[hibernate-dev] [ORM] Synchronization on AbstractLoadPlanBasedLoader

[Steve Ebersole]

I'm confused.  Sanne was talking about a completely different piece of code
from optimizers.  Maybe you are mixing this and the other current
hibernate-dev discussion?


On Mon, Dec 14, 2015 at 11:10 AM Vlad Mihalcea <mihalcea.vlad at gmail.com>
wrote:

> Hi,
>
> We really need to test it thoroughly because the current pooled optimizer
> are reasonably fast especially when used with a database sequence.
> The table generators are slow because of the row-level locking, so I won't
> include those in this discussion.
>
> What strikes me is the synchronized block which might cause contention we
> didn't have before.
> I'd also vote for a new optimizer instead of modifying the pooled or the
> pooled-lo ones.
> The current optimizer are quite easy to grasp, and, if we are to add a
> high-performance one, I think a new implementation is better suited for
> this task.
>
> Vlad
>
> On Mon, Dec 14, 2015 at 6:25 PM, Sanne Grinovero <sanne at hibernate.org>
> wrote:
>
> > Hi all,
> > while reviewing an improvement by Stale about reducing
> > synchronization, I'm having the impression that the synchronization
> > could be completely removed.
> >
> > But there's a comment warning me against that, so for sake of safety
> > I'm merging the improvement without risking going too far:
> >
> >  // synchronized to avoid multi-thread access issues; defined as
> > method synch to avoid
> >  // potential deadlock issues due to nature of code.
> >
> > I tried to figure what "potential deadlock" it's referring to, but I'm
> > having the impression the comment might be outdated. So I've reduced
> > the contention to the only include the code block about which I'm not
> > confident.
> > By looking into git history, it seems the comment isn't related to any
> > specific fix but was included already when this class was first
> > created.
> >
> > Would someone be able to point out what is the issue this is protecting
> > against?
> >
> > That should allow us to provide an even better patch, although I'll
> > apply the safe one for now so to at least have the benefits already
> > when wrapping of result-sets is disabled.
> >
> > thanks,
> > Sanne
> > _______________________________________________
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> >
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