MultiResolutionToolkitImage.ObserverCache memory leak

MrImageObserverLeakTest.java

package net.example.swing;

import java.awt.BasicStroke;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Component;
import java.awt.Container;
import java.awt.Font;
import java.awt.FontMetrics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.LayoutManager;
import java.awt.RenderingHints;
import java.awt.event.ActionEvent;
import java.awt.image.BufferedImage;
import java.awt.image.ImageObserver;
import java.lang.ref.Reference;
import java.lang.ref.ReferenceQueue;
import java.lang.ref.WeakReference;
import java.lang.reflect.InvocationTargetException;
import java.util.ArrayList;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;

import javax.swing.AbstractAction;
import javax.swing.Box;
import javax.swing.BoxLayout;
import javax.swing.DefaultListModel;
import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.JCheckBox;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JList;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JSplitPane;
import javax.swing.JTabbedPane;
import javax.swing.JToolBar;
import javax.swing.LookAndFeel;
import javax.swing.SwingUtilities;

/**
 * <em>Not an actual leak!</em> Soft references tend to stick around for much
 * longer than weak references, for example.  Try using VM arguments like:</p>
 * <pre>
 * -XX:SoftRefLRUPolicyMSPerMB=1 -Xmx64M</pre>
 * <p>
 * to cause soft references to be cleared faster.</p>
 *
 * @see  <a href="https://bugs.openjdk.java.net/browse/JDK-8257500">JDK-8257500 : Drawing MultiResolutionImage with ImageObserver leaks memory</a>
 * @see  <a href="https://bugs.openjdk.java.net/browse/JDK-8022449">JDK-8022449 : Can we get rid of sun.misc.SoftCache?</a>
 */
@SuppressWarnings("serial")
public class MrImageObserverLeakTest extends JFrame {

    DefaultListModel<Reference<Object>> liveObjects;
    ReferenceQueue<Object> queue = new ReferenceQueue<>();
    JTabbedPane tabs;
    JCheckBox workaroundDefault;
    JCheckBox workaroundDisabled;

    AbstractAction openTab = new AbstractAction("+Tab") {
        {
            super.putValue(SHORT_DESCRIPTION, "Open a New Tab (Ctrl+T)");
        }
        @Override public void actionPerformed(ActionEvent evt) {
            TabContent content = new TabContent(workaroundDefault.isSelected(),
                                                    workaroundDisabled.isSelected());
            tabs.addTab(content.getName(), null, content, "Ctrl+W to Close");
            liveObjects.addElement(new DebugReference(content, queue));
            if ((evt.getModifiers() & ActionEvent.SHIFT_MASK) == 0) {
                tabs.setSelectedIndex(tabs.getTabCount() - 1);
            }
        }
    };

    AbstractAction closeTab = new AbstractAction() {
        @Override
        public void actionPerformed(ActionEvent evt) {
            if ((evt.getModifiers() & ActionEvent.SHIFT_MASK) == 0) {
                int index = tabs.getSelectedIndex();
                if (index >= 0) tabs.removeTabAt(index);
            } else {
                tabs.removeAll();
            }
        }
    };

    public MrImageObserverLeakTest() {
        super("Multi-Resolution ImageObserver Leak Test");

        Container contentPane = super.getContentPane();
        contentPane.add(initToolBar(), BorderLayout.PAGE_START);
        contentPane.add(initMainPanel(), BorderLayout.CENTER);
    }

    private Component initToolBar() {
        JToolBar toolBar = new JToolBar();
        toolBar.setName("Tools");
        toolBar.setFloatable(false);
        toolBar.setRollover(true);

        toolBar.add(openTab);
        toolBar.add(new AbstractAction("GC") {
            {
                super.putValue(SHORT_DESCRIPTION, "Run the Garbage Collector (Ctrl+Click for Aggressive)");
            }
            @Override public void actionPerformed(ActionEvent evt) {
                if ((evt.getModifiers() & ActionEvent.CTRL_MASK) != 0) {
                    try {
                        // java.util.ArrayList.MAX_ARRAY_SIZE
                        // jdk.internal.util.ArraysSupport.MAX_ARRAY_LENGTH
                        final int maxArraySize = Integer.MAX_VALUE - 8;
                        final ArrayList<Object> temp = new ArrayList<>();
                        long freeBytes;
                        while ((freeBytes = Runtime.getRuntime().freeMemory()) > 0) {
                            int size = (int) Math.min(freeBytes, maxArraySize);
                            temp.add(new byte[size]);
                        }
                    } catch (OutOfMemoryError e) {
                        // -XX:SoftRefLRUPolicyMSPerMB=... Soft references are
                        // more likely to be cleared sooner at this point.
                    }
                }
                System.gc();
            }
        });

        toolBar.addSeparator();

        toolBar.add(new JLabel("Icon workaround:")).setEnabled(false);
        workaroundDefault = (JCheckBox) toolBar.add(new JCheckBox("\"Default\"", true));
        workaroundDefault.setOpaque(false);
        workaroundDisabled = (JCheckBox) toolBar.add(new JCheckBox("\"Disabled\"", true));
        workaroundDisabled.setOpaque(false);

        return toolBar;
    }

    private Component initMainPanel() {
        tabs = new JTabbedPane();
        tabs.setTabLayoutPolicy(JTabbedPane.SCROLL_TAB_LAYOUT);
        liveObjects = new DefaultListModel<>();
        JList<?> objectList = new JList<Reference<Object>>(liveObjects) {
            @Override public boolean getScrollableTracksViewportWidth() { return true; }
        };

        tabs.getActionMap().put("OpenTab", openTab);
        tabs.getActionMap().put("CloseTab", closeTab);
        LookAndFeel.loadKeyBindings(tabs.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW),
                                    new Object[] { "control T",       "OpenTab",
                                                   "control shift T", "OpenTab",
                                                   "control W",       "CloseTab",
                                                   "control shift W", "CloseTab" });

        JScrollPane listScroll = new JScrollPane(objectList);
        Box listPane = Box.createVerticalBox();
        JLabel listLabel = (JLabel) listPane.add(new JLabel("Live objects:"));
        listLabel.setLabelFor(listScroll);
        listScroll.setAlignmentX(LEFT_ALIGNMENT);
        listPane.add(listScroll);

        JSplitPane split = new JSplitPane(JSplitPane.VERTICAL_SPLIT, tabs, listPane);
        split.setResizeWeight(0.4);
        SwingUtilities.invokeLater(() -> split.setDividerLocation(0.4));
        return split;
    }

    void startPolling() {
        ScheduledExecutorService service = Executors.newScheduledThreadPool(1);
        Runnable pollQueue = () -> {
            try {
                Reference<?> ref;
                while ((ref = queue.poll()) != null) {
                    final Reference<?> refCapture = ref;
                    SwingUtilities.invokeAndWait(() -> {
                        int index = liveObjects.indexOf(refCapture);
                        assert (index >= 0);
                        liveObjects.removeElementAt(index);
                    });
                }
            } catch (InvocationTargetException e) {
                System.err.println(e);
            } catch (InterruptedException e) {
                System.err.println(e);
                Thread.currentThread().interrupt();
            } catch (OutOfMemoryError e) {
                // Try again next time
            }
        };
        service.scheduleAtFixedRate(pollQueue, 5, 1, TimeUnit.SECONDS);
    }

    public static void main(String[] args) throws Exception {
        SwingUtilities.invokeLater(() -> {
            // swing.defaultlaf, swing.metalTheme
            if (!System.getProperties().containsKey("swing.metalTheme")) {
                // The default Ocean doesn't have MultiResolutionImage
                // support with LookAndFeel.getDisabledIcon()
                System.setProperty("swing.metalTheme", "steel");
            }

            MrImageObserverLeakTest frame = new MrImageObserverLeakTest();
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            frame.pack();
            frame.setLocation(50, 50);
            frame.setVisible(true);
            frame.startPolling();
        });
    }


    static class TabContent extends JPanel {

        private static int count = 0;

        private final boolean workaroundDefault;
        private final boolean workaroundDisabled;

        TabContent(boolean workaroundDefault, boolean workaroundDisabled) {
            super((LayoutManager) null);
            super.setLayout(new BoxLayout(this, BoxLayout.LINE_AXIS));
            super.setName("#" + (count += 1));
            this.workaroundDefault = workaroundDefault;
            this.workaroundDisabled = workaroundDisabled;

            super.add(Box.createHorizontalGlue());

            ImageIcon defaultIcon = TestIcon.createMrIcon();
            if (workaroundDefault) {
                TestIcon.avoidMrLeak(defaultIcon);
            }
            super.add(new LeakedComponent(defaultIcon));
            super.add(Box.createHorizontalStrut(5));

            JLabel disabled = (JLabel) super.add(new LeakedComponent(defaultIcon));
            Icon disabledIcon = disabled.getDisabledIcon();
            if (workaroundDisabled) {
                TestIcon.avoidMrLeak(disabledIcon);
            }
            disabled.setEnabled(false);
            super.add(Box.createHorizontalGlue());
        }

        @Override
        protected String paramString() {
            return getName() + ", workaround: default=" + workaroundDefault + ", disabled=" + workaroundDisabled;
        }
    }


    static class DebugReference extends WeakReference<Object> {

        DebugReference(Object referent, ReferenceQueue<? super Object> q) {
            super(referent, q);
        }

        @Override
        public String toString() {
            Object t = get();
            if (t == null) {
                return "null";
            }
            return t.toString();
        }
    }


    static class DummyObserver implements ImageObserver {
        static final ImageObserver INSTANCE = new DummyObserver();
        @Override
        public boolean imageUpdate(Image img, int infoflags, int x, int y, int width, int height) {
            return false;
        }
    }


    static class TestIcon {

        static ImageIcon createMrIcon() {
            final int userWidth = 48;
            final int userHeight = 48;
            // Using Java-internal class just for test/demo purpose.
            Image mrImage = new sun.awt.image.MultiResolutionCachedImage(userWidth, userHeight,
                    (deviceWidth, deviceHeight) -> {
                BufferedImage variant = new BufferedImage(deviceWidth, deviceHeight, BufferedImage.TYPE_INT_ARGB);
                Graphics2D g = variant.createGraphics();
                g.scale((double) deviceWidth / userWidth, (double) deviceHeight / userHeight);
                g.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                                   RenderingHints.VALUE_ANTIALIAS_ON);
                g.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING,
                                   RenderingHints.VALUE_TEXT_ANTIALIAS_ON);

                final int padding = 2;
                g.setColor(Color.blue);
                g.fillOval(padding, padding, userWidth - 2 * padding, userHeight - 2 * padding);
                g.setColor(Color.white);
                g.setStroke(new BasicStroke(2));
                g.drawOval(padding, padding, userWidth - 2 * padding, userHeight - 2 * padding);

                g.setFont(new Font(Font.SERIF, Font.BOLD, 40));
                FontMetrics fm = g.getFontMetrics();
                int stringWidth = fm.stringWidth("i");
                int stringHeight = 27; // magic
                g.drawString("i", (userWidth - (float) stringWidth) / 2,
                                  (userHeight + (float) stringHeight) / 2);

                g.dispose();
                return variant;
            });
            return new ImageIcon(mrImage);
        }

        static <T extends Icon> T avoidMrLeak(T icon) {
            if (icon instanceof ImageIcon) {
                ((ImageIcon) icon).setImageObserver(DummyObserver.INSTANCE);
            }
            return icon;
        }

    }


    static class LeakedComponent extends JLabel {
        LeakedComponent(Icon icon) {
            super(icon);
        }
    }


}

            // Using Java-internal class just for test/demo purpose.
            Image mrImage = new sun.awt.image.MultiResolutionCachedImage(userWidth, userHeight,

Use --add-opens java.desktop/sun.awt.image=ALL-UNNAMED JVM option to prevent:

Exception in thread "AWT-EventQueue-0" java.lang.IllegalAccessError: class net.example.swing.MrImageObserverLeakTest$TestIcon (in unnamed module @0x130fefce) cannot access class sun.awt.image.MultiResolutionCachedImage (in module java.desktop) because module java.desktop does not export sun.awt.image to unnamed module @0x130fefce
	at net.example.swing.MrImageObserverLeakTest$TestIcon.createMrIcon(MrImageObserverLeakTest.java:287)
	at net.example.swing.MrImageObserverLeakTest$TabContent.<init>(MrImageObserverLeakTest.java:232)
	at net.example.swing.MrImageObserverLeakTest$1.actionPerformed(MrImageObserverLeakTest.java:70)