I've experienced loss of singleton's under heavy load. We used an object preserver as detailed by Mark Grand in 'Patterns in Java' to register the singleton with a permanently waiting thread.
The other option is to use of statics is to specify the JVM option of -Xnoclassgc to stop class collection. Regards Richard > -----Original Message----- > From: Adolfo Miguelez [mailto:[EMAIL PROTECTED] > Sent: Wednesday, August 27, 2003 11:04 AM > To: [EMAIL PROTECTED] > Subject: Re: Is singleton DAO acceptable? -- Best Practices > > > Check out this link for some info about this topic. We tested > under WAS 5, > and its JDK should be 1.3.1 or something like that. Actually > the JDK that > comes which WAS 5. > > http://www.javaworld.com/javaworld/javatips/jw-javatip52.html > > It was curious because after a good perfomance, above certain > stress load, > singleton looks like to dissapear and app begin to throw errors..... > > Can not tell you how to solve it since our solution was > refactoring code and > removing the singleton. Perhaps referencing from somewhere, > ServletContext > or a struts plugin could help. Maybe someone could help more > accuracily, > > Adolfo. > > >From: Mick Wever <[EMAIL PROTECTED]> > >Reply-To: "Struts Users Mailing List" > <[EMAIL PROTECTED]> > >To: [EMAIL PROTECTED] > >Subject: Re: Is singleton DAO acceptable? -- Best Practices > >Date: Wed, 27 Aug 2003 10:43:55 +0200 > > > >On Tue, 26 Aug 2003 20:10:07 +0000, Adolfo Miguelez wrote: > > > Just to share my experience with singletons: under heavy > stress we found > > > that a singleton class in our framework was garbage > collected. As far as > >I > > > remember, singletons are eligible for that with current > SDKs despite > >policy > > > has changed over times as I read from some document in the web. > > > > > > They were eligible for GC if its ClassLoader is GCd and > they are not > > > referenced by any object... or something like that. > Please check for > > > accuracy. > > > >This is very interesting. Which SDK implementation did you see this > >behavour? > > > >The single reference to the DAO is actually inside the > DAOFactory not the > >DAO itself (hence it is not a traditional Singleton) so > hopefully this > >will prevent the scenerio of it being GC'd. > >Or will I have to go further and reference it inside a > Struts context as > >well? (Eg use the Struts plugin mechanism). > > > >Mick. > > > > > >--------------------------------------------------------------------- > >To unsubscribe, e-mail: [EMAIL PROTECTED] > >For additional commands, e-mail: [EMAIL PROTECTED] > > > > _________________________________________________________________ > Tired of spam? Get advanced junk mail protection with MSN 8. > http://join.msn.com/?page=features/junkmail > > --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
