Memory leak with Swing application

My application uses more and more memory as I use it. However, if it is working like I think, it is not creating more objects and has no reason to use more memory. When the application is minimized a lot of that memory is freed up. Does anyone know what is the cause of this? I have a sneaking suspicion that it is somehow related to my swingworkers. Also, if it is an error with my code how do I use the netbeans profiler to find the cause? I have just used the profiler for the first time - all I really can tell is that it seems to consume more and more memory.

To answer a comment earlier in this thread, of course
the jvm is doing garbage collection - that's the way
java works. Nobody said otherwise. What was said was that the JVM doesn't necessarily release the memory. Just because the object has been collected doesn't mean the JVM is going to give it back to the OS.
As I understand, when you do System.gc()
this is apparently just a hint to the jvm to do
garbage collection. To quote the api:
"Calling the gc method suggests that the Java
Virtual Machine expend effort toward recycling
unused objects in order to make the memory they
currently occupy available for quick reuse."Which is irrelevant. Furthermore, this thread is almost a year old.

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                             case 8 :
                                  return "+";
                             default :
                                  return null;

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                        public void actionPerformed(java.awt.event.ActionEvent e) {
                             for (int i = 0; i < 50; i++) {
                                  TestDialog td = new TestDialog();
                                  td.show();
                                  td.close_advanced();
                             System.gc();
              return jB_showandclose_advanced;
          * @param args
         public static void main(String[] args) {
              // TODO Auto-generated method stub
              TestRAMUsage application = new TestRAMUsage();
              application.show();
          * This is the default constructor
         public TestRAMUsage() {
              super();
              initialize();
          * This method initializes this
          * @return void
         private void initialize() {
              this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
              this.setJMenuBar(getJJMenuBar());
              this.setSize(300, 200);
              this.setContentPane(getJContentPane());
              this.setTitle("Application");
          * This method initializes jContentPane
          * @return javax.swing.JPanel
         private JPanel getJContentPane() {
              if (jContentPane == null) {
                   jContentPane = new JPanel();
                   jContentPane.setLayout(null);
                   jContentPane.add(getJB_showandclose_normal(), null);
                   jContentPane.add(getJB_showandclose_advanced(), null);
              return jContentPane;
          * This method initializes jJMenuBar     
          * @return javax.swing.JMenuBar     
         private JMenuBar getJJMenuBar() {
              if (jJMenuBar == null) {
                   jJMenuBar = new JMenuBar();
                   jJMenuBar.add(getFileMenu());
              return jJMenuBar;
          * This method initializes jMenu     
          * @return javax.swing.JMenu     
         private JMenu getFileMenu() {
              if (fileMenu == null) {
                   fileMenu = new JMenu();
                   fileMenu.setText("File");
                   fileMenu.add(getExitMenuItem());
              return fileMenu;
          * This method initializes jMenuItem     
          * @return javax.swing.JMenuItem     
         private JMenuItem getExitMenuItem() {
              if (exitMenuItem == null) {
                   exitMenuItem = new JMenuItem();
                   exitMenuItem.setText("Exit");
                   exitMenuItem.addActionListener(new ActionListener() {
                        public void actionPerformed(ActionEvent e) {
                             System.exit(0);
              return exitMenuItem;
    import javax.swing.JButton;
    import javax.swing.JDialog;
    import javax.swing.JPanel;
    import javax.swing.JTextField;
    public class TestDialog extends JDialog {
         private static final long serialVersionUID = -4326706771573368209L;
         private JPanel jContentPane = null;
         private JButton jB_drucken = null;
         private JTextField jTF_hallo = null;
         private JButton jB_close = null;
          * This is the default constructor
         public TestDialog() {
              super();
              initialize();
          * This method initializes this
          * @return void
         private void initialize() {
              this.setSize(541, 255);
              this.setTitle("Speicher Dialog");
              this.setContentPane(getJContentPane());
          * This method initializes jContentPane
          * @return javax.swing.JPanel
         private JPanel getJContentPane() {
              if (jContentPane == null) {
                   jContentPane = new JPanel();
                   jContentPane.setLayout(null);
                   jContentPane.add(getJB_drucken(), null);
                   jContentPane.add(getJTF_hallo(), null);
                   jContentPane.add(getJB_close(), null);
              return jContentPane;
          * This method initializes jB_drucken
          * @return javax.swing.JButton
         private JButton getJB_drucken() {
              if (jB_drucken == null) {
                   jB_drucken = new JButton();
                   jB_drucken.setBounds(new java.awt.Rectangle(45, 88, 211, 19));
                   jB_drucken.setText("Sag Hallo Welt");
              return jB_drucken;
          * This method initializes jTF_hallo
          * @return javax.swing.JTextField
         private JTextField getJTF_hallo() {
              if (jTF_hallo == null) {
                   jTF_hallo = new JTextField();
                   jTF_hallo.setBounds(new java.awt.Rectangle(269, 88, 228, 19));
              return jTF_hallo;
          * This method initializes jB_close
          * @return javax.swing.JButton
         private JButton getJB_close() {
              if (jB_close == null) {
                   jB_close = new JButton();
                   jB_close.setBounds(new java.awt.Rectangle(196, 179, 109, 22));
                   jB_close.setText("Schlie�en");
                   jB_close.addActionListener(new java.awt.event.ActionListener() {
                        public void actionPerformed(java.awt.event.ActionEvent e) {
                             try {
                                  // setVisible(false);
                                  dispose();
                                  removeAll();
                                  // getContentPane().removeAll();
                                  // finalize();
                             } catch (Throwable e1) {
                                  // TODO Auto-generated catch block
                                  e1.printStackTrace();
              return jB_close;
          * Dispose the Dialog
         public void close_normal() {
              dispose();
          * Set all Variables to null
          * Remove all Container
          * dispose the Dialog
          * and finalize it!
         public void close_advanced() {
              // System.out.println(this.);
              dispose();
              // show();
              jContentPane = null;
              jB_drucken = null;
              jTF_hallo = null;
              jB_close = null;
              getContentPane().removeAll();
              removeAll();
              try {
                   finalize();
              } catch (Throwable e) {
                   // TODO Auto-generated catch block
                   e.printStackTrace();
    } // @jve:decl-index=0:visual-constraint="10,10"

    I have use Methods in some Software Produkts. But if your Software
    use 30 MB in RAM the Runtime classes say 12 MB used. I don`t think
    that this works hereThe 12 MB is the memory used of the available 30 MB memory available. Once the VM get its memory from the OS, it does not have to return the memory back to the OS right away.
    By calling System.gc() does nt guarentee the garbage collector to be activated right away. you are just asking the garbage collector to run when it get a chance. Since the emeory is not near the max memory available...the gc is likely not going to run. Futhermore, if your application is running..the gc is likely wont run, unless memory is needed when you reach the max limit.
    because the user want to view at more than one Dialog at the same
    timeunderstandable..i just hope the 50 dialogs is just for testing the memory. i can't imagine any user would want to open 50 dialog at the same time =)
    And the other is, that the Variables in the Dialog class wouldn`t clean
    in RAM (that was the reason to set all to null!)why would it not be? When you dispose the dialog, the object will be null out..so when the garbage collector kick in, it will reclaim the memory. Now, if you have references to object in the dialog, that reference will be null out as well..the object may still exist (by having another live object having a reference to it)...the garbage collector would reclaim the dialog memory..but not the "live" object that the dialog has reference to.
    I ran the application..testing both button.
    The top button..there were little memory consumption..the second button consume a little memory bit-by-bit. I see no memory leak here. What happens is you called GC() 50 times..but it will only run one time when it get a chance...by nulling out the variables, and calling finalize()..it actually slow down the garbage collecting...that's why you should not even obther with having those two method. Furthermore, finalize method may not even be called.
    Memory leak occurs when you have a reference from an object still hanging around, but that object is no longer needed. This is a design issue.
    example
    public class A{
        Item item = new Item();
        public void getItem(){ return item; };
    public class B{
        Item item;
        public B(A a){
            item = a.getItem();
    A a = new A();
    B b = new B(a);
    a = null;when a is null out..the item reference is null, but the actual object still exist and 'b' has a reference to it. so by nulling out those object does not mean you just got rid of the object. it's better to let the object scope run out..and the garbage collector to collect it.. When you null out the object, you could accidentally null out an object that some other object may be using.

  • Memory Leak with new Font()

    Hello all,
    Not sure if this is the right place to post this but here goes. I have a program that needs to change the font of at least 250,000 letters, however after doing this the program runs slow and laggy as if changing the fonts of each letter took up memory and never released it? Here is a compilable example, Click the button at the bottom of the window and watch the letter it is currently working on. You will notice that around 200,000 it will begin to not smoothly count up anymore but count in kind of a skipping pattern. This seems to get worse the more you do it and seems to indicate to me that something is using memory and not releasing it. I'm not sure why replacing a letter's font with a new font would cause more memory to be taken up I would think if I was doing it properly it would simply replace the old font with the new one not taking anymore memory then it did before. Here is the example: This program sometimes locks up so be prepared. If someone could maybe point out what is causing this to take up more memory after changing the fonts that would be great and hopefully find a solution :) Thanks in advance.
    -neptune692
    * To change this template, choose Tools | Templates
    * and open the template in the editor.
    package paintsurface;
    import java.awt.*;
    import java.awt.event.*;
    import javax.swing.*;
    import java.util.*;
    import java.util.List;
    public class PaintSurface implements Runnable, ActionListener {
    public static void main(String[] args) {
            SwingUtilities.invokeLater(new PaintSurface());
    List<StringState> states = new ArrayList<StringState>();
    Tableaux tableaux;
    Random random = new Random();
    Font font = new Font("Arial",Font.PLAIN,15);
    //        Point mouselocation = new Point(0,0);
    static final int WIDTH = 1000;
    static final int HEIGHT = 1000;
    JFrame frame = new JFrame();
    JButton add;
    public void run() {
            tableaux = new Tableaux();
            for (int i=250000; --i>=0;)
                    addRandom();
            frame.add(tableaux, BorderLayout.CENTER);
            add = new JButton("Change Font of letters - memory leak?");
            add.addActionListener(this);
            frame.add(add, BorderLayout.SOUTH);
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            frame.setSize(WIDTH, HEIGHT);
            frame.setLocationRelativeTo(null);
            frame.setVisible(true);
    public void actionPerformed(ActionEvent e) {
        new Thread(new ChangeFonts()).start();
    void addRandom() {
            tableaux.add(
                            Character.toString((char)('a'+random.nextInt(26))),
                            UIManager.getFont("Button.font"),
                            random.nextInt(WIDTH), random.nextInt(HEIGHT));
    //THIS CLASS SEEMS TO HAVE SOME KIND OF MEMORY LEAK I'M NOT SURE?
    class ChangeFonts implements Runnable {
        public void run() {
        Random rand = new Random();
            for(int i = 0; i<states.size(); i++) {
                font = new Font("Arial",Font.PLAIN,rand.nextInt(50));
                states.get(i).font = font;
                add.setText("Working on letter - "+i);
    class StringState extends Rectangle {
            StringState(String str, Font font, int x, int y, int w, int h) {
                    super(x, y, w, h);
                    string = str;
                    this.font = font;
            String string;
            Font font;
    class Tableaux extends JComponent {
            Tableaux() {
                    this.enableEvents(MouseEvent.MOUSE_MOTION_EVENT_MASK);
                    lagState = createState("Lag", new Font("Arial",Font.BOLD,20), 0, 0);
            protected void processMouseMotionEvent(MouseEvent e) {
                    repaint(lagState);
                    lagState.setLocation(e.getX(), e.getY());
                    repaint(lagState);
                    super.processMouseMotionEvent(e);
            StringState lagState;
            StringState createState(String str, Font font, int x, int y) {
                FontMetrics metrics = getFontMetrics(font);
                int w = metrics.stringWidth(str);
                int h = metrics.getHeight();
                return new StringState(str, font, x, y-metrics.getAscent(), w, h);
            public void add(String str, Font font, int x, int y) {
                    StringState state = createState(str, font, x, y);
                    states.add(state);
                    repaint(state);
            protected void paintComponent(Graphics g) {
                    Rectangle clip = g.getClipBounds();
                    FontMetrics metrics = g.getFontMetrics();
                    for (StringState state : states) {
                            if (state.intersects(clip)) {
                                    if (!state.font.equals(g.getFont())) {
                                            g.setFont(state.font);
                                            metrics = g.getFontMetrics();
                                    g.drawString(state.string, state.x, state.y+metrics.getAscent());
                    if (lagState.intersects(clip)) {
                    g.setColor(Color.red);
                    if (!lagState.font.equals(g.getFont())) {
                        g.setFont(lagState.font);
                        metrics = g.getFontMetrics();
                    g.drawString("Lag", lagState.x, lagState.y+metrics.getAscent());
    }Here is the block of code that I think is causing the problem:
    //THIS CLASS SEEMS TO HAVE SOME KIND OF MEMORY LEAK I'M NOT SURE?
    class ChangeFonts implements Runnable {
        public void run() {
        Random rand = new Random();
            for(int i = 0; i<states.size(); i++) {
                font = new Font("Arial",Font.PLAIN,rand.nextInt(50));
                states.get(i).font = font; // this line seems to cause the problem?
                add.setText("Working on letter - "+i);
    }

    neptune692 wrote:
    jverd wrote:
    You're creating a quarter million distinct Font objects, and obviously you must be hanging on to all of them because each character is having its font set to the newly created object. So if you have 250k chars, you're forcing it to have 250k Font objects.
    Since the only difference is that rand.nextInt(50) parameter, just pre-create 50 Font objects with 0..49, stick 'em in the corresponding elements in an array, and use rand.nextInt to select the Font object to use.That does make sense but it does that when the the program is first launched and doesn't lag. But the second and third time you change the letters font it seems to lag so if it wasn't taking up more memory the second time it should perform like it did when it first launched. I don't care to investigate any further. The real problem is almost certainly the quarter million Font objects. It could be that 250k is fine, but by the time you get to 500k, it has to do a lot of GC, and that's where the slow down is coming. You might even be able to make it work better with the code you have just by tweaking the GC parameters at startup, but I wouldn't bother. Fix the code first, and then see if you have issues.
    Does creating a new font for each of those letters not replace the old font object? If it didn't use more memory the second and third time I don't think you would see the skipping in the counter and the slowing down of the iterations. So it must be remembering some of the old font objects or am I wrong?Using new always creates a new object. When you do it the second time around, and call letter.setFont(newFont), the old Font object is eligible for GC. That doesn't mean it will be GCed right away though. The JVM can leave them all laying around until it runs out of memory, and then GC some or all of them.

  • Memory Leak with 4.5.1/Java/Solaris

    Hi,
    We are currently running a Java Application using RMI/Weblogic 4.5.1/Solaris 5.7/Java 1.22.
    Behavior that has been observered during the day is that memory usage reaches a stage in which it begins increasing and GC doesn't recover any memory, until the heap reaches an extremly large size, then recovers a significant amount of memory.
    We have even seen the java process grab more memory than specified in the -Xmx parameter and experience a java.lang.OutOfMemory error.
    I have seen postings that describe similar issues in this newsgroup, but none that define a solution.
    This problem is intermittent, and our application can run an entire day without experiencing this memory leak. On the other hand there are days when the memory leak occurrs even when the system is idle overnight.
    Please let me know any information you have gathered on this subject.
    Regards,
    Mark Evans

    try increasing your virtual memory on your NT system...
    "Parasher K. Joshi" <[email protected]> wrote:
    >
    Hi,
    I observed the same confusing stuff in my tests. But I run weblogic 4.5.1 on Windows NT with JDK 1.2.2-w
    Usually, I would get a "Low virtual memory" message from windows
    and if I click ok & shuffle thourgh my windows I would be ok.
    But since last 2 days, I would keep the server running overnight.
    When I return in morning,
    I would find a "Low virtual memory" message and
    on clicking OK. I would find another message tell me that java.exe (which was running weblogic) crashed!!
    Now today I tried to watch the memory usage in Task Manager. And I found the most wierd thing.
    I saw that even when the system was doing virtually nothing,
    except print a string at intervals, the memory usage would go
    up steadyly.
    Even doing a forced finalization and gc did not seem to stop it.
    BUT, BY CHANCE I HAPPEN TO MINIMISE AND MAXIMISE THE WEBLOGIC
    CONSOLE OUTPUT WINDOW.
    WHAT I SAW IN THE TASK MANAGER AMAZED ME!
    THE MEMORY USAGE IN TASK MANAGER HAD GONE DOWN TO 24XXKB, WHILE
    IT WAS ABOUT 20000K OR EVEN MORE.
    This seems to support the fact that during my test, I would
    get the "low virtual memory" message and if OKed it and shuffled
    though application windows (maybe minimise, maximise the weblogic
    console output window in process), I would be able to complete
    my application. But when the message appears during night runs,
    nothing is done and by morning, when I reach to work,
    I would see that weblogic had crashed!!
    You may try that and see if it helps you.
    Parasher
    Mark Evans <[email protected]> wrote:
    Hi,
    We are currently running a Java Application using RMI/Weblogic 4.5.1/Solaris 5.7/Java 1.22.
    Behavior that has been observered during the day is that memory usage reaches a stage in which it begins increasing and GC doesn't recover any memory, until the heap reaches an extremly large size, then recovers a significant amount of memory.
    We have even seen the java process grab more memory than specified in the -Xmx parameter and experience a java.lang.OutOfMemory error.
    I have seen postings that describe similar issues in this newsgroup, but none that define a solution.
    This problem is intermittent, and our application can run an entire day without experiencing this memory leak. On the other hand there are days when the memory leak occurrs even when the system is idle overnight.
    Please let me know any information you have gathered on this subject.
    Regards,
    Mark Evans

  • Memory Leak with Weblogic 6.1

    Hello everyone.
    I need some help with a problem we are having with our application. It consists on Servlets, JMS with MDBs, Xml parsing...
    Our application dequeues messages from an Oracle Queue and sends xml-text message to a servlet. It also receives xml-text and enqueues objects in an Oracle Queue.
    And it also has access to Oracle Database (context tables, etc).
    We are doing everything on Tru64 Unix (and our tests on Win 2000) and we are using WebLogic 6.1.
    Our problem is that we have found that it seems that the garbage collector is not running well. I mean, with the time our system is degrading. The memory use increases. It seems to be a memory leak.
    We have used a testing tool, OptimizeIt, and we have found that there are
    objects that are increasing the use of memory. If we use the option 'java -verbose' we find that it seems to be Hash objects (HashMap, Hashtable) which are increasing the use of memory. In our code we are not using any hashtable nor any class that extends from it (we have deleted everyone).
    Can it be due to a problem with WebLogic? A problem with JMS, queues, etc? A problem with JNDI?
    Could anybody please help us?
    Thanks in advanced.

    Yes, we see that there are some entries of the type:
    java/util/Hahstable$Entry
    java/util/Hahstable
    weblogic/jndi/Environment
    This entries keep growing and growing with the time.
    We have deleted all the Hashtable, Properties and all the kind of Collection objects. I guess WebLogic is using this objects in order to arrange our application runs.
    Am I right? Do you know if we can do anything?
    Thank you.

  • Memory leak with File Write.vi

    Hi All,
    I am trying to save a big data cluster, which includes images, into a data log file. The vis I use are: New File.vi, Write File.vi, Close File.vi.
    The problem is Write File.vi has memory leak  when the data cluster includes images .
    Anyone sees similar case?  Any solution?
    Thanks.
    Aiqiu

    Aiqiu,
    I am glad you found out about flattening your image to a string.  I was about to post and say that you probably didn't want to save the IMAQ image reference to a file, because after you closed the image in memory, there wouldn't be anything for the IMAQ image reference to point to.  You are correct to flatten the image to a string.  Below is a link to a document which discusses doing this to communicate over datasocket, but the processes of flattening the image to a string is the same regardless of whether or not you are sending the image across a datasocket connection or saving to a file.
    Transfering Images with DataSocket
    As for the memory leak.  I am pretty sure that if you passed all of the IMAQ Image references created in the "Image Init Buffer.vi" subVI and then closed each reference individually, that the memory leak would probably go away.
    Lorne Hengst
    Application Engineer
    National Instruments

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