[hibernate-dev] Hibernate Developer IRC meeting - 5/03

Steve Ebersole steve at hibernate.org
Thu May 3 13:32:21 EDT 2012

I seriously doubt the performance cost of 20 'parallel arrays' versus 1 
array of Objects holding those 20 values is anything but negligible at 

On Thu 03 May 2012 11:04:30 AM CDT, Emmanuel Bernard wrote:
> Sorry I could not assist the meeting live but reviewed the logs and had some remarks, so ehre are the logs and my remarks :)
> ## Meeting logs
> http://transcripts.jboss.org/meeting/irc.freenode.org/hibernate-dev/2012/hibernate-dev.2012-05-03-14.01.html
> Minutes (text):http://transcripts.jboss.org/meeting/irc.freenode.org/hibernate-dev/2012/hibernate-dev.2012-05-03-14.01.txt
> Log:            http://transcripts.jboss.org/meeting/irc.freenode.org/hibernate-dev/2012/hibernate-dev.2012-05-03-14.01.log.html
> ## About parallel arrays vs arrays of objects
> Even today, there is a cost in using Objects or HashMap as data placeholders. This might not be relevant for us especially since we are not using them for "live" data but since memory footprint has always been a concern for Hibernate, it's worth mentioning.
> This presentation is quite interesting and show the extra memory cost of such structure compared to arrays http://www.cs.virginia.edu/kim/publicity/pldi09tutorials/memory-efficient-java-tutorial.pdf
> ## PessimisticLockException versus LockAcquisitionException
> I am not certain of that and Git history got cut short with the migration of entitymanager into core. But I do have recollections of some lock exceptions that were not catch up and I had to use PessimisticLockException. It could have been a change triggered by the TCK. Again I might be wrong, it was a long time ago. Plus ORM's core has evolved since.
> Emmanuel
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steve at hibernate.org

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