Re: [Springframework-developer] Potentialt dangerous hibernate Session reuse

[Nick M. <nic...@gm...>]

>> Hence, one web request will quickly
>> use many connections, at the same time.

How so? Why should there be more than one session for a given request?

-Nick

On Mon, 14 Feb 2005 16:36:19 +0100, Per Olesen <po...@no...> wrote:
> Hi Juergen,
> 
> Thank you for your comments.
> 
> On Monday 14 February 2005 16:13, Juergen Hoeller wrote:
> >
> > I am aware of the Hibernate docs that the Session needs to be discarded
> > when an exception was thrown. However, I find that an overly strict
> > statement (just like "there is no such thing as a non-transactional
> > Session", their famous statement from their forums mid last year).
> 
> Okay, i tend to agree about it being an overly strict statement, also because
> I've looked into SessionImpl.clear() and it does what we want :-) ... but:
> When they've explicitly stated that a Session should not be reused in case of
> exception, upcoming implementations of Session might break spring then. Can
> it not?
> 
> > Session.clear should be good enough for resetting an OSIV Session after a
> > rollback. It's probably advisable to not use OSIV in single session mode at
> > all if you want to avoid side effects completely. (Closing the Session and
> > opening a new one during OSIV doesn't really add value here.)
> 
> It will add the value that:
>  1) the failing session is thrown away
>  2) new calls into spring-managed beans will operate fine on the new session
> 
> I know, that lazy-loading of objects from dead session will fail.
> 
> > Have you considered using OpenSessionInViewFilter in "deferred close mode",
> > that is, with the "singleSession" flag turned off? In that case, each
> > transaction will use its own Hibernate Session, but all of those Sessions
> > will be kept open until view rendering has completed.
> 
> Yes, actually I have tried it out. But this solution does not scale very well.
> A JDBC connection is assigned to each hibernate Session, so using deferred
> close uses a connection for each session. Hence, one web request will quickly
> use many connections, at the same time.
> 
> Per
> 
> --
> Per Olesen @ Nordija A/S - www.nordija.com - main#: +45 70 20 25 10
> email: po...@no... - cell#: +45 23 38 95 81
> 
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