You can only see the true object usage if you run your JVM in debug mode and use a product like http://www.jprofiler.com to analyze it.
FusionReactor can however give you some insight via it's memory graphs. If you set the memory sampling to 100ms and run only your request on the server, you will get a pretty good image of memory usage from your function.
|Components:||CPU + Memory|
|Last Updated:||20/Jun/07 4:19 PM|