[hibernate-issues] [Hibernate-JIRA] Commented: (HHH-3006) ConcurrentModificationException in AbstractBatcher results in infinite loop

[John Mazzitelli (JIRA)]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-3006?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_29805 ] 

John Mazzitelli commented on HHH-3006:
--------------------------------------

I can say it is not related to Seam's usage of hibernate.  Just hit this with my JPA app (no Seam involved) going against Oracle 10g with hibernate v3.2.6+ (its actually a build from revision 14201) - and yes, app was under severe load:

Here's the log with stack in case its important:

2008-03-14 15:16:38,750 WARN  [org.hibernate.jdbc.AbstractBatcher] Could not close a JDBC result set
java.util.ConcurrentModificationException
	at java.util.HashMap$HashIterator.nextEntry(HashMap.java:841)
	at java.util.HashMap$KeyIterator.next(HashMap.java:877)
	at org.hibernate.jdbc.AbstractBatcher.closeStatements(AbstractBatcher.java:314)
	at org.hibernate.jdbc.ConnectionManager.cleanup(ConnectionManager.java:382)
	at org.hibernate.jdbc.ConnectionManager.close(ConnectionManager.java:324)
	at org.hibernate.impl.SessionImpl.close(SessionImpl.java:298)
	at org.hibernate.ejb.EntityManagerImpl.close(EntityManagerImpl.java:86)
	at org.jboss.ejb3.entity.ManagedEntityManagerFactory$SessionSynchronization.afterCompletion(ManagedEntityManagerFactory.java:129)
	at com.arjuna.ats.internal.jta.resources.arjunacore.SynchronizationImple.afterCompletion(SynchronizationImple.java:136)
	at com.arjuna.ats.arjuna.coordinator.TwoPhaseCoordinator.afterCompletion(TwoPhaseCoordinator.java:340)
	at com.arjuna.ats.arjuna.coordinator.TwoPhaseCoordinator.cancel(TwoPhaseCoordinator.java:107)
	at com.arjuna.ats.arjuna.AtomicAction.cancel(AtomicAction.java:230)
	at com.arjuna.ats.arjuna.coordinator.TransactionReaper.check(TransactionReaper.java:198)
	at com.arjuna.ats.internal.arjuna.coordinator.ReaperThread.run(ReaperThread.java:107)

> ConcurrentModificationException in AbstractBatcher results in infinite loop
> ---------------------------------------------------------------------------
>
>                 Key: HHH-3006
>                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-3006
>             Project: Hibernate3
>          Issue Type: Bug
>          Components: core
>    Affects Versions: 3.2.5
>         Environment: Hibernate 3.2.5.ga
> MySQL 5.0.42
>            Reporter: Stefan Hauk
>            Assignee: Steve Ebersole
>            Priority: Minor
>         Attachments: batcherinfinitelooptest.zip, batcherinfinitelooptest.zip
>
>
> Here is a piece of code from org.hibernate.jdbc.AbstractBatcher's closeStatements() method:
> Iterator iter = resultSetsToClose.iterator();
> while ( iter.hasNext() ) {
> 	try {
> 		logCloseResults();
> 		( (ResultSet) iter.next() ).close();
> 	}
> 	catch (SQLException e) {
> 		// no big deal
> 		log.warn("Could not close a JDBC result set", e);
> 	}
> 	catch (Throwable e) {
> 		// sybase driver (jConnect) throwing NPE here in certain cases
> 		log.warn("Could not close a JDBC result set", e);
> 	}
> }
> resultSetsToClose.clear();
> In case there is a ConcurrentModificationException thrown when iterating over the resultSetsToClose HashSet the exception will be caught by the catch(Throwable) clause. However, the iteration may continue infinitely because of the corrupted HashSet. This pegs one CPU and logs the following stack trace over and over again:
> 28/11 20:16:50 WARN AbstractBatcher [resin-tcp-connection-myserver:6001-15] Could not close a JDBC result set
> java.util.ConcurrentModificationException
> at java.util.HashMap$HashIterator.nextEntry(HashMap.java:841)
> at java.util.HashMap$KeyIterator.next(HashMap.java:877)
> at org.hibernate.jdbc.AbstractBatcher.closeStatements(AbstractBatcher.java:314)
> at org.hibernate.jdbc.ConnectionManager.cleanup(ConnectionManager.java:382)
> at org.hibernate.jdbc.ConnectionManager.close(ConnectionManager.java:324)
> at org.hibernate.impl.SessionImpl.close(SessionImpl.java:298)
> at org.springframework.orm.hibernate3.SessionFactoryUtils.closeSession(SessionFactoryUtils.java:774)
> at org.springframework.orm.hibernate3.support.OpenSessionInViewFilter.closeSession(OpenSessionInViewFilter.java:252)
> at org.springframework.orm.hibernate3.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:183)
> at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:75)
> at com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:70)
> at com.caucho.server.cache.CacheFilterChain.doFilter(CacheFilterChain.java:188)
> at com.caucho.server.webapp.WebAppFilterChain.doFilter(WebAppFilterChain.java:178)
> at com.caucho.server.dispatch.ServletInvocation.service(ServletInvocation.java:229)
> at com.caucho.server.hmux.HmuxRequest.handleRequest(HmuxRequest.java:419)
> at com.caucho.server.port.TcpConnection.run(TcpConnection.java:389)
> at com.caucho.util.ThreadPool.runTasks(ThreadPool.java:492)
> at com.caucho.util.ThreadPool.run(ThreadPool.java:425)
> at java.lang.Thread.run(Thread.java:595)
> The catch(Throwable) block was added in Hibernate 3.2.3 if I saw that correctly. Apparently the reason was to catch a NPE thrown by a sybase driver here, but catching Throwable catches more than that and produces this side-effect.
> Now I do realize that the ConcurrentModificationException might be caused by not using Hibernate in a correct way, but I haven't determined the cause for it yet. However, I do think that Hibernate should fail more gracefully than it currently does.

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