTypeID">
<column name="id" length="32"/>
<generator class="com.rrd.xspace.data.levels.hibernate.LevelMetaDataTypeIDGenerator"></generator>
</id>
.................
............

<many-to-one name="levelType" column="levelTypeId" lazy="proxy" fetch="select"/>


</class>


ehcache.xml


<ehcache xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="ehcache.xsd">
<diskStore path="java.io.tmpdir" />

<cacheManagerPeerProviderFactory
class="net.sf.ehcache.distribution.RMICacheManagerPeerProviderFactory"
properties="peerDiscovery=manual,rmiUrls=//localhost:40001/enterpriseCacheRegion"/>

<cacheManagerPeerListenerFactory
class="net.sf.ehcache.distribution.RMICacheManagerPeerListenerFactory"
properties="hostName=localhost, port=40002,socketTimeoutMillis=1200000" />

<cache name="enterpriseCacheRegion" maxElementsInMemory="1000"
eternal="true" timeToIdleSeconds="1200" timeToLiveSeconds="1200"
overflowToDisk="false" diskPersistent="false"
diskExpiryThreadIntervalSeconds="1200"
memoryStoreEvictionPolicy="LRU">

<cacheEventListenerFactory
class="net.sf.ehcache.distribution.RMICacheReplicatorFactory"
properties="replicateAsynchronously=true,
asynchronousReplicationIntervalMillis=20,
replicatePuts=true,
replicateUpdates=true,
replicateUpdatesViaCopy=false,
replicateRemovals=true " />
</cache>

<defaultCache maxElementsInMemory="1000" eternal="true"
timeToIdleSeconds="1200" timeToLiveSeconds="1200" overflowToDisk="false"
diskPersistent="false" diskExpiryThreadIntervalSeconds="1200"
memoryStoreEvictionPolicy="LRU" />

</ehcache>



Code between sessionFactory.openSession() and session.close():

Session session = HibernateSessionFactory.getSession(); // opens new session
session.save(levelMetaDataTypeObj); // Child Object which has
//parent object reference
session.flush();
session.close();

// the below code is in another method call

Session session = HibernateSessionFactory.getSession(); // opens new session

Criteria criteria = session.createCriteria(LevelType.class);
criteria.add(Restrictions.eq("id", id));
LevelType type = (LevelType) criteria.uniqueResult();// LevelType
//is parent

Set levelMetaDataTypes = type.getLevelMetaDataTypes(); // this
//set does not contain child object created above
session.close();


Debug level Hibernate log excerpt:

Hi,

Did I not provide enough information to make my issue understood?
Some one would have already faced similar problem. Please help.

Regards
ganesh.

I had a problem very very similar to yours. My guess is that it's a bug in Hibernate. However, I did find a solution: adding
to the many-to-one did the trick for me.

In your case that would be:

Thanks a lot for your reply. I will try this and let you know.
Mean while I would like to tell something interesting about caching that I found.

The way hibernate session interacts with the second level cache can be controlled by setting the cache mode on session
(session.setCacheMode()). By looking at the documentation of CacheMode.java,
I understood that a new item will be put in the second level cache only
while retreiving it from database. Session does not put the item in second level cache when you create new record using session.save(). I have verified this by creating a new object using session.save()
in all 4 different cache modes and at the same time observed the number of items in the Second level cache. The number of items
would never increase until I retrieve the just created object using session.get().

The suggested solution has worked.
Thanks a lot gjvoosten.

You're welcome!

On a related note: I have done more testing with my own application, and found that there are several problems with second-level caching, unfortunately. A working application with hibernate.cache.use_second_level_cache=false exhibits the following when hibernate.cache.use_second_level_cache=true; apart from the one you mentioned I experienced:

- LazyInitializationExceptions that only appear when second-level caching is enabled
- a child is added to a parent's collection in the database, but the collection in the second-level cache is not updated
- a child is added to a parent's collection in the database twice, but only once in the second-level cache
- a new child object is added to a parent's collection, and upon persisting the child I get a Hibernate exception stating that the child instance is transient and I need to persist it first...

All these are with collection caching; I have now completely abandoned second-level caching of collections.

With second-level caching of entities I have found no problems. Well, not yet anyway. Second-level caching of (named) queries also has caused me no problems so far.

Version details: this is with hibernate-3.2.6.ga, hibernate-entitymanager-3.3.2.GA and ehcache-1.5.0; my model is in .hbm.xml files, with Java classes generated by hibernate3-maven-plugin:hbm2java.

This seems to be a new problem. We have been using 3.1.2GA for a couple years with either JBoss Cache or Coherence as the second-level cache.

I decided to try out the 3.3.1 to see if it was worth upgrading since this was a good time in our product's lifecycle.

The only changes I made were to specify the Oracle10gDialect and specify the new JBoss Cache.

I am seeing similar problems to what you are seeing, and have not found any solution. I agree that it appears that the cache is not getting updated as we would expect. I save the parent assuming the children will get updated which worked well in the past.

From what I can tell the database seems fine, but the collection is not getting updated consistently in the cache. It is hard to determine what is going on, because I have not been able to come up with a pattern for when it works or doesn't.

I am wondering if a workaround is to evict the collection from the second-level cache when I change it.

I am a bit leary upgrading, because I would have expected improvements and not new problems for what seems like something pretty basic.

This seems to be a new problem. We have been using 3.1.2GA for a couple years with either JBoss Cache or Coherence as the second-level cache.

I decided to try out the 3.3.1 to see if it was worth upgrading since this was a good time in our product's lifecycle.

The only changes I made were to specify the Oracle10gDialect and specify the new JBoss Cache.

I am seeing similar problems to what you are seeing, and have not found any solution. I agree that it appears that the cache is not getting updated as we would expect. I save the parent assuming the children will get updated which worked well in the past.

From what I can tell the database seems fine, but the collection is not getting updated consistently in the cache. It is hard to determine what is going on, because I have not been able to come up with a pattern for when it works or doesn't.

I am wondering if a workaround is to evict the collection from the second-level cache when I change it.

I am a bit leary upgrading, because I would have expected improvements and not new problems for what seems like something pretty basic.

This seems to be a new problem. We have been using 3.1.2GA for a couple years with either JBoss Cache or Coherence as the second-level cache.

I decided to try out the 3.3.1 to see if it was worth upgrading since this was a good time in our product's lifecycle.

The only changes I made were to specify the Oracle10gDialect and specify the new JBoss Cache.

I am seeing similar problems to what you are seeing, and have not found any solution. I agree that it appears that the cache is not getting updated as we would expect. I save the parent assuming the children will get updated which worked well in the past.

From what I can tell the database seems fine, but the collection is not getting updated consistently in the cache. It is hard to determine what is going on, because I have not been able to come up with a pattern for when it works or doesn't.

I am wondering if a workaround is to evict the collection from the second-level cache when I change it.

I am a bit leary upgrading, because I would have expected improvements and not new problems for what seems like something pretty basic.