Here's the best I could do on how to write singletons: http://developer.java.sun.com/developer/technicalArticles/Programming/single tons/
On the locking front, I can't find anything that suggests that the semantics of volatile have been changed to make double-checked locking work. I'd love to hear different, or if anyone is aware of anything upcoming to make the issue more obvious/go away... > -----Original Message----- > From: Felipe Schnack [mailto:[EMAIL PROTECTED]] > Sent: 05 February 2003 12:06 > To: [EMAIL PROTECTED]; Tomcat Users List > Subject: RE: singleton creation (ot) > > > Hmm... nice links! > The first one said about a proposal of solving this problem through > the use of "volatile" keyword... this was implemented in jdk 1.4? It > seems that site is older than this release... > I'm not sure yet of how I will do it... I would not like to > synchronize the entire method because it'll probably be called million > of times in my app > > On Wed, 2003-02-05 at 09:42, Daniel Brown wrote: > > The simple answer is 'no'. > > > > For the more complex answer, read the 'Double-Checked Locking is Broken' > > declaration at: > > > > http://www.cs.umd.edu/~pugh/java/memoryModel/DoubleCheckedLocking.html > > > > To complicate matters even further, check out the JavaDoc to the Fast* > > utilities in the Jakarta commons. For example: > > > > > http://jakarta.apache.org/commons/collections/api/org/apache/commo > ns/collect > > ions/FastTreeMap.html > > > > (apologies for the wrap). > > > > Dan. > > > > > -----Original Message----- > > > From: Felipe Schnack [mailto:[EMAIL PROTECTED]] > > > Sent: 05 February 2003 11:21 > > > To: Tomcat Users List > > > Subject: singleton creation (ot) > > > > > > > > > I was wondering... this code is valid to avoid excessive use of > > > synchronized code? I think so, but we never know :-) > > > This is the default getInstance() method of a singleton > (simplified): > > > > > > public Object getInstance() > > > { > > > if (INSTANCE == null) > > > { > > > synchronized (this) > > > { > > > if (INSTANCE == null) > > > { > > > INSTANCE = this.getClass().newInstance(); > > > } > > > } > > > } > > > return INSTANCE; > > > } > > > > > > -- > > > > > > Felipe Schnack > > > Analista de Sistemas > > > [EMAIL PROTECTED] > > > Cel.: (51)91287530 > > > Linux Counter #281893 > > > > > > Centro Universit�rio Ritter dos Reis > > > http://www.ritterdosreis.br > > > [EMAIL PROTECTED] > > > Fone/Fax.: (51)32303341 > > > > > > > > > --------------------------------------------------------------------- > > > To unsubscribe, e-mail: [EMAIL PROTECTED] > > > For additional commands, e-mail: [EMAIL PROTECTED] > > > > > > > > > --------------------------------------------------------------------- > > To unsubscribe, e-mail: [EMAIL PROTECTED] > > For additional commands, e-mail: [EMAIL PROTECTED] > > > -- > > Felipe Schnack > Analista de Sistemas > [EMAIL PROTECTED] > Cel.: (51)91287530 > Linux Counter #281893 > > Centro Universit�rio Ritter dos Reis > http://www.ritterdosreis.br > [EMAIL PROTECTED] > Fone/Fax.: (51)32303341 > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
