When canvas is removed from panel, there is still a
reference from the FocusManager of the frame to
the canvas. This memory leak from awt should be fixed.

Attach is a simple program to demonstration this.
This program extends canvas to display a
simply 2D rectangle.

  protected class TestCanvas extends Canvas
  {
    public TestCanvas(GraphicsConfiguration g) {
super(g);
    }

    public void paint(Graphics g) {
g.setColor(Color.blue);
g.fillRect(30, 30, 100, 100);
    }

    public void finalize() throws Throwable {
  super.finalize();
System.out.println("Canvas.finalize()");
    }
  }

When user close the Frame, the windowClosing listener
will remove canvas from the testPanel (which holds
testcanvas) and you should see the message
"TestPanel.finalize()"
print out from the testpanel finalize.

However "Canvas.finalize()" did not print out at all.
OptimizeIt shows that the reference is hold
by FocusManager of the window.


It is expected that the finalized method of Canvas invoked.


kelvin.chung@eng 2000-09-11
In the most recently version of Java3D, we try to
work around this problem by setting another FocusManager.
However there is still a reference from

target of
sun.awt.windows.WCanvasPeer.sn.awt.windows.WCanvasPeer

holding the reference which prevent Canvas3D from GC.