Hibernate 3.6.10.Final
Java 1.6 Update 39
App Server :- Weblogic 10.3.6

Under heavy load for our application, thread dumps taken and below blocking is coming for so many threads

"[ACTIVE] ExecuteThread: '54' for queue: 'weblogic.kernel.Default (self-tuning)'" daemon prio=3 tid=0x000000000593d800 nid=0x61 waiting for monitor entry [0
xfffffd7ff3146000]
java.lang.Thread.State: BLOCKED (on object monitor)
at java.lang.ClassLoader.loadClass(ClassLoader.java:291)
- waiting to lock <0xfffffd7f1037f4f8> (a weblogic.utils.classloaders.ChangeAwareClassLoader)
at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
at weblogic.utils.classloaders.GenericClassLoader.loadClass(GenericClassLoader.java:179)
at weblogic.utils.classloaders.ChangeAwareClassLoader.loadClass(ChangeAwareClassLoader.java:43)
at org.hibernate.util.ReflectHelper.classForName(ReflectHelper.java:187)
at org.hibernate.util.ReflectHelper.getConstantValue(ReflectHelper.java:266)
at org.hibernate.hql.ast.QueryTranslatorImpl$JavaConstantConverter.handleDotStructure(QueryTranslatorImpl.java:606)
at org.hibernate.hql.ast.QueryTranslatorImpl$JavaConstantConverter.visit(QueryTranslatorImpl.java:601)
at org.hibernate.hql.ast.util.NodeTraverser.visitDepthFirst(NodeTraverser.java:78)
at org.hibernate.hql.ast.util.NodeTraverser.traverseDepthFirst(NodeTraverser.java:66)
at org.hibernate.hql.ast.QueryTranslatorImpl.parse(QueryTranslatorImpl.java:282)
at org.hibernate.hql.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:184)
- locked <0xfffffd7fc89ee2f8> (a org.hibernate.hql.ast.QueryTranslatorImpl)
at org.hibernate.hql.ast.QueryTranslatorImpl.compile(QueryTranslatorImpl.java:138)
at org.hibernate.engine.query.HQLQueryPlan.<init>(HQLQueryPlan.java:101)
at org.hibernate.engine.query.HQLQueryPlan.<init>(HQLQueryPlan.java:80)
at org.hibernate.engine.query.QueryPlanCache.getHQLQueryPlan(QueryPlanCache.java:124)
at org.hibernate.impl.AbstractSessionImpl.getHQLQueryPlan(AbstractSessionImpl.java:156)
at org.hibernate.impl.SessionImpl.list(SessionImpl.java:1260)
at org.hibernate.impl.QueryImpl.list(QueryImpl.java:102)
at com.whg.xms.aricache.data.hibernate.ARIBaseDAO$2.doInHibernate(ARIBaseDAO.java:284)
at org.springframework.orm.hibernate3.HibernateTemplate.doExecute(HibernateTemplate.java:406)
at org.springframework.orm.hibernate3.HibernateTemplate.execute(HibernateTemplate.java:339)
at com.xxx.yyy.zzz.data.hibernate.XXXDAO.executeQuery(ARIBaseDAO.java:259)
at com.xxx.yyy.zzz.data.hibernate.ABCDAOImpl.findAllTTTId(ABCDAOImpl.java:559)
at sun.reflect.GeneratedMethodAccessor166.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:309)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:196)
at sun.proxy.$Proxy87.ZZZByRoomTypeAndRatePlanId(Unknown Source)
at com.xxx.yyy.zzz.service.YYYProcessorImpl.loadUUUIntoCacheLst(RestrictionsProcessorImpl.java:668)
at com.xxx.yyy.zzz.service.ABCImpl.loadUUUCacheLst(RestrictionsServiceImpl.java:588)
at com.xxx.yyy.zzz.handler.YlHandlerWork.run(RealTimeAvailHandlerWork.java:43)
at weblogic.work.j2ee.J2EEWorkManager$WorkWithListener.run(J2EEWorkManager.java:184)
at weblogic.work.ExecuteThread.execute(ExecuteThread.java:256)
at weblogic.work.ExecuteThread.run(ExecuteThread.java:221)

Please advise, how to resolve the ClassLoader.loadClass blocking?. Any suggestions welcome.

This issue was due to application using dynamic queries. Due to this, huge no of queryPlan cache getting generated. Defualt soft ref cache size is 2024. We are fixing the dynamic queries issue in application and instead use named variables so that queryPlan cache does not create large. This should provide huge amount of performance improvement for application and classloader.load class blocking should not happen.

We have lots of places in application where we are setting list of strings for "in" operator as part of HQL/native sql.



prt.rate_plan_id in (:ratePlanArray)

For ratePlanArray named variable, list of string is set setParameterList().

Hibernate is setting query string for Query Plan Cache key as:-

prt.rate_plan_id in (:ratePlanId0_, :ratePlanId1_, :ratePlanId2_, :ratePlanId3_, :ratePlanId4_, :ratePlanId5_)

This will generate huge no of distinct queries for query Plan cache. Is there way, Hibernate does put only names variable in the queryString for ParameterList.


prt.rate_plan_id in (:ratePlanArray)