We are heavily using UserType(s) and noticed that Hibernates creates multiple instances of the same UserType.
To be more accurate, it creates a new instance for every mapped property that uses it.

Some of our UserType(s) are quite heavy (construction time and memory consumption). I'm wondering if Hibernate could create a single instance and reuse it every time it needs it - as it already does for regular types...

Any comment ?

Note: using Hibernate 2.1.1

Note2: that same behavior is observed for CompositeUserType(s)

Can you post it to JIRA for good tracking ?

JIRA entry HB-644 created (http://opensource.atlassian.com/projects/hibernate/secure/ViewIssue.jspa?key=HB-644)

Do you want me to submit a patch or is this part of the code too "sensitive" ?

Feel free to attatch a patch, Gavin will surely detect if it breaks anything :)

First question
I spotted two places in the code where UserTypes are created:
- in Hibernate.custom()
- in TypeFactory.heuristicType()

The TypeFactory already makes reference to Hibernate.* methods where the singleton for native types are defined.

My question now is where should I create the pool of UserType instances ?
According to the names, I would do it in the TypeFactory. But doing so will introduce circular dependencies between Hibernate and TypeFactory...

It seems the best place is therefore in Hibernate (class) itself.
Any opinion ?

Second question
The PersistentEnum(s) suffer from the same 'problem'.
Wondering if we could pool them as well ?
Are there any other types like those ?

I've posted these questions as comments to the JIRA entry.
I don't think the Beginners forum is the best place to discuss them.
I will post a summary in the forum once the JIRA entry is closed.

I am -1 on this change; please see my comments in the JIRA issue.