JDK-6758673 : WeakReference leak in Window.ownedWindowList
  • Type: Bug
  • Component: client-libs
  • Sub-Component: java.awt
  • Affected Version: 7
  • Priority: P2
  • Status: Closed
  • Resolution: Fixed
  • OS: generic
  • CPU: generic
  • Submitted: 2008-10-13
  • Updated: 2013-06-22
  • Resolved: 2011-03-07
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JDK 6 JDK 7
6u60Fixed 7 b48Fixed
Description
There is a leak in the list of owned child windows for every window. Run the attached test and check output: test prints two counters, one for weak reference with null value, and another is for not-null value. It's clear that target objects (child windows) are properly destroyed, however the corresponding weak refereces are never removed from ownedWindowList.
Comments
SUGGESTED FIX --- a/src/share/classes/java/awt/Window.java Mon Sep 29 20:16:42 2008 +0200 +++ b/src/share/classes/java/awt/Window.java Mon Oct 13 13:26:49 2008 +0400 @@ -53,6 +53,7 @@ import sun.awt.CausedFocusEvent; import sun.awt.CausedFocusEvent; import sun.awt.SunToolkit; import sun.awt.util.IdentityArrayList; +import sun.java2d.Disposer; import sun.java2d.pipe.Region; import sun.security.action.GetPropertyAction; import sun.security.util.SecurityConstants; @@ -409,8 +410,6 @@ public class Window extends Container im } modalExclusionType = Dialog.ModalExclusionType.NO_EXCLUDE; - - sun.java2d.Disposer.addRecord(anchor, new WindowDisposerRecord(appContext, this)); } /** @@ -540,6 +539,8 @@ public class Window extends Container im if (owner != null) { owner.addOwnedWindow(weakThis); } + + Disposer.addRecord(anchor, new WindowDisposerRecord(appContext, this)); } /**
13-10-2008
EVALUATION The problem is easily understandable. Indeed, when a window disposer record is created: WindowDisposerRecord(AppContext context, Window victim) { owner = new WeakReference<Window>(victim.getOwner()); weakThis = victim.weakThis; this.context = new WeakReference<AppContext>(context); } victim's owner is still null, because WindowDisposerRecord is called from init(), while owner is instantiated in ownedInit(). That's why I suggest moving window disposer record creation into the end of ownedInit() - see suggested fix for details.
13-10-2008