I am having an issue with calling session.getEntityName(obj) where a ConcurrentModificationException is thrown. This is occuring in some web application code where I am trying to save the objectId and entity name so that I can load the object again later if needed.

The process is basically:

# load object from hibernate
# call session.getEntityName(...) on the same session it was loaded from.

It is probably important to note that this same code executed in a junit test case works fine without the exception. When running under jetty I get the exception every time. I realize the error is likely to be in my web application setup and how it differs from my test setup but I would like some pointers on where I should start looking for issues as I can't think of what would cause this behavior.


Hibernate version:
3.2

Mapping documents:
<hibernate-mapping auto-import="true" package="com.pinklady.profile">

<class name="MyProfile" table="Profile">
<id name="id" column="userId">
<generator class="foreign">
<param name="property">user</param>
</generator>
</id>
<one-to-one name="user" constrained="true" />

<property name="firstName" not-null="false" unique="false" type="string" length="55" />
<property name="lastName" not-null="false" unique="false" type="string" length="55" />

<array name="urls" table="ProfileUrls">
<key column="userId" />
<index column="ndx" />
<element column="url" type="string" />
</array>

<list name="photos" access="field" cascade="all">
<key column="profileId" not-null="true" />
<index column="ndx" />
<one-to-many class="com.pinklady.Photo" />
</list>
</class>

</hibernate-mapping>

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

Object object = session.load(MyProfile.class, 1234);
String entityName = session.getEntityName(object);

Full stack trace of any exception that occurs:

java.util.ConcurrentModificationException
at org.apache.commons.collections.ReferenceMap$EntryIterator.checkMod(Unknown Source)
at org.apache.commons.collections.ReferenceMap$EntryIterator.hasNext(Unknown Source)
at java.util.AbstractMap.containsValue(AbstractMap.java:108)
at org.hibernate.engine.StatefulPersistenceContext.containsProxy(StatefulPersistenceContext.java:439)
at org.hibernate.impl.SessionImpl.getEntityName(SessionImpl.java:1737)
at com.pinklady.wicket.HibernateObjectModel.setHibernateObject(HibernateObjectModel.java:47)

Name and version of the database you are using:
Postgresql 8.1

The generated SQL (show_sql=true):

n.a

Debug level Hibernate log excerpt:

Doesn't appear to be anything interesting other than the MyProfile object being loaded successfully.


Thanks!

Ryan

Upon further inspection it looks like the object I am using to call getEntityName() (which comes from session.load(MyProfile.class, 1234) is a transient instance of MyProfile. it is strange that session.load(...) would return a transient instance... I am in the process of digging deeper.

The source if my issue revolves around:

<id name="id" column="userId">
<generator class="foreign">
<param name="property">user</param>
</generator>
</id>

in my mapping file. Performing session.load(MyProfile.class, integerId) works great if the profile was saved from that session. If it is saved from a different session it returns an empty proxy (inspecting the debug log output shows no query to the database is performed).

I will start a new thread with the source of the issue, perhaps I am doing this wrong.

I take my previous statement back. Here is a simplified view of what causes the ConcurrentModificationException (CME):



If the commented line in the middle (profile.getFirstName()) remains commented the proxy has not been initialized with data from the database. Calling session.getEntityName(profile) causes the lazy initialization to happen while a collection is being iterated over (and a CME is thrown).

If the line is uncommented getFirstName() causes the lazy initialization to occur. Calling getEntityName(profile) now results in:



This is very strange to me because I just used the session to load that proxy! Why is this happening?

Found the a solution. In my mapping file I changed:



To:



I thought lazy properties were off by default in 3.x? Perhaps I need to look in my configuration to see if anything is setting that for me.

Further is hibernate doing the right thing by not adding a lazy loaded class into its list of proxies?