[fervus]

Hello!
I am working on a J2ME game with MIDP2 and m3g.
My midlet starts more than one Thread which contains a canvase. When I exit one canvas, I stop the thread (return from it's main loop) and then I start a new Thread width a new canvas to take me to the next screen of the game. However, I noticed that the device (tested on Nokia N95) doesn't free the memory for the old thread and eventually runs out of mem.
Calling System.gc doesn't help. The wierd thing is that the emulator from SUN DOES free the memory, but not the Nokia Device:

Here is a bit of my code:

baseCanvas.exitThread();
baseCanvas=null;
baseThread=null;
System.gc();

battleCanvas = new BattleCanvas3D(this);
battleCanvas.setCommandListener(this);
battleCanvas.addCommand(exitCommand);
battleCanvas.addCommand(baseCommand);
battleThread=new Thread(battleCanvas);
battleThread.start();


where exitThread() contains:
exit=true;
and the run() method of BattleCanvas contains:
do {
if (exit) {
return;
}
.....
}

So... in this example I would like to free all the memory occupied by baseThread(baseCanvas). It does so on the emulator from SUN but not on the Nokia implementation.

Can you help me solve this problem?
Am I doing something wrong?
Thanks!

[grahamhughes]

My first suggestions (for anyone writing a MIDP game):

Use only one Canvas. Switching between Displayable objects causes problems if you want to detect when your game is interrupted by an incoming call.

Create only one Thread. Multiple threads will make your life a nightmare.

So, create one Canvas instance and one Thread when the application starts, then keep them.

As to your memory leaks... are you dumping and re-loading 3D models? Or creating models dynamically? Series 60 implementations have problems garbage collecting 3D models, and tend to leak.

Load or create each model only once, and keep it.

[fervus]

Originally Posted by grahamhughes

My first suggestions (for anyone writing a MIDP game):

Use only one Canvas. Switching between Displayable objects causes problems if you want to detect when your game is interrupted by an incoming call.

Create only one Thread. Multiple threads will make your life a nightmare.

So, create one Canvas instance and one Thread when the application starts, then keep them.

As to your memory leaks... are you dumping and re-loading 3D models? Or creating models dynamically? Series 60 implementations have problems garbage collecting 3D models, and tend to leak.

Load or create each model only once, and keep it.

Yes, thank you!
I'll try that! The only problem is that every module fit in about 7-8 MB. If I preload all of them, I'll need about 15 MB. I was hoping to do with less.
Still, thank you for your reply.

[grahamhughes]

You might have to do with less.

Reduce the number of polygons in each model (this will increase performance too). This is a little outside my expertise, but I think there are tools that will optimize models by merging triangles into triangle-strips... this also reduces size and increases performance. Have a look around for different converters/exporters.

[rdrincon]

One more suggestion

Once a variable or object is no longer used, reference it to null, this will help much more than calling System.gc ;)