Problem w/lightweight impl

Guest · **Posted:** Wed Mar 03, 2004 10:43 am

I have a class SalesPacketVO, whose retrieval is taking an unacceptable amount of time due to its numerous children. BTW, this is in a Struts/EJB app using Hibernate 2.0.3 against MSSQL Server 8.00.760.

After reading article #41 I have decided to move the resource-consuming children into a heavyweight class that extends SalesPacketVO, HeavyweightSalesPacketVO. In order to avoid rewriting the original client code, I have set the heavyweight object as an unmapped instance variable on the lightweight one. When an accessor of a large child is called, I check if the heavyweight object exists, if not then load it and set it, and delegate future method calls to it rather than the containing lightweight (which is now kind of a delegation layer). I am experiencing problems in the load of the heavyweight.

Thank you in advance for your kind help.

Atif Faridi

===============================

Lightweight mapping:

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">

<hibernate-mapping>
<class name="com.terpsys.classic.data.vo.SalesPacketVO" table="SalesPacket">

<id name="id" unsaved-value="null" column="id">
<generator class="identity"/>
</id>

<property name="adverseFactorsComment"/>
<property name="alimony"/>
<property name="alternateDownPaymentComment"/>
<property name="bankruptcyComment"/>
<property name="childCare"/>
<property name="childSupport"/>
<property name="currentJudgmentsComment"/>
<property name="currentJudgmentsValue"/>
<property name="newContractAmount"/>
<property name="originalContractAmount"/>
<property name="salesPacketType" type="com.terpsys.classic.enum.SalesPacketType"/>
<property name="submissionStatus" type="com.terpsys.classic.enum.SalesPacketStatus"/>
<property name="alternateDownPayment" type="com.terpsys.classic.enum.TrueFalse"/>
<property name="adverseFactors" type="com.terpsys.classic.enum.TrueFalse"/>
<property name="readyToSubmit" type="com.terpsys.classic.enum.TrueFalse"/>
<property name="bankruptcy" type="com.terpsys.classic.enum.TrueFalse"/>
<property name="currentJudgments" type="com.terpsys.classic.enum.TrueFalse"/>
<property name="scheduleACreateDate"/>
<property name="financialInformationCreateDate"/>
<property name="projectId" insert="false" update="false"/>

<many-to-one
name="purchaser1"
class="com.terpsys.classic.data.vo.GuestVO"
column="purchaser1"
cascade="save-update"
not-null="false"/>

<many-to-one
name="purchaser2"
class="com.terpsys.classic.data.vo.GuestVO"
column="purchaser2"
cascade="save-update"
not-null="false"/>

<many-to-one
name="contract"
class="com.terpsys.classic.data.vo.ContractVO"
column="contractId"
cascade="save-update"
not-null="false"/>

<many-to-one
name="financingAddendum"
class="com.terpsys.classic.data.vo.FinancingAddendumVO"
column="financingAddendumId"
cascade="all"
not-null="false"/>

<many-to-one
name="brokerWaiver"
class="com.terpsys.classic.data.vo.BrokerWaiverVO"
column="brokerWaiverId"
cascade="all"
not-null="false"/>

<many-to-one
name="outsideLender"
class="com.terpsys.classic.data.vo.OutsideLenderVO"
column="outsideLenderId"
cascade="all"
not-null="false"/>

<many-to-one
name="outsideTitleCompany"
class="com.terpsys.classic.data.vo.OutsideTitleCompanyVO"
column="outsideTitleCompanyId"
cascade="all"
not-null="false"/>

<many-to-one
name="salesPacketSelectionSheetStatus"
class="com.terpsys.classic.data.vo.SalesPacketSelectionSheetStatusVO"
column="selectionSheetStatusId"
cascade="all"
not-null="false"/>

</class>

</hibernate-mapping>


===============================

Heavyweight mapping:

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">

<hibernate-mapping>

<class name="com.terpsys.classic.data.vo.HeavyweightSalesPacketVO" table="SalesPacket" polymorphism="explicit">

<id name="id" unsaved-value="null" column="id">
<generator class="identity"/>
</id>

<property name="adverseFactorsComment"/>
<property name="alimony"/>
<property name="alternateDownPaymentComment"/>
<property name="bankruptcyComment"/>
<property name="childCare"/>
<property name="childSupport"/>
<property name="currentJudgmentsComment"/>
<property name="currentJudgmentsValue"/>
<property name="newContractAmount"/>
<property name="originalContractAmount"/>
<property name="salesPacketType" type="com.terpsys.classic.enum.SalesPacketType"/>
<property name="submissionStatus" type="com.terpsys.classic.enum.SalesPacketStatus"/>
<property name="alternateDownPayment" type="com.terpsys.classic.enum.TrueFalse"/>
<property name="adverseFactors" type="com.terpsys.classic.enum.TrueFalse"/>
<property name="readyToSubmit" type="com.terpsys.classic.enum.TrueFalse"/>
<property name="bankruptcy" type="com.terpsys.classic.enum.TrueFalse"/>
<property name="currentJudgments" type="com.terpsys.classic.enum.TrueFalse"/>
<property name="scheduleACreateDate"/>
<property name="financialInformationCreateDate"/>
<property name="projectId" insert="false" update="false"/>

<many-to-one
name="trafficCard"
class="com.terpsys.classic.data.vo.TrafficCardVO"
column="trafficCardId"
cascade="none"
not-null="false"/>

<many-to-one
name="project"
class="com.terpsys.classic.data.vo.ProjectVO"
column="projectId"
cascade="none"
not-null="false"/>

<many-to-one
name="purchaser1"
class="com.terpsys.classic.data.vo.GuestVO"
column="purchaser1"
cascade="save-update"
not-null="false"/>

<many-to-one
name="purchaser2"
class="com.terpsys.classic.data.vo.GuestVO"
column="purchaser2"
cascade="save-update"
not-null="false"/>

<many-to-one
name="contract"
class="com.terpsys.classic.data.vo.ContractVO"
column="contractId"
cascade="save-update"
not-null="false"/>

<many-to-one
name="financingAddendum"
class="com.terpsys.classic.data.vo.FinancingAddendumVO"
column="financingAddendumId"
cascade="all"
not-null="false"/>

<many-to-one
name="brokerWaiver"
class="com.terpsys.classic.data.vo.BrokerWaiverVO"
column="brokerWaiverId"
cascade="all"
not-null="false"/>

<many-to-one
name="outsideLender"
class="com.terpsys.classic.data.vo.OutsideLenderVO"
column="outsideLenderId"
cascade="all"
not-null="false"/>

<many-to-one
name="outsideTitleCompany"
class="com.terpsys.classic.data.vo.OutsideTitleCompanyVO"
column="outsideTitleCompanyId"
cascade="all"
not-null="false"/>

<many-to-one
name="salesPacketSelectionSheetStatus"
class="com.terpsys.classic.data.vo.SalesPacketSelectionSheetStatusVO"
column="selectionSheetStatusId"
cascade="all"
not-null="false"/>

<many-to-one
name="defaultSpecialOptionRequest"
class="com.terpsys.classic.data.vo.SpecialOptionRequestVO"
column="defaultSpecialOptionRequestId"
cascade="all"
not-null="false"/>

<set name="assets" table="Asset" cascade="all-delete-orphan" inverse="true" lazy="false" order-by="assetType,description">
<key column="salesPacketId"/>
<one-to-many class="com.terpsys.classic.data.vo.AssetVO"/>
</set>

<set name="discountPromotions" table="DiscountPromotion" cascade="all-delete-orphan" inverse="true" lazy="false" order-by="description">
<key column="salesPacketId"/>
<one-to-many class="com.terpsys.classic.data.vo.DiscountPromoVO"/>
</set>

<set name="liabilities" table="Liability" cascade="all-delete-orphan" inverse="true" lazy="false" order-by="liabilityType,description">
<key column="salesPacketId"/>
<one-to-many class="com.terpsys.classic.data.vo.LiabilityVO"/>
</set>

<set name="selectedOptions" table="SelectedOption" cascade="all-delete-orphan" inverse="true" lazy="false" order-by="scheduleAOptionId">
<key column="salesPacketId"/>
<one-to-many class="com.terpsys.classic.data.vo.SelectedOptionVO"/>
</set>

</class>

</hibernate-mapping>


===============================

Hibernate code:

...
try
{
Long pId = lLite.getId();
lSession = HibernateConfigurationSingleton.openSession();
lTx = lSession.beginTransaction();
lSession.evict(lLite);

//2 other things I've tried and gotten the same results:

//(1)
//lSession.evict(lSession.find("FROM com.terpsys.classic.data.vo.SalesPacketVO o WHERE o.id = ?", pId, Hibernate.LONG).get(0));

//(2)
//SessionFactory lSessionFactory = HibernateConfigurationSingleton.getSessionFactory();
//lSessionFactory.evict(SalesPacketVO.class, pId);

//This is where it bombs
lResults =
(HeavyweightSalesPacketVO) lSession.load(
HeavyweightSalesPacketVO.class,
pId);
...

===============================

Relevant part of the stack trace:
...

09:21:18,079 ERROR [SalesPacketDAO] Object with id: 778 was not of the specified subclass: com.terpsys.classic.data.vo.HeavyweightSalesPacketVO (loaded object was of wrong class)
net.sf.hibernate.WrongClassException: Object with id: 778 was not of the specified subclass: com.terpsys.classic.data.vo.HeavyweightSalesPacketVO (loaded object was of wrong class)
at net.sf.hibernate.loader.Loader.instanceAlreadyLoaded(Loader.java:300)
at net.sf.hibernate.loader.Loader.getRow(Loader.java:278)
at net.sf.hibernate.loader.Loader.doFind(Loader.java:159)
at net.sf.hibernate.loader.Loader.loadEntity(Loader.java:587)
at net.sf.hibernate.loader.EntityLoader.load(EntityLoader.java:42)
at net.sf.hibernate.persister.EntityPersister.load(EntityPersister.java:396)
at net.sf.hibernate.impl.SessionImpl.doLoad(SessionImpl.java:1889)
at net.sf.hibernate.impl.SessionImpl.doLoadByClass(SessionImpl.java:1757)
at net.sf.hibernate.impl.SessionImpl.load(SessionImpl.java:1688)
at com.terpsys.classic.data.dao.SalesPacketDAO.fetchHeavyweight(SalesPacketDAO.java:264)
at com.terpsys.classic.session.salespacket.SalesPacketBean.fetchHeavyweight(SalesPacketBean.java:161)
...

===============================

emmanuel · **Posted:** Wed Mar 03, 2004 1:42 pm

Is HeavyweightSalesPacketVO a subclass of SalesPacketVO

Guest · **Posted:** Wed Mar 03, 2004 2:21 pm

Yes. Sorry about forgetting to mention that. Wanna see the code?

emmanuel · **Posted:** Wed Mar 03, 2004 6:00 pm

Hum is your code as simple as that ?
try to remove any extra property and association, then add it one by one

Guest · **Posted:** Thu Mar 04, 2004 2:13 am

I figured it out, and your comments were definitely on the right track. It turns out that some of the grand-child entities of HeavyweightSalesPacketVO were of type SalesPacketVO - its superclass. Due to this incestuous relationship in which an object's parent is also its grandchild, the following code (in Loader.java) would throw an exception since

HeavyweightSalesPacketVO.class.isAssignableFrom(SalesPacketVO.class)

is false.

...
private void instanceAlreadyLoaded(ResultSet rs, int i, Loadable persister, String suffix, Key key, Object object, LockMode lockMode, SessionImplementor session)
throws HibernateException, SQLException {

if ( !persister.getMappedClass().isAssignableFrom( object.getClass() ) )
throw new WrongClassException( "loaded object was of wrong class", key.getIdentifier(), persister.getMappedClass() );
...

Incest is bad, so HeavyweightSalesPacketVO's children's mappings to SalesPacketVO were changed to HeavyweightSalesPacketVO. It turns out that the children are only obtained through a SalesPacketVO instance so we don't have to worry about needlessly loading the heavyweight object. I don't know why the references are there in the first place.

Thank you very much for the prompt response.

Atif Faridi