Memory Leak (may be) in Java 2D

Question

Hi,
I am using a Java in an application that continuously reads data from a source and draws them on the screen. Everything runs fine as long as I stick to basic lines for drawing the graphs and it does not matter how many windows of the application is open. As soon as I start using dashed lines using BasicStroke - it starts consuming memory at a ridiculous rate (goes from 20M to 100M in about 20 seconds). Any idea where this leak might be coming from and how to fix this ? I have tried using dispose () all over the place but has not worked so far. Even System.gc() everytime in the paintComponent() of the the JPanel doing all the painting does not seem to do much good.
Thanks in advance to anyone who replies.
-Hassan.

Answer 1

Here is a more concrete example of what I am talking about - try running the following example with and without the g2.setStroke() line in method NewPanel.paintComponent() commented out and look at the memory usage and speed:
import java.io.*;
import java.awt.*;
import java.awt.geom.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.*;
import java.io.*;
import java.util.*;
public class TestMU extends JFrame {
public TestMU(){
     super();
addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
          System.exit(0);
     getContentPane().add(new NewPanel());
public static void main (String argv []){
     TestMU gu = new TestMU();
gu.setSize(new Dimension(550,700));
gu.setVisible(true);
class NewPanel extends JPanel{
public NewPanel(){
     super();
public void paintComponent(Graphics g){
     super.paintComponent(g);
     int i;
     float dash1[] = {1.0f};
     BasicStroke bs = new BasicStroke(.5f, BasicStroke.CAP_BUTT,
                         BasicStroke.JOIN_MITER, 1f, dash1, 0.0f);
     Graphics2D g2 = (Graphics2D)g;
     // This line right here!!!
// Try it with and without the g2.setStroke() line
     g2.setStroke(bs);
     for (i=1;i<20000;i++){
     g2.drawLine(20,30,i,30);
     if (i%100 == 0) System.err.println(i);
Memory usage goes from around 19 MB to 60 MB and repainting speed goes from about 2 seconds to a minute (or more) when the line is uncommented.
Does anyone know what additional stuff java might be storing and doing that's causing the increase in memory usage and such drastic reduction in speed ?
-Hassan