Well, I am not a Terracotta pro. But have at least a little bit of experience with it. But I think the problem could be true for the same for other clustering solutions, too.
Terracotta is able to keep object identity within different clustered VMs. It is necessary to define root objects that are shared over the cluster. All referenced objects are shared too. So if a root contains a references to a DateTime object, that object is transferred to the other VMs. But as I see, each DateTime object holds some references to DateTimeFieldType. Those are transfered too. But of course those objects are not the same as the objects that are stored within the static fields of the class DateTimeFieldType. Now there exist three approaches to solve that issue: - Don't compare objects using ==. I know that this is not perfect, but for me it was a very simple solution... But ok, I think that is not the way to go. - Share the static fields: I tried this successfully. But of course the performance is very, very poor. Every time a static field of DateTimeFieldType is accessed, that field is locked in the hole cluster. So obviously this is not a possible solution. - Reinitializing the date time objects: It is possible to call methods or execute bean shell code, when an object is transferred to another VM. Can you tell me a way how those references could be updated to the correct one? I think it is necessary to reinitialize all fields that are compared using == with the values stored in the static fields. If that is possible, everything should work as expected. And since DateTime is Serializable I think there might be a way... I think that Joda is a great API (thanks for your work). And I think that Terracotta is a great product, too. I would like to see them work together. Maybe it is possible for one of the Joda gurus to mail directly with one of the Terracotty guys? I may convey... I have also created a small sample application that can be used to test several solutions. If necessary, I will improve that and help to detect problems. Regards, Johannes Schneider On Thu, 2008-03-27 at 16:31 +0000, Stephen Colebourne wrote: > There are lots of places in Joda-Time where we rely on == rather than > .equals(). This patch certainly won't be sufficient to fix all those > places. > > In order to change Joda-Time to solve an issue like this I would need > proof (eg. someone from Terracotta) saying that this cannot be fixed > by a change in the Terracotta setup. Basically, comparing objects > using == is a fundamental Java concept, and a tool like Terracotta > really needs to support it. > > Stephen > > > On 26/03/2008, Johannes Schneider <[EMAIL PROTECTED]> wrote: > > Okay, > > > > I have created a small patch that seems to fix my problems. It can be > > downloaded at > > http://cedarsoft.de/tmp/terracotta_compatibility_patch.patch > > > > I am not sure whether that is enough for terracotta support, but for me > > it works so far. > > And I don't understand whether I have added a pitfall to Joda time. > > > > The problem is that > > org.joda.time.base.AbstractPartial#compareTo > > compares the field types using "!=" but when using a cluster those > > instances are not identical. > > So I have added a simple "equals" method to > > org.joda.time.DateTimeFieldType.StandardDateTimeFieldType. > > > > > > At the moment I use that patched version successfully. It would be great > > if anyone could take a look at that patch and give some comments whether > > that is a valid change that could be added to the trunk. > > ------------------------------------------------------------------------- > Check out the new SourceForge.net Marketplace. > It's the best place to buy or sell services for > just about anything Open Source. > http://ad.doubleclick.net/clk;164216239;13503038;w?http://sf.net/marketplace > _______________________________________________ > Joda-interest mailing list > Joda-interest@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/joda-interest -- Johannes Schneider Im Lindenwasen 15 72810 Gomaringen Fon +49 7072 9229972 Fax +49 7072 509999 Mobil +49 178 1364488 [EMAIL PROTECTED] http://www.johannes-schneider.info
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