[hibernate-issues] [Hibernate-JIRA] Commented: (HHH-4808) SessionImpl.initializeCollection() does not release JDBC connection (if outside of a transaction)

[Martin Renner (JIRA)]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-4808?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=35241#action_35241 ] 

Martin Renner commented on HHH-4808:
------------------------------------

The attached program shows the following output:

{code}
INFO  [Test                ] Accessing lazily loaded collection...
DEBUG [ConnectionManager   ] opening JDBC connection
DEBUG [SQL                 ] select person0_.id as id0_0_, person0_.version as version0_0_, person0_.name as name0_0_ from Person pe...
DEBUG [SQL                 ] select pets0_.Person_Id as Person1_1_, pets0_.Pet_Id as Pet2_1_, pet1_.id as id2_0_, pet1_.version ...
INFO  [Test                ] ...done with collection. Should have seen "aggressively releasing JDBC connection".
INFO  [Test                ] 
INFO  [Test                ] Executing a query...
DEBUG [SQL                 ] select person0_.id as id0_, person0_.version as version0_, person0_.name as name0_ from Person person0_
DEBUG [ConnectionManager   ] aggressively releasing JDBC connection
DEBUG [ConnectionManager   ] releasing JDBC connection [ (open PreparedStatements: 0, globally: 0) (open ResultSets: 0, globally: 0)]
INFO  [Test                ] ...done with query. Should have seen "aggressively releasing JDBC connection".
INFO  [Test                ] 
DEBUG [ConnectionManager   ] connection already null in cleanup : no action
{code}

As you can see, the loading of the collection does not release the collection. In contrast, the query does release the connection.

> SessionImpl.initializeCollection() does not release JDBC connection (if outside of a transaction)
> -------------------------------------------------------------------------------------------------
>
>                 Key: HHH-4808
>                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-4808
>             Project: Hibernate Core
>          Issue Type: Bug
>          Components: core
>    Affects Versions: 3.2.7, 3.3.2
>            Reporter: Martin Renner
>            Priority: Critical
>         Attachments: Test.java
>
>
> With {{ConnectionReleaseMode.AFTER_TRANSACTION}} (the default), Hibernate does not release the JDBC connection when resolving a lazily loaded collection, if this happens *outside* of an active transaction.
> First, I will describe, what happens if Hibernate executes a query outside of a transaction. Then I will describe how lazy collection loading behaves differently.
> When the method {{list}} of a query ({{QueryImpl.java}}) is getting called, Hibernate delegates to {{SessionImpl.list()}}. After having loaded the list, {{SessionImpl.list()}} calls {{SessionImpl.afterOperation()}}, which calls {{jdbcContext.afterNontransactionalQuery()}} (as there is no active transaction). This leads to {{ConnectionManager.afterTransaction()}} which releases the JDBC connection. This is exactly what I expect to happen.
> Now to the lazily loaded collection:
> {{Hibernate.initialize(collection)}} and {{person.getPets().size()}} both end up in {{SessionImpl.initializeCollection()}}. This call gets dispatched down to {{Loader.doQueryAndInitializeNonLazyCollections()}} and {{Loader.doQuery()}}. The important fact is, that {{ConnectionManager.afterTransaction()}} never gets called (like in the query-example above).
> The result is, that the JDBC connection is not released.
> IMHO resolving of a lazily loaded collection should behave like executing a query. {{SessionImpl.initializeCollection()}} should call {{SessionImpl.afterOperation()}} in the same way as {{SessionImpl.list()}} is doing this.
> I will attach a small demo application which shows the difference (concerning {{ConnectionManager}}) between queries and collections.

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