Memory leak in Swing

Question

An application Swing (GUI), a destination a destination information terminal. The VirtualVM profiler shows that the leakage occurs due to

java.awt.image.DataBufferInt

и

sun.awt.image.ImageRepresentation.setPixels

, the increase of memory occurs during transitions between forms.

The application logic is that there are several forms (JFrame - JF1, JF2 ... JF7). JF1 basic form, pressing the JButtons open other forms, and closes itself, etc. Except JF1 all other forms have buttons <>. In forms there are many JButtons with the pictures, used FancyButton:

public class FancyButton extends JButton {
    private static final long serialVersionUID = 1L;

    public FancyButton(Icon icon, Icon pressed) {
        super(icon);
        setFocusPainted(false);
        //setRolloverEnabled(treue);
        //setRolloverIcon(rollover);
        setPressedIcon(pressed);
        setBorderPainted(false);
        setContentAreaFilled(false);
    }
}

The JButtons on the forms are drawn as follows:

public class JF1 extends JFrame {

    private static final GridBagConstraints gbc;
    public static Timer tmr;

    public JF1() throws Exception{
        setUndecorated(true);
        GraphicsEnvironment.getLocalGraphicsEnvironment().getDefaultScreenDevice().setFullScreenWindow(this);
        setAlwaysOnTop(true);
        setLayout(new GridBagLayout());
        setTitle("JF1");
    }

    public void init() throws Exception{

        GlobalVars.jf2 = null;
        GlobalVars.jf3 = null;
        GlobalVars.jf4 = null;
        GlobalVars.jf5 = null;
        GlobalVars.jf6 = null;
        GlobalVars.jf7 = null;
        JXPanel contentPane = new JXPanel();
                try {
                ImagePainter ip = new ImagePainter(ImageIO.read(new File("skins/bg.jpg")));
                ip.setFillHorizontal(true);
                ip.setFillVertical(true);
                contentPane.setBackgroundPainter(ip);
             } catch (Exception e) {
                e.printStackTrace();
             }


        Panel p01 = new Panel();
        GridLayout gl01 = new GridLayout(1, 8, 2, 2);
        p01.setLayout(gl01);
        p01.setLocation(200, 300);
        ResultSet rs = GlobalVars.st.executeQuery("select * from last_use_service order by nomer");
        Icon i1;
        Icon i2;
        while (rs.next()){
            final int l = rs.getInt(2);
            i1 = new ImageIcon("skins/oper_logos/" + l + ".png");
            i2 = new ImageIcon("skins/oper_logos/" + l + "_off.png");

            FancyButton jbt = new FancyButton(i1,i2 );
            jbt.setBounds(10, 100, 100, 100);

            jbt.addActionListener(new ActionListener() {
                public void actionPerformed(ActionEvent event) {
                    tmr.stop();     

                    if(GlobalVars.jf3==null)
                                            GlobalVars.jf3 = new JF3();
                    GlobalVars.jf3.init(); 
                    GlobalVars.jf3.setVisible(true);            // Так открывается новая форма
                    setVisible(false);                              // и закрывается текущая
                    dispose();
                }
            });
            p01.add(jbt);
        }
        rs.close();
        addComponent(panel, p01, 0, 1, 2, 1, GridBagConstraints.WEST,GridBagConstraints.NORTHWEST);
...

The main class which starts first:

public class Main {

    public static class GlobalVars{

        public static String TypeDB = "MySQL";  
        public static Connection DataBase;
        public static Statement st;     

        public static JF1 jf1;          // JFrame
        public static JF2 jf2;          // JFrame
        public static JF3 jf3;          // JFrame
        ...
    }

    public static void main(String[] args) throws Exception {
        if(GlobalVars.TypeDB.equals("MySQL")){
            Class.forName("com.mysql.jdbc.Driver");
            GlobalVars.DataBase = DriverManager.getConnection("jdbc:mysql://localhost:3306/terminal?lc_ctype=UTF8", "root","123");

                if(GlobalVars.jf1==null)
                    GlobalVars.jf1 = new JF1();
        GlobalVars.jf1.init();
        GlobalVars.jf1.setVisible(true);
        }
...
       }

Still in Init method of Forms has a timer which, after a time, opens the main form and closes the current one:

...
tmr = new Timer( s * 1000, updateCursorAction);
tmr.start();
...
private Action updateCursorAction = new AbstractAction() {
        public void actionPerformed(ActionEvent e) {
            if(GlobalVars.jf1==null){
                try {
                    GlobalVars.jf1= new JF1();
                } catch (Exception e1) {
                    e1.printStackTrace();
                }
            }
            tmr.stop();
            try {
                GlobalVars.jf1.init();
            } catch (Exception e1) {
                e1.printStackTrace();
            }
            GlobalVars.jf1.setVisible(true);
            GlobalVars.jf2 = null;
            setVisible(false);
            dispose();      
        }
    };

HEAP DUMP Please help fix a memory leak.

I had changed all Panel to JPanel and that is code of JF1:

package PlatService;

import java.awt.*;

public class JF1 extends JFrame {
    private static final long serialVersionUID = 1L;
    //private static final Insets insets = new Insets(0, 0, 0, 0);
    private static String[] arrLang = { "rus", "eng", "taj" };
    private static final GridBagConstraints gbc;
    public static Timer tmr;

    static {

    public JF1() throws Exception{
        setUndecorated(true);
        GraphicsEnvironment.getLocalGraphicsEnvironment().getDefaultScreenDevice().setFullScreenWindow(this);
        setAlwaysOnTop(true);
        setLayout(new GridBagLayout());
        setTitle("JF1");
    }

    public void init() throws Exception{

        GlobalVars.jf2 = null;
        GlobalVars.jf3 = null;
        GlobalVars.jf4 = null;
        GlobalVars.jf5 = null;
        GlobalVars.jf6 = null;
        GlobalVars.jf7 = null;
        JXPanel contentPane = new JXPanel();
        try {
                ImagePainter ip = new ImagePainter(ImageIO.read(new File("skins/bg.jpg")));
                ip.setFillHorizontal(true);
                ip.setFillVertical(true);
                contentPane.setBackgroundPainter(ip);
        } catch (Exception e) {
                e.printStackTrace();
        }
        //setContentPane(contentPane);
        JPanel panel = new JPanel();
        panel.setLayout(new GridBagLayout());
        addComponent(this, panel, 0, 0, 1, 1, GridBagConstraints.CENTER ,GridBagConstraints.BOTH);

        JPanel p0 = new JPanel();
        GridLayout gl0 = new GridLayout(1, 1, 1, 1);
        final JLabel jl = new JLabel(new ImageIcon("skins/logo.png"));
        p0.setLayout(gl0);
        p0.add(jl);
        addComponent(panel, p0, 0, 0, 2, 1, GridBagConstraints.NORTH ,GridBagConstraints.NORTH);


        JPanel p01 = new JPanel();
        GridLayout gl01 = new GridLayout(1, 8, 2, 2);
        p01.setLayout(gl01);
        p01.setLocation(200, 300);
        ResultSet rs = GlobalVars.st.executeQuery("select * from last_use_service order by nomer");
        Icon i1;
        Icon i2;
        while (rs.next()){
            final int l = rs.getInt(2);
            i1 = new ImageIcon("skins/oper_logos/" + l + ".png");
            i2 = new ImageIcon("skins/oper_logos/" + l + "_off.png");
            FancyButton jbt = new FancyButton(i1,i2 );
            jbt.setBounds(10, 100, 100, 100);
            jbt.addActionListener(new ActionListener() {
                public void actionPerformed(ActionEvent event) {
                    tmr.stop();
                    GlobalVars.OperId = l;
                    GlobalVars.getCashCode=false;
                    if(GlobalVars.jf3==null)GlobalVars.jf3 = new JF3();
                    GlobalVars.jf3.init(); // = new JF3();
                    GlobalVars.jf3.setVisible(true);
                    setVisible(false);
                    dispose();
                }
            });
            p01.add(jbt);
        }
        rs.close();
        addComponent(panel, p01, 0, 1, 2, 1, GridBagConstraints.WEST,GridBagConstraints.NORTHWEST);

        if (GlobalVars.LangId < 0 || GlobalVars.LangId > 2)GlobalVars.LangId = 0;

        String sql = "SELECT * FROM OpGroup WHERE parent=0 order by enable desc, order_n";
        PreparedStatement psmnt = GlobalVars.DataBase.prepareStatement(sql);
        ResultSet rs2 = psmnt.executeQuery();

        //rs = GlobalVars.st.executeQuery();
        JPanel p = new JPanel();
        GridLayout gl = new GridLayout(0, 2, 2, 2);
        p.setLayout(gl);
        p.setSize(300, 400);
        p.setLocation(200, 300);        
        while (rs2.next()){
            final int l = rs2.getInt(2);
            i1 = new ImageIcon("skins/"+ arrLang[GlobalVars.LangId]+"/services/" + l + ".png");
            i2 = new ImageIcon("skins/"+ arrLang[GlobalVars.LangId]+"/services/" + l + "_off.png");
            FancyButton jbt = new FancyButton(i1,i2);
            jbt.setBounds(10, 100, 100, 100);
            if(rs2.getInt("enable")==1){
                jbt.setEnabled(true);
            }else{
                jbt.setEnabled(false);
            }
            jbt.addActionListener(new ActionListener() {
                public void actionPerformed(ActionEvent event) {
                    GlobalVars.getCashCode=false;
                    try {
                        tmr.stop();
                        ActionPerformed(event, GlobalVars.LangId, l);
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
            });
            p.add(jbt);
        }
        addComponent(panel, p, 0, 2, 1, 1, GridBagConstraints.NORTH,GridBagConstraints.NORTH);
        rs2.close();
        JPanel p1 = new JPanel();
        GridLayout gl1 = new GridLayout(5, 1, 5, 5);
        // setLayout(new GridLayout(3, 4, 2, 2));
        p1.setLayout(gl1);
        // p2.setSize(300, 400);
        // p2.setLocation(200, 300);

        for (int i = 0; i < arrLang.length; i++) {
            final int l = i;
            i1 = new ImageIcon("skins/button_" + arrLang[i] + ".png");
            i2 = new ImageIcon("skins/button_" + arrLang[i] + "_off.png");
            FancyButton jbt = new FancyButton(i1, i2);
            jbt.setBounds(10, 100, 100, 100);
            //if (i == GlobalVars.LangId) {jbt.setEnabled(false);}
            jbt.addActionListener(new ActionListener() {
                public void actionPerformed(ActionEvent event) {
                    //Play.stop();
                    GlobalVars.LangId = l;
                    GlobalVars.getCashCode=false;
                    GlobalVars.jf1 = null;
                    try {
                        GlobalVars.jf1 = new JF1();
                    } catch (Exception e1) {
                        e1.printStackTrace();
                    }
                    try {
                        GlobalVars.jf1.init();
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                    tmr.stop();
                    GlobalVars.jf1.setVisible(true);
                    setVisible(false);
                }
            });
            p1.add(jbt);
        }
        i1 = new ImageIcon("skins/" + arrLang[GlobalVars.LangId] + "/services/button_help.png");
        i2 = new ImageIcon("skins/" + arrLang[GlobalVars.LangId] + "/services/button_help_off.png");
        FancyButton jbt_help = new FancyButton(i1,i2);
        jbt_help.setBounds(10, 100, 100, 100);
        jbt_help.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent event) {
                tmr.stop();
                GlobalVars.getCashCode=false;
                GlobalVars.jf1 = null;
                try {
                    GlobalVars.jf1 = new JF1();
                } catch (Exception e1) {
                    e1.printStackTrace();
                }
                try {
                    GlobalVars.jf1.init();
                } catch (Exception e) {
                    e.printStackTrace();
                }
                GlobalVars.jf1.setVisible(true);
                setVisible(false);
            }
        });
        p1.add(jbt_help);
        i1 = new ImageIcon("skins/" + arrLang[GlobalVars.LangId] + "/services/button_about.png");
        i2 = new ImageIcon("skins/" + arrLang[GlobalVars.LangId] + "/services/button_about_off.png");
        FancyButton jbt_about = new FancyButton(i1,i2);
        jbt_about.setBounds(10, 100, 100, 100);

        p1.add(jbt_about);
        addComponent(panel, p1, 1, 2, 1, 1, GridBagConstraints.EAST,GridBagConstraints.EAST);

        JPanel p011 = new JPanel();
        GridLayout gl011 = new GridLayout( 1, 1, 1, 1);
        gl011.setVgap(1);
        JLabel jl12 = new JLabel("<html><hr></html>", JLabel.LEFT);
        jl12.setAlignmentX(TOP_ALIGNMENT);
        jl12.setBackground(Color.red);
        p011.setLayout(gl011);
        p011.add(jl12);
        p011.setSize(10, 90);
        addComponent(panel, p011, 0, 3, 4, 1, GridBagConstraints.WEST, GridBagConstraints.NORTH);


        JPanel p0112 = new JPanel();
        GridLayout gl0112 = new GridLayout( 1, 1, 1, 1);
        gl0112.setVgap(1);
        JLabel jl122 = new JLabel("<html><hr><H2>"+GlobalVars.StatusMessage[GlobalVars.LangId]+"</H2></html>", JLabel.CENTER);
        jl122.setAlignmentX(TOP_ALIGNMENT);
        p0112.setLayout(gl0112);
        p0112.add(jl122);
        p0112.setSize(10, 90);

        addComponent(this, p0112, 0, 5, 5, 1, GridBagConstraints.SOUTH, GridBagConstraints.BOTH);

        if(!GlobalVars.stTerminal.equals("301")){
            GlobalVars.stTerminal = "301";
            String sql1 = "INSERT INTO perif_status (perif,state,date_change) values('terminal','"+GlobalVars.stTerminal+"',UNIX_TIMESTAMP())";
            //System.out.println(sql1);
            try {
                GlobalVars.st.execute(sql1);
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        GlobalVars.NomerAb="";
        GlobalVars.GroupId = 0;
        GlobalVars.getCashCode=true;
        tmr = new Timer(1000, updateCursorAction);
        tmr.start();

        System.gc();
    }

    public void update(){

    private Action updateCursorAction = new AbstractAction() {
        public void actionPerformed(ActionEvent e) {
            if(GlobalVars.doBlock){
                if(!GlobalVars.stTerminal.equals("303")){
                    GlobalVars.stTerminal = "303";
                    String sql1 = "INSERT INTO perif_status (perif,state,date_change) values('terminal','"+GlobalVars.stTerminal+"',UNIX_TIMESTAMP())";
                    String sql2 = "UPDATE settings set value='"+GlobalVars.stTerminal+"' WHERE variable='terminal_state'";
                    System.out.println(sql1);
                    System.out.println(sql2);
                    try {
                        GlobalVars.st.execute(sql1);
                    } catch (SQLException e1) {
                        e1.printStackTrace();
                    }
                    try {
                        GlobalVars.st.execute(sql2);
                    } catch (SQLException e1) {
                        e1.printStackTrace();
                    }
                }       
                String sql1 = "UPDATE commands SET status=1, date_execute=UNIX_TIMESTAMP() WHERE id_on_server="+GlobalVars.doCommandId;
                System.out.println(sql1);
                try {
                    GlobalVars.st.execute(sql1);
                } catch (SQLException e1) {
                    e1.printStackTrace();
                }
                if(GlobalVars.jf7==null)
                    try {
                        GlobalVars.jf7= new JF7();
                    } catch (Exception e1) {
                        e1.printStackTrace();
                    }
                try {
                    GlobalVars.jf7.init();
                } catch (Exception e1) {
                    e1.printStackTrace();
                }


                GlobalVars.doBlock=false;
                GlobalVars.doCommandId = 0;
                GlobalVars.jf7.setVisible(true);
                GlobalVars.jf1 = null;
                setVisible(false);
                tmr.stop();
                setVisible(false);
                dispose();
            }
        }
    };

    private static void addComponent(Container container, Component component,int gridx, int gridy, int gridwidth, int gridheight, int anchor,int fill) {
        Insets ins = new Insets(0, 0, 0, 0); 
        GridBagConstraints gbc1 = new GridBagConstraints(gridx, gridy,gridwidth, gridheight, 1.0, 1.0, anchor, fill, ins, 0, 0);
        container.add(component, gbc1);
    }

    public void ActionPerformed(ActionEvent event, int lID,int gId) throws Exception {
        GlobalVars.GroupId = gId;
        if(GlobalVars.jf2==null)GlobalVars.jf2 = new JF2();
        GlobalVars.jf2.init(); 
        GlobalVars.jf2.setVisible(true);
        setVisible(false);
        dispose();
    }
}

And thats new dump

Answer 1

You do have a leak, but just looking at the number of loaded classes will not help you to find out what it is.

If you load your snapshot in JProfiler (disclaimer: my company develops JProfiler) and look at the biggest objects view, you can see that used memory is due to the double buffering of multiple JF1 frames and the panel instances that belong to those frames.

Your problem is that the JF1 frames are hidden but not disposed. A search for GC roots shows that all 3 invisible frames are contained in java.awt.Window.allWindows which cannot the case if dispose() is called. You call a lot of code outside the event dispatch thread. For example you should not call setVisible() from the timer thread. Try printing out the creation of JF1 frames and the call to their dispose methods and check where the do not they match.

Answer 2

you create lots of Top-level Containers, with JComponents or Images inside them, and these Objects in this form never gone for JVM Used_Memory, you have to clean-up contents of un-used Top-level Containers,

better would be

create JFrame only once, and for another popup windows create only one JDialog/JWindow put here JPanel, re-use this Container by removing JComponents from JPanel,

JPanel.removeAll();

DefaultCloseOperation would be

JDialog#setDefaultCloseOperation(JDialog.HIDE_ON_CLOSE)

or you can set

JDialog#setDefaultCloseOperation(JDialog.DO_NOTHING_ON_CLOSE) and then you can call only

JDialog#setVisible(false / true)

EDIT

and you have to close all JDBC ResultSet, Statement, PreparedStatement in finally block, because these Object never gone from JVM UsedMemory too