[Hibernate-issues] Re: [Hibernate] Hibernate Bug? [ConcurrentModificationException]

[Gavin K. <ga...@hi...>]

We seem to be having some problems like this in more than one section
of code. I really don't understand it at all; we suspect some kind of
JVM bug. Unfortunately, no-one has been able to deliver a testcase
that will help me reproduce this on my machine.

I can't really do much, until I can reproduce it.

P.S. You might also get this if you share a session between two
threads - but at least some occurrences of this problem do not seem
to be caused by this....

William R. Lorenz wrote:

>Fellow Hibernaters,
>
>I'm receiving an Exception in a Hibernate application I've built, and I'm
>a bit confused as to why this might be happening.  The code at where the
>Exception is thrown is quite simple, and I think this might be a bug in
>Hibernate itself.  I've searched Google for this to no avail, and I'm
>using the latest recommended Hibernate release as available on the site.
>
>The exception I receive has a stacktrace as follows:
>
> java.util.ConcurrentModificationException
>  at java.util.AbstractList$Itr.checkForComodification(Unknown Source)
>  at java.util.AbstractList$Itr.remove(Unknown Source)
>  at net.sf.hibernate.impl.SessionImpl.executeAll(SessionImpl.java:2101)
>  at net.sf.hibernate.impl.SessionImpl.execute(SessionImpl.java:2061)
>  at net.sf.hibernate.impl.SessionImpl.flush(SessionImpl.java:2005)
>  at net.sf.hibernate.transaction.JDBCTransaction.commit(
>       JDBCTransaction.java:57
>     )
>  at org.express.ftpsrv.ConnectionHandler.<init>(ConnectionHandler.java:72)
>  at org.express.ftpsrv.ConnectionListener.accept(ConnectionListener.java:56)
>  at org.express.ftpsrv.ConnectionListener.main(ConnectionListener.java:19)
>
>And the code at ConnectionHandler.java:72 that causes this looks like:
>
>  52:this.ftpSession = new FtpSession();
>  53:
>  54:/* ftpSession.setSessionId() does not operate on the unique
>  55: * 'id' field that is also part of the ftpSession object.
>  56: */
>  57:ftpSession.setSessionId(UniqueGenerator.makeUniqueNumber());
>  58:
>  59:Date currentDate = new Date();
>  60:currentDate.setTime(System.currentTimeMillis());
>  61:this.ftpSession.setBegTime(currentDate);
>  62:
>  63:net.sf.hibernate.Session hSession = null;
>  64:Transaction transaction = null;
>  65:
>  66:try
>  67:{
>  68:  hSession = SessionHolder.getSession();
>  69:
>  70:  transaction = hSession.beginTransaction();
>  71:  hSession.save(this.session);
>  72:  transaction.commit();
>  73:} catch (HibernateException e)
>  74:{
>  75:  transaction.rollback();
>  76:}
>
>I'd like to point out that this seems to be an intermittent thing,
>occurring more often when I instantiate many objects quickly (the quoted
>lines 52-72, above, are within a cronstructor in the Object).
>
>Does anyone have any ideas as to what might be happening or where I might
>look for additional information in order to track down this bug?
>
>Thanks, in advance, for any response on this.
>
>--          _ 
>__ __ ___ _| | William R. Lorenz <wr...@ex...> 
>\ V  V / '_| | http://www.clevelandlug.net/ ; "Every revolution was 
> \./\./|_| |_| first a thought in one man's mind." - Ralph Waldo Emerson 
>
>
>
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