I add objects to a set and then tries to iterate it.

A call to throws this one:

java.util.ConcurrentModificationException
at java.util.HashMap$HashIterator.nextEntry(HashMap.java:782)
at java.util.HashMap$KeyIterator.next(HashMap.java:818)
at net.sf.hibernate.collection.PersistentCollection$IteratorProxy.next(PersistentCollection.java:441)



I'm using 2.1.2 and lazy sets.

Anyone?

I do not use threads, by the way....

It can be caused by bug in cache / "disconnected" session, or
by objects stored in httpsession/servletContext.

"ConcurrentModificationException" always means "Concurrent Modification" :)

Did you ever find a fix for this problem? I am getting a similar problem attempting to do deletes. My relationship basically looks like this.

GrandParent -> Parent -> Child.

I have cascade="delete-all-orphan" on each collection and inverse="true".
I also have cascade="none" for the "toParent" relationships.

My stack trace looks like this.

at java.util.AbstractList$Itr.checkForComodification(AbstractList.java:444)
at java.util.AbstractList$Itr.next(AbstractList.java:417)
at net.sf.hibernate.collection.PersistentCollection$IteratorProxy.next(PersistentCollection.java:441)
at net.sf.hibernate.engine.Cascades.cascadeCollection(Cascades.java:526)
at net.sf.hibernate.engine.Cascades.cascade(Cascades.java:452)
at net.sf.hibernate.engine.Cascades.cascade(Cascades.java:503)
at net.sf.hibernate.engine.Cascades.cascade(Cascades.java:482)
at net.sf.hibernate.impl.SessionImpl.doDelete(SessionImpl.java:1209)
at net.sf.hibernate.impl.SessionImpl.delete(SessionImpl.java:1146)

you mean?
how do you manage your hibernate Sessions?

At the beginning we considered the session as the application cache, it isn't!!!
Consider hibernate Session as a business unit cache, the cache is EHCache for example.

i this can help you....