[hibernate-issues] [Hibernate-JIRA] Commented: (HHH-2631) Leaking PreparedStatement and ResultSet via CollectionLoadContext instances maintained in Map collectionLoadContexts in LoadContexts

[Steve Ebersole (JIRA)]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-2631?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_27171 ] 

Steve Ebersole commented on HHH-2631:
-------------------------------------

Actually on second thought, I decided to go ahead with Gail's approach for this currently.  Since I plan on this part of the code changing drastically in the near future, I'm not gonna expand a lot of effort tracking down all the contexts from which CollectionLoadContexts actually get created (I know the places from which they *should* get created...).

Anyway, I have attached my patch against the current 3.2 branch.  It is also checked in to both the 3.2 branch and trunk.

> Leaking PreparedStatement and ResultSet via CollectionLoadContext instances maintained in Map collectionLoadContexts in LoadContexts
> ------------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: HHH-2631
>                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-2631
>             Project: Hibernate3
>          Issue Type: Bug
>          Components: core
>    Affects Versions: 3.2.4
>         Environment: hibernate 3.2.3 with patch from HHH-2553
>            Reporter: Douglas A. Herrick
>            Assignee: Steve Ebersole
>             Fix For: 3.2.5, 3.3
>
>         Attachments: HHH-2631.patch
>
>
> While diagnosing an apparent resource issue, while running our application for a couple of hours I noticed over time that the number of PreparedStatement and ResultSet instances continued to grow, eventually consuming a fair amount of memory.  After digging around a bit, I saw that the entries LoadContext.java inserts into the map named collectionLoadContexts are not removed from the map [method cleanup(ResultSet resultSet)  might have removed them, but I never witnessed its invocation, nor did I find any references to it).
> I pasted below a stack trace that shows the insertion of elements into collectionLoadContexts:
> Thread [http-9943-Processor2] (Suspended (breakpoint at line 53 in CollectionLoadContext))	
> 	CollectionLoadContext.<init>(LoadContexts, ResultSet) line: 53	
> 	LoadContexts.getCollectionLoadContext(ResultSet) line: 85	
> 	BasicCollectionLoader(Loader).handleEmptyCollections(Serializable[], Object, SessionImplementor) line: 1060	
> 	BasicCollectionLoader(Loader).doQuery(SessionImplementor, QueryParameters, boolean) line: 690	
> 	BasicCollectionLoader(Loader).doQueryAndInitializeNonLazyCollections(SessionImplementor, QueryParameters, boolean) line: 236	
> 	BasicCollectionLoader(Loader).loadCollection(SessionImplementor, Serializable, Type) line: 1994	
> 	BasicCollectionLoader(CollectionLoader).initialize(Serializable, SessionImplementor) line: 36	
> 	BasicCollectionPersister(AbstractCollectionPersister).initialize(Serializable, SessionImplementor) line: 565	
> 	DefaultInitializeCollectionEventListener.onInitializeCollection(InitializeCollectionEvent) line: 60	
> 	SessionImpl.initializeCollection(PersistentCollection, boolean) line: 1716	
> 	PersistentSet(AbstractPersistentCollection).forceInitialization() line: 454	
> 	StatefulPersistenceContext.initializeNonLazyCollections() line: 785	
> 	QueryLoader(Loader).doQueryAndInitializeNonLazyCollections(SessionImplementor, QueryParameters, boolean) line: 241	
> 	QueryLoader(Loader).doList(SessionImplementor, QueryParameters) line: 2220	
> 	QueryLoader(Loader).listIgnoreQueryCache(SessionImplementor, QueryParameters) line: 2104	
> 	QueryLoader(Loader).list(SessionImplementor, QueryParameters, Set, Type[]) line: 2099	
> 	QueryLoader.list(SessionImplementor, QueryParameters) line: 378	
> 	QueryTranslatorImpl.list(SessionImplementor, QueryParameters) line: 338	
> 	HQLQueryPlan.performList(QueryParameters, SessionImplementor) line: 172	
> 	SessionImpl.list(String, QueryParameters) line: 1121	
> 	QueryImpl.list() line: 79	
> 	HibQuery.list() line: 60	
> 	HibRepository(AbstractRepository).query(IQuery, Class) line: 300	
>    ...
> While subsequent to this logic, hibernate does close the PreparedStatement and ResultSet instances, since it never removes them from collectionLoadContexts map, those instances are never GCed.  After running our application for a couple of days the amount of storage attributed to this potential leak is significant.

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