Some additional thoughts before going to bed: - I think the static synchronized WeakHashMap should be avoided. There's a lot of synchronization that is performed. I suspect this will have a bad effect on performance. It may make more sense to have a FlyWeightFactory (per object) per rendering run. Somebody (don't remember who, sorry) wrote that FOP cannot bring the CPU to 100%, probably due to synchronization issues. Could be worth investigating since this would mean we give away CPU cicles here. - It's probably not the most effective way to use the Property itself as the key into the Map, i.e. creating throw-away instances excessively. Working with specialized FlyWeightFactories could be more efficient. See http://en.wikipedia.org/wiki/Flyweight_pattern - One of the easiest candidates for another flyweight is probably CommonHyphenation (56K instances, 2.3MB in my example). The few member variables could probably just be concatenated to a String (to be used as the key). - It could be worth looking into the difference between HashMap and TreeMap. Maybe one is more suitable than the other. I haven't looked at the difference, yet.
Jeremias Maerki
