Ironic how other projects have driven out Singletons from their code - was it PHP Symphony or something like that? Anyway, all things in their place.
On 13 March 2013 14:32, Howard W. Smith, Jr. <smithh032...@gmail.com> wrote: > Interesting conversation/facts/etc... here! > > singleton is basically the model that 'spring' propagated for years? wow > (shaking my head)... I purposely have avoided being or becoming a 'spring' > user and said to myself, Java EE 6 (reference implementation) clearly is > sufficient to meet any/all my Java EE needs. :) > > anyway, i am using @Singleton more and more in my app...thanks to advice > given by David Blevins months ago. :) > > > On Wed, Mar 13, 2013 at 4:46 AM, Romain Manni-Bucau > <rmannibu...@gmail.com>wrote: > > > was no more clear for me ;) > > > > singleton is basically the model spring propagated for years and which is > > now known as very efficient > > > > > > *Romain Manni-Bucau* > > *Twitter: @rmannibucau <https://twitter.com/rmannibucau>* > > *Blog: **http://rmannibucau.wordpress.com/*< > > http://rmannibucau.wordpress.com/> > > *LinkedIn: **http://fr.linkedin.com/in/rmannibucau* > > *Github: https://github.com/rmannibucau* > > > > > > > > 2013/3/13 Jean-Louis MONTEIRO <jeano...@gmail.com> > > > > > I agree Romain, but it only works in that specific situation: > > > - EM type=TRANSACTION (not Extended) > > > - Java EE environment (not Java SE) > > > > > > And I also agree using a Singleton bean makes both true as it's not > > allowed > > > as per the spec to obtain an Extended PC in a Singleton. > > > > > > My purpose was just to try to get things clearer. > > > > > > Jean-Louis > > > > > > > > > 2013/3/13 Romain Manni-Bucau <rmannibu...@gmail.com> > > > > > > > Em is clearly thread safe in a javaee envrt in transaction mode...at > > > least > > > > because of the transaction constraint you can get the same instance > in > > > > different threads > > > > Le 13 mars 2013 08:40, "Jean-Louis MONTEIRO" <jeano...@gmail.com> a > > > écrit > > > > : > > > > > > > > > As a pure user feedback, we've been using OpenEJB/TomEE stateless > > beans > > > > on > > > > > huge applications and it does not produce any significant > > > > > nor noticeable overhead as soon as the pool size is well set up. > > > > > > > > > > So i'm really confident. > > > > > That said, the way singleton works with a READ lock is better in > lots > > > of > > > > > cases (no instances to manage, no locks in the pool, less memory > > > > > consumption, etc). > > > > > > > > > > But you are also right, it does not apply in any cases, I mean > using > > > > > stateless session beans is still relevant in some situations. Even > > if I > > > > > tend to preferably use Singleton, it's sometimes not applicable. > > > > > > > > > > Moreover you are right, EM is not thread safe as per the spec even > if > > > > some > > > > > implementations (Hibernate for example) are in some situations. We > > > > > discussed that point recently in the expert group as far as I > recall. > > > > > > > > > > Hope it helps, > > > > > Jean-Louis > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > 2013/3/13 zeeman <hamz...@fastmail.us> > > > > > > > > > > > I have to disagree with some of the gurus here. In most cases a > > > > stateless > > > > > > or > > > > > > singleton bean is going to use an entityManager/hibernate session > > to > > > > get > > > > > > data to/from the DB. EM is not thread safe, using a singleton > with > > > read > > > > > > lock > > > > > > will cause concurrency issues on EM. So stateless in that case is > > the > > > > way > > > > > > to > > > > > > go as it'll have its own EM instance. For scalable applications > > this > > > > > would > > > > > > work well. > > > > > > > > > > > > Having strict pooling = false with proper max/min values (based > on > > > > > expected > > > > > > app load) will work as suggested. > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > > > View this message in context: > > > > > > > > > > > > > > > > > > > > > http://openejb.979440.n4.nabble.com/ConcurrentAccessTimeoutException-tp4661288p4661466.html > > > > > > Sent from the OpenEJB User mailing list archive at Nabble.com. > > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > > Jean-Louis > > > > > > > > > > > > > > > > > > > > > -- > > > Jean-Louis > > > > > >
