[hibernate-issues] [Hibernate-JIRA] Commented: (HHH-1523) LazyInitializationError on enabling query cache...

[Faizal Abdoelrahman (JIRA)]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-1523?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_29051 ] 

Faizal Abdoelrahman commented on HHH-1523:
------------------------------------------

Hi Erik,

I saw that page and indeed resorted to traversing the rather complicated graph I have and putting hibernate.initialize everywhere. Way uncool!! Why don't they mark "left join fetch" deprecated then, as hibernate.initialize seems to be the official answer ?  
What annoys me is that turning query cache on actually breaks the application whereas running without gives no problems. There are more errors down the road since I have passed this stage. ObjectNotNound exceptions when you delete an object that was in a collection cache. The official hibernate answer is to properly maintain your object graph (which makes sense) and delete the object yourself from your graph. However some objects I don't have access to since they are contained in totally different use-cases.

Anyway luckily I can resort to workarounds (like hibernate.initialize and evicting the collection cache manually for the other problems).
Hope they close this bug shortly, it's been lingering around for too long.

Regards,

Faizal Abdoelrahman




> 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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