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Old 06-27-2008, 08:14 AM
Mike Konstant Mike Konstant is offline
Join Date: Jun 2008
Posts: 5
Question fps performance caused by garbage collection?

Dear Vizard Users,

I am a new user to this group so appoligize in advance if I break protocol.

I am running a virtual reality simulation under Vizard Development Edition 101-89172709 Version 3.00.2701. The simulation works fine most of the time however once and a while the frame rate drops from 60fps down to 20-30ftps with no direct association with the users actions. Has anyone experience such intermittent performance? Can anyone suggest what approach should be taken to trackdown such a problem? More details of what I am facing is given below, for anyone interested;

The computer system is a NVIDIA NFORCE 680i LT SLI Intel Pentium III (2GB RAM) motherboard with a GeForce 8800 GTX card.

The python program running the simulation is multi-threaded. The simulation has static and dynamic objects in the environment. Below is a description of some testing I performed.
Test 1.
Ran simulator from IDE without the dynamic objects; no fps problem
Ran simulator from IDE with the dynamic objects; fps problem after 5 min
Test 2.
Repeated Test 1. Same results
Test 3.
Reset computer
Repeated Test 1. Same results.
Test 4.
Repeated Test 1, but also
Ran simulator from IDE again with the dynamic objects; no fps problem
Test 5.
Ran simulator from ouside IDE without dynamic objects; no fps problem
Ran simulator from ouside IDE with dynamic objects; no fps problem

As illustrated above, replicating this problem is a challenge and I can only guess that it may be cause by memory problems and perhaps related to garbage collection? Could this be a hardware issue? Any insight related to such symptoms would be greatly appreciated.

My current course of action is to eliminate portions of the simulator code until I get a configuration where the fps never drop. I hope I'm lucky and isolate the rogue code responsible for consuming the CPU time and causing the frame rate to underperform. (By the way, I have tried changing the vizard.exe priority to real-time, that just crashes the simiulator)

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