Hi Mark, On Apr 4, 2011, at 11:20 PM, Mark Wardle wrote:
> Hi all, > > There have been a number of threads discussing this runtime option. I > think the consensus opinion was that although it is off by default, it > is better switched on. I think it is off by default to match the previous (now ancient) functionality. > Presumably there are some basic additional rules to follow. The EOF Commandments (as usual) plus: Don't Do Stupid Things > For instance, AFAIK components will not be shared by multiple threads > as they will be instantiated as one goes along or will be returned > from the page cache as part of a single session - and as one session > will be handled by only one thread, this is fine. How does concurrent > handling interact with stateful and stateless components? Stateful are always session specific so safe by design. Stateless are also safe, transparently, see Practical WebObjects for the details if you want. > Perhaps more of an issue is that code within my EOF classes may be > executed by more than one thread at a time. I use lazy initialisation > but there is a race condition there. Fortunately, most of the time > there are no side-effects and running that code twice would have no > significant deleterious effect. For situations where it would matter I > would assume protecting lazy initialisation with a double check and a > synchronised block for the inner check would be fine? Is that > interpretation correct? I think that synchronised is what you want. > Are there other commandments? Don't Do Stupid Things :-) Which boils down to don't share objects that are not thread-safe, or writable data, at the global level unless you have appropriate protection. Global being either static members or instance variables on your application. Shared, non-thread safe formatters are a common mistake. Chuck -- Chuck Hill Senior Consultant / VP Development Practical WebObjects - for developers who want to increase their overall knowledge of WebObjects or who are trying to solve specific problems. http://www.global-village.net/products/practical_webobjects
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