Question

I have a Java 3D program which uses lots (hundreds) of 3D models (3ds and obj).
The more models I use (and I really, really have to, it’s kind of 3D model of the real world object) the more heavier the program becomes, till the point when any single operation takes ages to complete.

CPU consumption rarely reaches 50%, mostly is moving between 10%-30%, but memory consumption is growing (obviously) with each added 3D model.

I know how to minimize memory imprint of c++/ c programs, but with Java’s GC is there anything I can do about it except increasing the JVM’s memory with -Xmx? I am already running with -xMx512Mb.

I have checked GC logs, using GCViewer, didn’t find anything suspicious.

I am aware of some very similar questions on SO, but none answered my question exactly.

My IDE is IntelliJ 11.

Answer 1

There are two simple ways to decrease the number of objects you are creating, and one or both of them may work for your purposes, though without specifications I can’t be sure.

1) Work with highly mutable objects. If you need to simulate a large number of things with a great deal of similarity, but which don’t have to interact with each other (for example, a hundred thousand simulations of a dozen particles interacting, with slightly different particles each time), then using the same dozen or so objects over and over, and making use of mutator functions to transfer the burden to the CPU. However, I doubt that using many objects in sequence is a problem for you, given that Java already has built-in garbage collection.

2) Make the similarities between similar objects their own class. For example, if you have the need for a lot of objects, and you notice that a significant proportion of them share a number of memory-intensive characteristics, store those characteristics in their own class and refer to a single instance of that class in every object with the exact same field values. As an example, consider a set of Apple objects. You could either create different classes for GrannySmithApples, MackintoshApples, RedDeliciousApples with their own static fields for characteristics shared across the class (e.g. RedDeliciousApples have a static String field declared in the abstract class Apple and set to “red”), or (to allow more flexibility at runtime) each class could have an instance of CoreCharacteristic. If multiple objects share the same core characteristics, the code:

CoreCharacteristic c = new CoreCharacteristic(<some parameters>);
Apple apple1 = new Apple(c);
Apple apple2 = new Apple(c);
Apple apple3 = new Apple(c);
Apple apple4 = new Apple(c);

will use only one CoreCharacteristic for all four apples, quartering the amount of memory needed to store the fields of CoreCharacteristic which would have otherwise been replicated for each Apple.