I've a little test here to demonstrate the problem.
Obviously the code works but as you increase the thread count (assuming there are enough cores) performance does not improve.
It's as if drawing operations are serialised.
import java.awt.*;
import java.awt.image.BufferedImage;
import java.util.Date;
import java.util.Random;
public class Para2dTest {
class DrawSomething implements Runnable {
@Override
public void run() {
Random r = new Random();
long start = new Date().getTime();
BufferedImage image = new BufferedImage( 100, 100, BufferedImage.TYPE_INT_ARGB );
Graphics2D g2d = image.createGraphics();
for ( int i = 0; i < 100000; i++ ) {
Color c = new Color( r.nextInt(256), r.nextInt(256), r.nextInt(256) );
g2d.setPaint(c);
g2d.fillRect( 0, 0, 100, 100 );
}
g2d.dispose();
long end = new Date().getTime();
System.out.println( Thread.currentThread().getName() + " " + ( end - start ) );
}
}
public Para2dTest( int threads ) {
for ( int t = 0; t < threads; t++ ) {
Thread ds = new Thread( new DrawSomething() );
ds.start();
}
}
public static void main(String[] args) {
System.setProperty("java.awt.headless", "true");
int threads = 16;
if (args.length > 0) {
try {
threads = Integer.parseInt(args[0]);
System.out.println("Processing with " + threads + " threads");
} catch (NumberFormatException e) {
System.err.println("Argument" + " must be an integer");
}
}
new Para2dTest( threads );
}
}
