I am trying to troubleshoot a problem with hibernate running a J2EE Seam application on a jboss AS7.1 using hibernate-core 3.6.5.Final. One thread on Jboss was dominating the computers CPU. The threads stack trace is below. This stack trace remained unchanged for 20+ minutes. It looks like hibernate is stuck looking up a value in StatefulPersistenceContext's identitymap. A heap dump revealed that the contained a large number of entries (24689). Any ideas on why the thread would consume so much cpu to find an entry in the map?

---------------Stack trace ----------------------
"http--0.0.0.0-2080-202" - Thread t@6053
java.lang.Thread.State: RUNNABLE
at java.util.HashMap.getEntry(HashMap.java:364)
at java.util.HashMap.containsKey(HashMap.java:352)
at org.hibernate.engine.StatefulPersistenceContext.containsEntity(StatefulPersistenceContext.java:372)
at org.hibernate.type.ManyToOneType.scheduleBatchLoadIfNeeded(ManyToOneType.java:161)
at org.hibernate.type.ManyToOneType.hydrate(ManyToOneType.java:148)
at org.hibernate.persister.entity.AbstractEntityPersister.hydrate(AbstractEntityPersister.java:2283)
at org.hibernate.loader.Loader.loadFromResultSet(Loader.java:1527)
at org.hibernate.loader.Loader.instanceNotYetLoaded(Loader.java:1455)
at org.hibernate.loader.Loader.getRow(Loader.java:1355)
at org.hibernate.loader.Loader.getRowFromResultSet(Loader.java:611)
at org.hibernate.loader.Loader.doQuery(Loader.java:829)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:274)
at org.hibernate.loader.Loader.loadEntity(Loader.java:2037)
at org.hibernate.loader.entity.AbstractEntityLoader.load(AbstractEntityLoader.java:86)
at org.hibernate.loader.entity.AbstractEntityLoader.load(AbstractEntityLoader.java:76)
at org.hibernate.persister.entity.AbstractEntityPersister.load(AbstractEntityPersister.java:3293)
at org.hibernate.event.def.DefaultLoadEventListener.loadFromDatasource(DefaultLoadEventListener.java:496)
at org.hibernate.event.def.DefaultLoadEventListener.doLoad(DefaultLoadEventListener.java:477)
at org.hibernate.event.def.DefaultLoadEventListener.load(DefaultLoadEventListener.java:227)
at org.hibernate.event.def.DefaultLoadEventListener.onLoad(DefaultLoadEventListener.java:147)
at org.hibernate.impl.SessionImpl.fireLoad(SessionImpl.java:1090)
at org.hibernate.impl.SessionImpl.immediateLoad(SessionImpl.java:1026)
at org.hibernate.proxy.AbstractLazyInitializer.initialize(AbstractLazyInitializer.java:176)
at org.hibernate.proxy.AbstractLazyInitializer.getImplementation(AbstractLazyInitializer.java:215)
at org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer.invoke(JavassistLazyInitializer.java:190)
at com.eclipseinc.client.jobmg.bidding.quote.persistence.CustomerQuote_$$_javassist_48.getName(CustomerQuote_$$_javassist_48.java)
at sun.reflect.GeneratedMethodAccessor554.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:616)
at javax.el.BeanELResolver.getValue(BeanELResolver.java:302)
at com.sun.faces.el.DemuxCompositeELResolver._getValue(DemuxCompositeELResolver.java:173)
at com.sun.faces.el.DemuxCompositeELResolver.getValue(DemuxCompositeELResolver.java:200)
at org.jboss.el.parser.AstPropertySuffix.getValue(AstPropertySuffix.java:53)
at org.jboss.el.parser.AstValue.getValue(AstValue.java:67)
at org.jboss.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:186)
at com.sun.facelets.el.TagValueExpression.getValue(TagValueExpression.java:71)
at org.richfaces.model.impl.expressive.ValueBindingExpression.evaluate(ValueBindingExpression.java:79)
at org.richfaces.model.impl.expressive.ObjectWrapperFactory.wrapObject(ObjectWrapperFactory.java:209)
at org.richfaces.model.ModifiableModel$RowKeyWrapperFactory.wrapObject(ModifiableModel.java:75)
at org.richfaces.model.impl.expressive.ObjectWrapperFactory$2.convert(ObjectWrapperFactory.java:190)
at org.richfaces.model.impl.expressive.ObjectWrapperFactory.convertList(ObjectWrapperFactory.java:151)
at org.richfaces.model.impl.expressive.ObjectWrapperFactory.wrapList(ObjectWrapperFactory.java:188)
at org.richfaces.model.ModifiableModel.filter(ModifiableModel.java:252)
at org.richfaces.model.ModifiableModel.modify(ModifiableModel.java:240)
at org.richfaces.component.UIExtendedDataTable.createDataModel(UIExtendedDataTable.java:376)
at org.ajax4jsf.component.UIDataAdaptorBase.getExtendedDataModel(UIDataAdaptorBase.java:621)
at org.ajax4jsf.component.UIDataAdaptorBase.getRowCount(UIDataAdaptorBase.java:248)
at org.richfaces.component.UIDatascroller.getRowCount(UIDatascroller.java:362)
at org.richfaces.component.UIDatascroller.getPageCount(UIDatascroller.java:334)
at org.richfaces.component.UIDatascroller.getPageCount(UIDatascroller.java:358)
at org.richfaces.renderkit.html.DatascrollerTemplate.doEncodeEnd(DatascrollerTemplate.java:185)
at org.richfaces.renderkit.html.DatascrollerTemplate.doEncodeEnd(DatascrollerTemplate.java:682)
at org.ajax4jsf.renderkit.RendererBase.encodeEnd(RendererBase.java:134)
at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:864)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:937)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:933)
at javax.faces.render.Renderer.encodeChildren(Renderer.java:148)
at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:840)
at org.ajax4jsf.renderkit.RendererBase.renderChild(RendererBase.java:277)
at org.ajax4jsf.renderkit.AjaxChildrenRenderer.encodeAjaxComponent(AjaxChildrenRenderer.java:166)
at org.ajax4jsf.renderkit.AjaxChildrenRenderer.encodeAjaxChildren(AjaxChildrenRenderer.java:83)
at org.ajax4jsf.renderkit.AjaxChildrenRenderer.encodeAjaxComponent(AjaxChildrenRenderer.java:157)
at org.ajax4jsf.renderkit.AjaxChildrenRenderer.encodeAjaxChildren(AjaxChildrenRenderer.java:83)
at org.ajax4jsf.renderkit.AjaxChildrenRenderer.encodeAjaxComponent(AjaxChildrenRenderer.java:157)
at org.ajax4jsf.renderkit.AjaxContainerRenderer.encodeAjax(AjaxContainerRenderer.java:124)
at org.ajax4jsf.component.AjaxViewRoot.encodeAjax(AjaxViewRoot.java:685)
at org.ajax4jsf.component.AjaxViewRoot.encodeChildren(AjaxViewRoot.java:556)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:930)
at com.sun.facelets.FaceletViewHandler.renderView(FaceletViewHandler.java:592)
at org.ajax4jsf.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:100)
at org.ajax4jsf.application.AjaxViewHandler.renderView(AjaxViewHandler.java:176)
at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:110)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:100)
at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:139)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:266)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:329)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:248)
at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:83)
at org.jboss.seam.web.RewriteFilter.doFilter(RewriteFilter.java:63)
at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
at org.jboss.seam.web.ExceptionFilter.doFilter(ExceptionFilter.java:64)
at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
at com.eclipseinc.client.jobmg.security.business.JMSessionFilter.doFilter(JMSessionFilter.java:85)
at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
at org.jboss.seam.web.RedirectFilter.doFilter(RedirectFilter.java:45)
at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
at org.ajax4jsf.webapp.BaseXMLFilter.doXmlFilter(BaseXMLFilter.java:206)
at org.ajax4jsf.webapp.BaseFilter.handleRequest(BaseFilter.java:295)
at org.ajax4jsf.webapp.BaseFilter.processUploadsAndHandleRequest(BaseFilter.java:393)
at org.ajax4jsf.webapp.BaseFilter.doFilter(BaseFilter.java:520)
at org.jboss.seam.web.Ajax4jsfFilter.doFilter(Ajax4jsfFilter.java:56)
at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
at org.jboss.seam.web.LoggingFilter.doFilter(LoggingFilter.java:60)
at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
at org.jboss.seam.web.HotDeployFilter.doFilter(HotDeployFilter.java:53)
at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
at org.jboss.seam.web.IdentityFilter.doFilter(IdentityFilter.java:40)
at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
at org.jboss.seam.servlet.SeamFilter.doFilter(SeamFilter.java:158)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:280)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:248)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:275)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:161)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:397)
at org.jboss.as.jpa.interceptor.WebNonTxEmCloserValve.invoke(WebNonTxEmCloserValve.java:50)
at org.jboss.as.web.security.SecurityContextAssociationValve.invoke(SecurityContextAssociationValve.java:154)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:155)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.jboss.web.rewrite.RewriteValve.invoke(RewriteValve.java:466)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:368)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:877)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:671)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:930)
at java.lang.Thread.run(Thread.java:679)

Locked ownable synchronizers:
- None

-------------- application code --------------------
@Entity
@Table(name="job_customer")
public class CustomerQuote extends Quote implements Serializable{

}

@MappedSuperclass
public class Quote implements Serializable
{
@Column(name="name")
public String getName()
{
return name;
}

@Override
public int hashCode()
{
int result = 17;
return 17*result + this.getJobId() + this.getActorId();
}
}

When the amount of entities are very high in the session and in particular when associations are numerous, the flush operation will need to go through it's persistence context a lot. So while seeing it dominate your application is a little surprising, it's not necessary inconceivable.
We did improve that part significantly in the 4.x series and in particular the latests version. I highly encourage you to migrate if you can. And before you ask, these improvements have been a hard uphill battle one small improvement at a time. Backporting would not be an easy task.