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Posted to commits@harmony.apache.org by "Alexei Zakharov (JIRA)" <ji...@apache.org> on 2007/10/15 16:52:50 UTC
[jira] Assigned: (HARMONY-4762) [classlib][swing][html] Flaw in
thread synchronization in BasicTextUI
[ https://issues.apache.org/jira/browse/HARMONY-4762?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Alexei Zakharov reassigned HARMONY-4762:
----------------------------------------
Assignee: Alexei Zakharov
> [classlib][swing][html] Flaw in thread synchronization in BasicTextUI
> ---------------------------------------------------------------------
>
> Key: HARMONY-4762
> URL: https://issues.apache.org/jira/browse/HARMONY-4762
> Project: Harmony
> Issue Type: Bug
> Components: Classlib
> Reporter: Vasily Zakharov
> Assignee: Alexei Zakharov
> Attachments: HARMONY-4762-BasicTextUI.patch
>
>
> javax.swing.plaf.basic.BasicTextUI has a synchronization mechanism implemented in readLock()/readUnlock() methods. These methods forward the calls to the corresponding methods of AbstractDocument class instance in document field.
> This mechanism has a flaw - sometimes the document field gets replaced by another thread between calls to readLock() and readUnlock(). This makes the readUnlock() call to fail.
> Here's the simple reproducer:
> import javax.swing.JEditorPane;
> import javax.swing.JFrame;
> public class Test {
> public static void main(String argv[]) {
> try {
> JFrame frame = new JFrame("Test");
> frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
> frame.setSize(100, 100);
> JEditorPane pane = new JEditorPane();
> frame.add(pane);
> frame.setVisible(true);
> pane.setPage("file:test.html");
> } catch (Throwable e) {
> e.printStackTrace(System.out);
> }
> }
> }
> test.html should exist in current directory and may be empty.
> This test produces the following exception on Harmony:
> java.lang.Error: This thread doesn't hold read lock.
> at javax.swing.text.AbstractDocument$ReadWriteLock.readUnlock(AbstractDocument.java:868)
> at javax.swing.text.AbstractDocument.readUnlock(AbstractDocument.java:1142)
> at javax.swing.plaf.basic.BasicTextUI.readUnlock(BasicTextUI.java:114)
> at javax.swing.plaf.basic.BasicTextUI.paintSafely(BasicTextUI.java:844)
> at javax.swing.plaf.basic.BasicTextUI.paint(BasicTextUI.java:88)
> at javax.swing.plaf.ComponentUI.update(ComponentUI.java:38)
> at javax.swing.plaf.basic.BasicTextUI.update(BasicTextUI.java:956)
> at javax.swing.JComponent.paintComponent(JComponent.java:897)
> at javax.swing.JComponent.paint(JComponent.java:994)
> at javax.swing.JComponent.paintDoubleBuffered(JComponent.java:1425)
> at javax.swing.JComponent.paintImmediately(JComponent.java:156)
> at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:186)
> at javax.swing.RepaintManager$1.run(RepaintManager.java:80)
> at java.awt.event.InvocationEvent.runAndNotify(InvocationEvent.java:98)
> at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:78)
> at java.awt.EventQueueCore.dispatchEventImpl(EventQueueCore.java:138)
> at java.awt.EventQueue.dispatchEvent(EventQueue.java:144)
> at java.awt.EventDispatchThread.runModalLoop(EventDispatchThread.java:74)
> at java.awt.EventDispatchThread.run(EventDispatchThread.java:48)
> The AbstractDocument instance mentioned on top of this stack is not the instance readLock() was called for.
> The error is intermittent and occurs not so often. To make it stable, one can add Thread.sleep(100) call to javax.swing.text.html.BlockView.paint() method as follows:
> public void paint(final Graphics g, final Shape allocation) {
> Rectangle rc = allocation.getBounds();
> try {
> Thread.sleep(100);
> } catch (InterruptedException e) {}
> boxPainter.paint(g, rc.x, rc.y, rc.width, rc.height, this);
> super.paint(g, allocation);
> }
> This change doesn't alter the code logic, but slows it down and makes the error to show off much more often.
> This issue was discovered while investigating HARMONY-4755.
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