homicki opened a new issue, #16571:
URL: https://github.com/apache/grails-core/issues/16571
### Expected Behavior
In this report, the request session is the Hibernate session that open
session in view (OSIV) binds. The new session is the session that
`withNewSession` opens. The inner transaction is the transaction that
`withTransaction` starts in the new session.
After `withNewSession { withTransaction { … } }` completes, the OSIV-bound
request session remains usable. Subsequent queries and `refresh()` succeed.
### Actual Behaviour
Code runs in the request session without a transaction. It runs and ends a
transaction on the request session. It then calls `withNewSession {
withTransaction { } }`. Inside that block, it reads a lazy association of an
entity that the request session loaded.
After the block, the next statement of the request session fails because its
connection is closed. `GrailsHibernateTemplate` then throws a
`NullPointerException` ("Cannot throw exception because the return value of ...
convertHibernateAccessException(...) is null"). Before the
`NullPointerException`, the log shows the JDBC error. On H2, the error is `The
object is already closed [90007-240]`.
### Steps To Reproduce
1. Clone
https://github.com/homicki/grails8-withnewsession-closed-connection-repro and
run `./gradlew bootRun`.
2. `curl -i http://localhost:8080/repro` returns `500` with the
`NullPointerException` above.
3. `curl -i "http://localhost:8080/repro?lazyLoad=before"` returns `200`.
This control reads the association before the block.
The action runs in the OSIV request session without a transaction.
`BootStrap` seeds one book and its author, and `Book.author` is lazy:
```groovy
Book book = Book.first()
Author.withTransaction { Author.count() } // ends a transaction on the
request session
Book.withNewSession {
Book.withTransaction {
book.author.name // lazy load through the
request session
new Author(name: 'Tenar').save()
}
}
Book.count() // fails: the connection is
closed
```
The reproduction fails when all three of these conditions are true: a
transaction ended on the request session earlier, the first use of the request
session after that transaction is inside the inner transaction, and the inner
block uses `withNewSession`. In the tested variants, `withNewTransaction` alone
succeeds, and loading the association before or after the block also succeeds.
Proposed fix: before executeWithNewSession unbinds the request session, make
an open, disconnected request session get its own connection. I have this fix
with a spec that fails without it and passes with it, written with AI
assistance. If the team agrees with this approach, I can submit it as a pull
request.
### Environment Information
- Grails 8.0.x
- Hibernate ORM 7.4
- Spring Framework 7.0
- MariaDB 10.11 and MySQL 8.4
- Groovy 5.1
- JDK 25
### Example Application
https://github.com/homicki/grails8-withnewsession-closed-connection-repro
### Version
8.0.0
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