[hibernate-issues] [Hibernate-JIRA] Commented: (HHH-2318) Sometimes wrong classloader used for proxy interfaces

Lars J. Nilsson (JIRA) noreply at atlassian.com
Sun May 27 17:29:04 EDT 2007


    [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-2318?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_27058 ] 

Lars J. Nilsson commented on HHH-2318:
--------------------------------------

Bumping this issue. I currently have a setup where one class loader (lets call it "B") exposes JPA interfaces as a service towards modules in a sibling class loader ("C"). These two class loaders share the parent class loader ("A") which load the JPA classes but not the hibernate classes. It appears this issue stops us from from using lazy loading. 

Is there any way to disable lazy loading in configuration when using JPA? Currently I've patched the hibernate to forcibly disable lazy loading, which is of course not very desirable.


> Sometimes wrong classloader used for proxy interfaces
> -----------------------------------------------------
>
>                 Key: HHH-2318
>                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-2318
>             Project: Hibernate3
>          Issue Type: Bug
>          Components: core
>    Affects Versions: 3.2.1
>            Reporter: Jan Wiemer
>         Attachments: ProxyIfcNamespaceProblem.zip
>
>
> For some of our business classes we used a Mapping declaring the class to be lazy initialized and providing a proxy interface like e.g.:
>  <class name="TestClassImpl" proxy="TestClass" table="testTable" lazy="true"> ... </class>
> Using classes mapped this way - e.g. as endpoint of  a one to one relation - sporadically leads to exceptions like the following:
> org.hibernate.PropertyAccessException: IllegalArgumentException occurred while calling setter of  test.AbstractTestClass2Impl.testField
> 	at org.hibernate.property.BasicPropertyAccessor$BasicSetter.set(BasicPropertyAccessor.java:104)
> 	at org.hibernate.tuple.entity.AbstractEntityTuplizer.setPropertyValues(AbstractEntityTuplizer.java:337)
> 	at org.hibernate.tuple.entity.PojoEntityTuplizer.setPropertyValues(PojoEntityTuplizer.java:200)
> 	at org.hibernate.persister.entity.AbstractEntityPersister.setPropertyValues(AbstractEntityPersister.java:3514)
> 	at org.hibernate.engine.TwoPhaseLoad.initializeEntity(TwoPhaseLoad.java:129)
> 	at org.hibernate.loader.Loader.initializeEntitiesAndCollections(Loader.java:842)
> 	at org.hibernate.loader.Loader.doQuery(Loader.java:717)
> 	at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:224)
> 	at org.hibernate.loader.Loader.doList(Loader.java:2211)
> 	at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2095)
> 	at org.hibernate.loader.Loader.list(Loader.java:2090)
> 	at org.hibernate.loader.hql.QueryLoader.list(QueryLoader.java:388)
> 	at org.hibernate.hql.ast.QueryTranslatorImpl.list(QueryTranslatorImpl.java:338)
> 	at org.hibernate.engine.query.HQLQueryPlan.performList(HQLQueryPlan.java:172)
> 	at org.hibernate.impl.SessionImpl.list(SessionImpl.java:1121)
> 	at org.hibernate.impl.QueryImpl.list(QueryImpl.java:79)
> 	at org.hibernate.impl.AbstractQueryImpl.uniqueResult(AbstractQueryImpl.java:804)
> Note that the application is residing in a different classloader than hibernate (and CGLIB...).
> Examining the situation we see that the value passed to the setter was a CGLIB proxy. Internally the proxy stores an array of interfaces the proxy should implement. In our situation this interface contains the HibernateProxy interface and our business interface provided as proxy interface in the mapping. In this interface array we checked the classloader of the interfaces. As expected the HibernateProxy interface is loaded by the system classloader and our interface was loaded by our custom classloader. However examining the actual interfaces of the proxy (with proxy.getClass().getInterfaces()[i].getClassLoader() for all i) shows that all interfaces are loaded with the system classloader. This causes the exception above.
> Doing some more experiments we experience that the problem does not occur all the time. Sometimes the actual proxy interfaces are as expected (the HibernateProxy interface is loaded by the system classloader and our interface was loaded by our custom classloader). We notice that each time the test failed the HibernateProxy was the first interface in the interface array stored in the proxy.
> Some experiments with the CGLIB (the Enhancer class) shows us that (if there is no superclass given) they use the classloader of the first passed interface as default classloader (compare method net.sf.cglib.proxy.Enhancer.getDefaultClassLoader()).
> Finally we find out that hibernate passes the proxy interfaces in an arbitrary order since they are using a HashSet for the proxy interfaces in the method org.hibernate.tuple.entity.PojoEntityTuplizer.buildProxyFactory(PersistentClass persistentClass, Getter idGetter, Setter idSetter). This Hash set is passed to the method org.hibernate.proxy.pojo.cglib.CGLIB_ProxyFactory.postInstantiate(...). There it is simply converted to an Array (leading to a randomized order).
>  As a workaround it is possible to patch the class org.hibernate.proxy.pojo.cglib.CGLIB_ProxyFactory and  add reorganize the array if the HibernateProxy interface is the first one:
>     this.interfaces = (Class[]) interfaces.toArray(NO_CLASSES);
>     //----->PATCH<-------- 
>     if(this.interfaces.length > 1) {
>       Class firstIfc = this.interfaces[0];
>       if(firstIfc.getName().startsWith("org.hibernate")) {
>         this.interfaces[0] = this.interfaces[1];
>         this.interfaces[1] = firstIfc;
>         System.err.println("Replace: " + firstIfc.getName() + " by " + this.interfaces[0].getName());
>       }
>     }
>     //-------------------- 
> After applying this patch everything woks as expected.
> Compare with the discussion in: 
> http://forum.hibernate.org/viewtopic.php?p=2334617#2334617

-- 
This message is automatically generated by JIRA.
-
If you think it was sent incorrectly contact one of the administrators: http://opensource.atlassian.com/projects/hibernate/secure/Administrators.jspa
-
For more information on JIRA, see: http://www.atlassian.com/software/jira

        



More information about the hibernate-issues mailing list