Peter B. West wrote: > Please indulge my ignorance again. May I assume that it is not possible > to run two main()s in the same VM?
Not in the sense you probably mean. > From this discussion so far I have gained much more insight into the > nervousness about statics. Is the problem that servers want to execute > multiple instances of classes within the one VM? Are there other problems? The problem is multiple threads accessing static class data, which is really global. Well, the standard scenario is: There are multiple threads sleeping while waiting for requests. One thread wakes up, sets the FOP baseDir, creates a Driver instqance and starts rendering. Just before the thread is about to resolve an URI for an external graphic, it is suspended and another thread gets a chance to run, it reads its request, sets the global baseDir to soemthing else, and is itself suspended in favour for the first thread, which reads the now changed value for baseDir from the configuration, and explodes. It doesn't help to make the Driver methods synchronized, because there are two instances of the driver object :-( you would have to lock the global configuration data so that the second thread would have to wait until the first finishes processing. Of course, this nullifies the advantages of using multithreading, especially on MP machines. I like the approach JAXP did for transformers. You have a factory where you can set default stuff so that you don't have to do this every time an individual processor is created, and you can override settings on the individual instances. The individual processor instances never access global data after creation. Does this answer your question(s)? J.Pietschmann --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, email: [EMAIL PROTECTED]
