7189299 DefaultButtonModel instance keeps stale listeners of JButton in case of multiple SwingUtilities.updateComponentTreeUI() calls (original) (raw)

Frank Ding dingxmin at linux.vnet.ibm.com
Thu Dec 6 08:39:43 UTC 2012

Hi Alexandr, I did several attempts but still have hang issues somewhere. It seems the new approach of caching gui components created each time is not practical because of the threading restriction already imposed on HTMLDocument. Can we make compromise by turning to previous solution (v7 in particular) and generalize it to other gui components (which means there would be JCheckBoxWrapper, JRadioButtonWrapper, JPasswordFieldWrapper, JTextFieldWrapper, JListWrapper, JComboBoxWrapper, and JButtonWrapper).
Or shall we fix JButton only because it causes obvious exception visible to client? I am short of ideas... http://cr.openjdk.java.net/~dingxmin/7189299/webrev.07/

Best regards, Frank

On 12/5/2012 2:12 PM, Frank Ding wrote:

Hi Alexandr, I observed the same issue in my environment as well. My proposed patch would cause severe regression issues. I am looking into the locking issue.

Thanks, Frank On 12/3/2012 6:53 PM, Alexander Scherbatiy wrote:

Could you check the following sample with your latest fix? It just hangs on my side. - put the sample.html and the response.html files on a server - update path to the html files in the LoadingWebPageToJEditorPane class ------------- sample.html ------------ Username: ------------- response.html ------------ Hello World! ------------- LoadingWebPageToJEditorPane.html ------------ import java.net.URL; import javax.swing.JEditorPane; import javax.swing.JFrame; import javax.swing.JScrollPane; import javax.swing.SwingUtilities; public class LoadingWebPageToJEditorPane { private static final String HTMLPATH = "http://serever/path/sample.html"; public static void main(String[] a) throws Exception { SwingUtilities.invokeAndWait(new Runnable() { @Override public void run() { try { JFrame frame = new JFrame(); frame.setDefaultCloseOperation(JFrame.EXITONCLOSE); JEditorPane editorPane = new JEditorPane(); editorPane.setPage(new URL(HTMLPATH)); frame.add(new JScrollPane(editorPane)); frame.setSize(300, 200); frame.setVisible(true); SwingUtilities.updateComponentTreeUI(editorPane); } catch (Exception ex) { throw new RuntimeException(ex); } } }); } } --------------------------------------- Thanks, Alexandr. On 11/28/2012 10:29 AM, Frank Ding wrote: Hi Alexandr, I created a new patch v8 @ http://cr.openjdk.java.net/~dingxmin/7189299/webrev.08/. It uses the newly proposed approach mentioned in my last email. Could you please help to review it again? The patch, of course, passed jtreg test bug7189299.java in the patch. What's more, I did additional tests for JComboBox, JTextField and JList in my IDE by comparing listener numbers observed during debugging with/without my patch. The listener numbers were doubled without the fix. This proves that v8 patch works for all components. I think I can write those additional tests as jtreg tests after the patch passes review. One notable change is that I had to restrict the scope of holding a write lock in DefaultStyledDocument because otherwise, we cannot store the new component created in FormView.createComponent(). The stack trace is pasted below for reference. Exception in thread "main" java.lang.reflect.InvocationTargetException at java.awt.EventQueue.invokeAndWait(EventQueue.java:1270) at javax.swing.SwingUtilities.invokeAndWait(SwingUtilities.java:1350) at bug7189299.main(bug7189299.java:116) Caused by: java.lang.IllegalStateException: Attempt to mutate in notification at javax.swing.text.AbstractDocument.writeLock(AbstractDocument.java:1357) at javax.swing.text.html.HTMLDocument.obtainLock(HTMLDocument.java:1708) at javax.swing.text.html.FormView.createComponent(FormView.java:211) ......(omitted)...... at javax.swing.plaf.basic.BasicTextUI$RootView.insertUpdate(BasicTextUI.java:1602) at javax.swing.plaf.basic.BasicTextUI$UpdateHandler.insertUpdate(BasicTextUI.java:1861) at javax.swing.text.AbstractDocument.fireInsertUpdate(AbstractDocument.java:201) at javax.swing.text.DefaultStyledDocument.create(DefaultStyledDocument.java:155) <------ FormView.createComponent is triggered by this call which has already held the lock at javax.swing.text.html.HTMLDocument.create(HTMLDocument.java:469) ......(omitted)...... This change did violate what is documented in AbstractDocument.writeLock that "This situation violates the bean event model where order of delivery is not guaranteed and all listeners should be notified before further mutations are allowed. " However, without the change of shrinking lock scope, the component cannot be saved once it is created in FormView.createComponent(). I found it is even harder to save it later in code but perhaps there does exist a more appropriate place to do this. If you have any better suggestion, I am glad to know. Also I searched references to 'StyleConstants.ComponentAttribute' as you asked. The result is listed below. Note that the command 'grep' is invoked under openjdk 8 top directory. $ grep -R 'ComponentAttribute' . ./jdk/src/share/classes/javax/swing/text/StyleConstants.java: public static final Object ComponentAttribute = new CharacterConstants("component"); ./jdk/src/share/classes/javax/swing/text/StyleConstants.java: return (Component) a.getAttribute(ComponentAttribute); ./jdk/src/share/classes/javax/swing/text/StyleConstants.java: a.addAttribute(ComponentAttribute, c); ./jdk/src/share/classes/javax/swing/text/StyleConstants.java: Background, ComponentAttribute, IconAttribute, ./jdk/src/share/classes/javax/swing/text/StyledEditorKit.java: set.removeAttribute(StyleConstants.ComponentAttribute); Binary file ./jdk/test/sun/tools/jhat/jmap.bin matches So ComponentAttribute is not referenced by other classes except StyledEditorKit. StyleConstants exposes ComponentAttribute in getComponent() and setComponent() methods. References to StyleConstants.getComponent and StyleConstants.setComponent are further searched in repo. $ grep -R 'StyleConstants.getComponent' . ./jdk/src/share/classes/javax/swing/text/ComponentView.java: * the element (by calling StyleConstants.getComponent). A ./jdk/src/share/classes/javax/swing/text/ComponentView.java: Component comp = StyleConstants.getComponent(attr); $ grep -R 'StyleConstants.setComponent' . ./jdk/src/share/classes/javax/swing/JTextPane.java: StyleConstants.setComponent(inputAttributes, c); From the facts above, I think we are sufficiently confident to use ComponentAttribute. Please let me know if you have any comments and I can do more regression tests and provide more jtreg test cases as next step. Thanks and regards, Frank On 11/15/2012 5:18 PM, Alexander Scherbatiy wrote: On 11/14/2012 10:22 AM, Frank Ding wrote: Hi Alexandr, After a couple of hours investigating the possibility of fixing JComboBox.setModel(null) and JTextComponent.setComponent(null), I found that 1. In JComboBox.setModel, the new model, null in this case, is eventually passed to BasicComboPopup.propertyChange where JList.setModel is called. JList.setModel rejects the null model because of its api restriction. Below I listed the offending call stacks in my IDE. This makes sense as the associated drop down JList needs new model. However, it makes fixing JComboBox.setModel(null) hard or impossible. Exception in thread "main" java.lang.IllegalArgumentException: model must be non null at javax.swing.JList.setModel(JList.java:1674) at javax.swing.plaf.basic.BasicComboPopup$Handler.propertyChange(BasicComboPopup.java:939) at java.beans.PropertyChangeSupport.fire(PropertyChangeSupport.java:335) at java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:327) at java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:263) at java.awt.Component.firePropertyChange(Component.java:8413) at javax.swing.JComboBox.setModel(JComboBox.java:322)

2. JTextComponent.setComponent(null) can be fixed but code change in BasicTextUI is also required. Since setting null model to JComboBox, JList and JTextComponent is impossible or dangerous, just as you mentioned, we could set a non null new model to these UI components just for the purpose of having the side effect of removing listeners from old model. Are you ok with this approach? Yes. Please, try this and run the html swing automated tests from the test/javax/swing/text/html diroctory to check possible regressions. Thanks, Alexandr. By the way, I will investigate your another question "Could you also check that the StyleConstants.ComponentAttribute property value can't be rewritten by the JDK code or by public methods." and reply soon. Best regards, Frank On 11/13/2012 7:49 PM, Alexander Scherbatiy wrote: On 11/13/2012 11:53 AM, Frank Ding wrote: Hi Alexandr, As for your comment "Could you create an issue that a JComboBox.setModel(null) call throws NPE? You could fix it before the 7189299 issue. ", I created a bug with internal review ID of 2381499 on JComboBox.setModel(null). But test shows that JPasswordField.setDocument(null), JTextField.setDocument(null), JList.setModel(null) and JTextArea.setDocument(null) all throw NPE. Particularly, JList.setModel(null) has null check and throws IllegalArgumentException("model" must be non null"). Shall I include those components as well?

There is the javadoc for the JList setModel() method: Throws IllegalArgumentException - if model is null. So it is undesirable to change the public API. However, it is possible to set a new empty model for the JList. The list listeners should be removed from the old model in this case. You could have only 2 issues: one for components that allow to set a null model but throws NPE (like JComboBox) and another for components that does not allow to set null model but they do not remove listeners from the old model in case if a new model is set. Thanks, Alexandr.

Thanks for your guidance in advance.

Best regards, Frank On 11/8/2012 10:55 PM, Alexander Scherbatiy wrote: On 11/7/2012 10:56 AM, Frank Ding wrote: Hi Alexandr, Unfortunately, all the JComponents involved in FormView.createComponent() have bugs! I have done tests for all other swing components, i.e. JCheckBox, JRadioButton, JPasswordField, JTextField, JList, JComboBox and JTextField. Sadder news is that if we fix all components in the same way as I did for JButton, we need to subclass them all, resulting in JCheckBoxWrapper, JRadioButtonWrapper, JPasswordFieldWrapper, JTextFieldWrapper, JListWrapper, JComboBoxWrapper, JTextFieldWrapper plus JButtonWrapper! This approach becomes unacceptable when all swing components are affected. Shall we fix it in other way illustrated below? 1. Whenever a swing component is created, it is kept in AttributeSet, as what is now for model. 2. In FormView.createComponent(), the old swing component can be retrieved via attr.getAttribute(StyleConstants.ComponentAttribute). Note that ComponentAttribute is newly added. This way should be carefully investigated that it does not introduce new memory leaks. Could you also check that the StyleConstants.ComponentAttribute property value can't be rewritten by the JDK code or by public methods.

3. Before setting shared model to a newly initialized swing component, call oldComp.setModel(null), delegating deregistration to setModel method. 4. Seems some setModel such as AbstractButton.setModel() can function well when the param, new model, is null while JComboBox.setModel() will throw NPE in case of null param. Could you create an issue that a JComboBox.setModel(null) call throws NPE? You could fix it before the 7189299 issue. Thanks, Alexandr. 5. Add null check code in those problematic setModel or setDocument methods.

Any idea is appreciated. Thanks. Best regards, Frank On 11/6/2012 9:26 PM, Alexander Scherbatiy wrote: On 11/5/2012 11:20 AM, Frank Ding wrote: Hi Alexander, Based on your comments last time, I refined my patch of v6 and offered v7 @ http://cr.openjdk.java.net/~dingxmin/7189299/webrev.07/

This version of the fix looks good for me. It seems that it is the only good way to check that a button model contains AbstarctButton.Handler listener. Could you also check that others models used in the createComponent() method do not have such memory leaks (even the NPE is not thrown)?

4. Could you add the check that the action listener is invoked only once after a component tree updating and the action does the same that it does before a component tree updating? Answer: I am afraid I could not make it in the auto test (bug7189299.java) but I can achieve it to some degree in manual test FormSubmit, the one you illustrated below. My idea of checking it in FormSubmit.java is subclassing JEditorPane and overriding 'public EditorKit getEditorKit()' where stack traces can be examined in the overridden method to make sure FormView.submitData occurs only once. This approach works because FormView.submitData() calls JEditorPane.getEditorKit but is tricky. However, it's the only way I can think of without any additional framework support. If you are in favor of adding the check in FormSubmit.java, I am willing to do that. At least a separated manual test can be added that asks a user to put a response.html file to a server and according to the server url checks that JTeditor pane show the response text after a button pressing. html = new JEditorPane("text/html", "<form action="" + userURL + "">" + "<input type=submit name=submit_ _value="submit"/>" + ""); response.html: Hello World! Thanks, Alexandr. Thanks again for all your comments and your support. Once again, if you have any further concern or comment, please don't hesitate to let me know.

Best regards, Frank

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