[hibernate-issues] [Hibernate-JIRA] Commented: (HHH-1523) Rebuild fetches from query-cache hits
Julien Kronegg (JIRA)
noreply at atlassian.com
Fri Nov 11 11:08:26 EST 2011
[ http://opensource.atlassian.com/projects/hibernate/browse/HHH-1523?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=44301#comment-44301 ]
Julien Kronegg commented on HHH-1523:
-------------------------------------
[SOLVED] I followed the code modification proposed by [Titi|https://hibernate.onjira.com/browse/HHH-1523?focusedCommentId=38668&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-38668] and made the following ones (for Hibernate 3.3.1) :
# create a {{mypackage.CustomCacheLoadEventListener}} class extending {{org.hibernate.event.def.DefaultLoadEventListener}}
# override the {{proxyOrLoad()}}, {{createProxyIfNecessary()}} and {{returnNarrowedProxy()}} methods with the same code as in the parent class
# modify the {{createProxyIfNecessary()}} method as proposed by Titi, i.e. changing from
{code}
log.trace( "creating new proxy for entity" );
// return new uninitialized proxy
Object proxy = persister.createProxy( event.getEntityId(), event.getSession() );
persistenceContext.getBatchFetchQueue().addBatchLoadableEntityKey(keyToLoad);
persistenceContext.addProxy(keyToLoad, proxy);
return proxy;
{code}
to
{code}
final Object cached = loadFromSecondLevelCache(event, persister, options);
if (cached != null) {
// found in L2 cache => return it
return cached;
} else {
// not found in L2 cache => return a proxy
log.trace("creating new proxy for entity");
// return new uninitialized proxy
final Object proxy = persister.createProxy(event.getEntityId(), event.getSession());
persistenceContext.getBatchFetchQueue().addBatchLoadableEntityKey(keyToLoad);
persistenceContext.addProxy(keyToLoad, proxy);
return proxy;
}
{code}
# in the {{persistence.xml}}, add the following property:
{code}
<property name="hibernate.ejb.event.load" value="mypackage.CustomCacheLoadEventListener"/>
{code}
That's all!
Now, if I execute the test case from my previous post, I get no {{LazyInitializationException}}, which is the expected result.
Thanks a lot Titi!
> Rebuild fetches from query-cache hits
> -------------------------------------
>
> Key: HHH-1523
> URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-1523
> Project: Hibernate Core
> Issue Type: New Feature
> Components: caching (L2), core, query-criteria, query-hql, query-sql
> Affects Versions: 3.0.5, 3.1
> 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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