**java.lang.OutOfMemoryError: Java heap space with Spring 4, Hibernate 4, My Sql connector 8.1 and tomcat 8.5** when using **My SQL 5.7.23*

Question

Here is the exception Details : -

java.lang.OutOfMemoryError: Java heap space
        at com.mysql.jdbc.Buffer.<init>(Buffer.java:57)
        at com.mysql.jdbc.MysqlIO.nextRow(MysqlIO.java:2087)
        at com.mysql.jdbc.MysqlIO.readSingleRowSet(MysqlIO.java:3549)
        at com.mysql.jdbc.MysqlIO.getResultSet(MysqlIO.java:489)
        at com.mysql.jdbc.MysqlIO.readResultsForQueryOrUpdate(MysqlIO.java:3240)
        at com.mysql.jdbc.MysqlIO.readAllResults(MysqlIO.java:2411)
        at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2834)
        at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2838)
        at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:2082)
        at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:2212)
        at sun.reflect.GeneratedMethodAccessor99.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at org.hibernate.engine.jdbc.internal.proxy.AbstractStatementProxyHandler.continueInvocation(AbstractStatementProxyHandler.java:122)
        at org.hibernate.engine.jdbc.internal.proxy.AbstractProxyHandler.invoke(AbstractProxyHandler.java:81)
        at com.sun.proxy.$Proxy168.executeQuery(Unknown Source)
        at org.hibernate.loader.Loader.getResultSet(Loader.java:1978)
        at org.hibernate.loader.Loader.doQuery(Loader.java:829)
        at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:289)
        at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:259)
        at org.hibernate.loader.Loader.loadCollectionSubselect(Loader.java:2242)
        at org.hibernate.loader.collection.SubselectOneToManyLoader.initialize(SubselectOneToManyLoader.java:77)
        at org.hibernate.persister.collection.AbstractCollectionPersister.initialize(AbstractCollectionPersister.java:622)
        at org.hibernate.event.internal.DefaultInitializeCollectionEventListener.onInitializeCollection(DefaultInitializeCollectionEventListener.java:82)
        at org.hibernate.internal.SessionImpl.initializeCollection(SessionImpl.java:1606)
        at org.hibernate.collection.internal.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:379)
        at org.hibernate.collection.internal.AbstractPersistentCollection.read(AbstractPersistentCollection.java:112)
        at org.hibernate.collection.internal.AbstractPersistentCollection.readSize(AbstractPersistentCollection.java:137)
        at org.hibernate.collection.internal.PersistentBag.isEmpty(PersistentBag.java:249)
        at com.vms.business.SupplierSearchService.fetchTopFiveAssociatedSuppliersList(SupplierSearchService.java:369)
        at com.vms.business.SupplierSearchService$$FastClassBySpringCGLIB$$c4e470d2.invoke(<generated>)
        at org.springframework.cglib.proxy.Meth

odProxy.invoke(MethodProxy.java:204)

Here is the Hibernate Query where I am getting exception :- **Note :- ** The same query works well when I use My SQL 5.1 with same data. One More thing when i use My SQL 5.7.23 RDS connection the whole application go slow. The new RDS has 4 time higher configuration from the 5.1 My SQL RDS service but still giving error.

Here is the query : -

Session session = em.unwrap(Session.class);
Criteria criteria = session.createCriteria(Orgassociation.class, "orgassociation");
criteria.createAlias("orgassociation.organization", "associatedOrgs");

Criteria userCriteria = session.createCriteria(User.class, "user");
userCriteria.add(Restrictions.eq("user.userId", userId));
User user = (User) userCriteria.uniqueResult();
criteria.add(Restrictions.eq("orgassociation.organization1.organizationId",
user.getOrganization().getOrganizationId()));
criteria.add(Restrictions.eq("associatedOrgs.orgType", VMS_CONSTANTS.DB_CONSTANTS.EMPLOYER_AND_SUPPLIER));
criteria.addOrder(Order.desc("orgassociation.orgAssociationId"));
criteria.setMaxResults(5);

@SuppressWarnings("unchecked")
List<Orgassociation> orgList = criteria.list();

Answer 1

You would need to attach a Java profiler (VisualVM) or Your kit and anaylse your heap to know which objects are actually causing this. It is very likely that some client sdk contract is broken resulting in a lot of java objects lying around without GC.