[hibernate-issues] [Hibernate-JIRA] Commented: (HHH-1523) LazyInitializationError on enabling query cache...
Martijn van Tilburg (JIRA)
noreply at atlassian.com
Mon Jul 7 06:05:40 EDT 2008
[ http://opensource.atlassian.com/projects/hibernate/browse/HHH-1523?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_30581 ]
Martijn van Tilburg commented on HHH-1523:
------------------------------------------
We run into this issue as well in an EJB3 project. We use:
JBoss AS 4.2.0 as application server
Hibernate 3.2.3.ga as JPA entity manager
JBossCache 1.4.1.SP3 as second level cache
We use annotations to define our mappings, example:
[code]
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.ManyToMany;
import javax.persistence.Table;
import javax.persistence.UniqueConstraint;
import org.hibernate.annotations.Cache;
import org.hibernate.annotations.CacheConcurrencyStrategy;
...
@Entity
@Cache(usage=CacheConcurrencyStrategy.TRANSACTIONAL)
@Table(name = "user",uniqueConstraints={@UniqueConstraint(columnNames={"name"})})
public class User extends BaseValueObject {
...
@ManyToMany (fetch=FetchType.LAZY)
@Cache(usage=CacheConcurrencyStrategy.TRANSACTIONAL)
public Set<Right> getRights() {
return rights;
}
...
}
[/code]
NOTE: The 'Right' entity also has the @Cache annotation applied.
Sometimes we want to fetch the 'Right' collection of 'User' but sometimes not, example EJBQL with fetching:
[code]
import javax.ejb.Local;
import javax.ejb.Stateless;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
...
@Stateless
@Local( { IConfigHelperBean.class })
public class ConfigHelperBean implements IConfigHelperBean {
@PersistenceContext(unitName = "sampleApp")
private EntityManager em;
public User getUserByNameWithFetchJoin(String userName) {
return em.createQuery("SELECT u FROM User u LEFT JOIN FETCH u.rights WHERE user.name = :userName").setParameter("userName", userName).setHint("org.hibernate.cacheable", new Boolean(true)).getSingleResult();
}
}
[/code]
The caching of the entities and the query seems to work correctly until we try to touch the user.rights collection after the EJB transaction has ended (and thus the EntityManager session is closed). We then are presented with the familiar LazyInitializationException as thrown by the PersistentSet implementation. This only happens when the query is executed for the second time and its results are in the second level cache (which we verified by inspecting the cache with the JBossCache MBean that is deployed in our JBoss AS). If we touch the 'rights' collection (by invoking its 'size' method) before the EJB transaction ends the LazyInitializationException is not thrown anymore. The MySql server log indicates no SQL queries are invoked anymore, this proves the second level cache works as it should.
Recently the following was posted on the hibernate.org main page
"28.04.2008 - Hibernate Core 3.3.0.CR1
This new release features:
* a redesign of the "second level cache" SPI
* a new integration with JBossCache 2.x taking full advantage of this new SPI (special thanks to Brian Stansberry for his help and hard work on this)
* introduction of the org.hibernate.jdbc.Work API for performing JDBC work without interfering with connection release modes
Additionally, this is the first release done from the new Maven project structure. The Maven artifacts are deployed to the JBoss Maven repository under the groupId org.hibernate. We also do still build a distribution bundle and upload it to SourceForge here."
Is there any hope Hibernate 3.3.0 will solve this longstanding major bug?
> LazyInitializationError on enabling query cache...
> --------------------------------------------------
>
> Key: HHH-1523
> URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-1523
> Project: Hibernate3
> Issue Type: Bug
> Components: core
> Affects Versions: 3.0.5, 3.1
> Environment: 3.0.1 and 3.1, HSQLDB and Oracle
> Reporter: Vikas Sasidharan
> Attachments: cache_issue.log, QueryCacheIssue.zip
>
>
> I have two domain objects - Employee and Department - and there is a 1:N relationship from Department to Employee. When I join fetch an Employee with its Department, without query cache enabled, it works fine. If I enable query cache for this same query, it bombs with a LazyInitializationException.
> Notes:
> 1) We get this error only if query cache is enabled.
> 2) We observed the same behaviour on both oscache and ehcache
> 3) Calling Hibernate.initialize() explicitly after firing the HQL seems to work. The initialization does not fire an extra query though (it seems to pick it from the cache).
> 4) Setting "lazy=false" on the "many-to-one" mapping also works. However, it wouldn't be acceptable.
> Hibernate version: 3.0.5
> Mapping documents:
> Employee.hbm.xml
> <hibernate-mapping>
> <class name="tavant.platform.test.domain.Employee"
> table="CACHE_ISSUE_EMP" lazy="true" dynamic-update="true" dynamic-insert="true">
> <cache usage="read-write" />
> <id name="id" column="EMP_ID" type="java.lang.Long"
> access="field" unsaved-value="null">
> <generator class="increment" />
> </id>
>
> <property name="name" type="string" update="true"
> insert="true" column="EMP_NAME"/>
> <many-to-one name="department" class="tavant.platform.test.domain.Department"
> cascade="none" outer-join="auto" update="true" insert="true" column="DEPARTMENT_ID"/>
> </class>
> </hibernate-mapping>
>
> Department.hbm.xml
> <hibernate-mapping>
> <class name="tavant.platform.test.domain.Department" table="CACHE_ISSUE_DEP"
> lazy="true" dynamic-update="true" dynamic-insert="true">
>
> <cache usage="read-write" />
> <id name="id" column="DEPARTMENT_ID"
> type="java.lang.Long" access="field">
> <generator class="increment"/>
> </id>
> <property name="name" type="java.lang.String"
> update="false" insert="true" column="NAME"/>
> <bag name="employees" lazy="true"
> inverse="true" cascade="save-update" access="field">
> <cache usage="read-write"/>
> <key column="DEPARTMENT_ID"/>
> <one-to-many class="tavant.platform.test.domain.Employee"/>
> </bag>
> </class>
> </hibernate-mapping>
>
> Code between sessionFactory.openSession() and session.close():
> public Employee getEmployeeWithDepartment(String empName) {
> Session session = null;
> try {
> session = sessionFactory.openSession();
> Employee emp = (Employee) session.createQuery(
> "from Employee e join fetch e.department where e.name = :name")
> .setString("name", empName)
> .setCacheable(true)
> .uniqueResult();
> // If I uncomment the next line, this works (even without
> // firing an extra query)!
> // Hibernate.initialize(emp.getDepartment());
> return emp;
> } finally {
> if (session != null) {
> session.close();
> }
> }
> }
>
> // First load employee and populate cahces
> Employee emp = test.getEmployeeWithDepartment(EMPLOYEE_NAME);
> System.out.println("Employee : " + emp + ", Employee.Department : "
> + emp.getDepartment());
>
> // Now try to make use of the cache
> emp = test.getEmployeeWithDepartment(EMPLOYEE_NAME);
> System.out.println("Employee : " + emp + ", Employee.Department : "
> + emp.getDepartment());
>
> Full stack trace of any exception that occurs:
> org.hibernate.LazyInitializationException: could not initialize proxy - the owning Session was closed
> at org.hibernate.proxy.AbstractLazyInitializer.initialize(AbstractLazyInitializer.java:53)
> at org.hibernate.proxy.AbstractLazyInitializer.getImplementation(AbstractLazyInitializer.java:84)
> at org.hibernate.proxy.CGLIBLazyInitializer.intercept(CGLIBLazyInitializer.java:134)
> at tavant.platform.test.domain.Department$$EnhancerByCGLIB$$67b26899.toString(<generated>)
> at java.lang.String.valueOf(String.java:2131)
> at java.lang.StringBuffer.append(StringBuffer.java:370)
> at tavant.platform.test.client.TestPrefetchRelationWithQueryCacheEnabled.main(TestPrefetchRelationWithQueryCacheEnabled.java:116)
>
> Name and version of the database you are using:
> We have noticed this on Oracle and HSQL
> The generated SQL (show_sql=true):
> #First read, goes fine
> Hibernate: select employee0_.EMP_ID as EMP1_0_, department1_.DEPARTMENT_ID as DEPARTMENT1_1_, employee0_.EMP_NAME as EMP2_1_0_, employee0_.DEPARTMENT_ID as DEPARTMENT3_1_0_, department1_.NAME as NAME0_1_ from CACHE_ISSUE_EMP employee0_ inner join CACHE_ISSUE_DEP department1_ on employee0_.DEPARTMENT_ID=department1_.DEPARTMENT_ID where (employee0_.EMP_NAME=? )
> #Prints the Employee and Department fine
> Employee : [Id : 1, name : testEmployee], Employee.Department : [Id : 1, name : testDepartment]
> #Second read bombs!
> org.hibernate.LazyInitializationException: could not initialize proxy - the owning Session was closed
> at org.hibernate.proxy.AbstractLazyInitializer.initialize(AbstractLazyInitializer.java:53)
> at org.hibernate.proxy.AbstractLazyInitializer.getImplementation(AbstractLazyInitializer.java:84)
> at org.hibernate.proxy.CGLIBLazyInitializer.intercept(CGLIBLazyInitializer.java:134)
> [..]
> Please have a look at the post [http://forum.hibernate.org/viewtopic.php?t=955839] for more details and follow ups.
> Kindly help. I am attaching an Eclipse Project containing the TestCase. The main file is TestPrefetchRelationWithQueryCacheEnabled.
> Thanks,
> Vikas
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