FULL PRODUCT VERSION :
java version "1.8.0_60"
Java(TM) SE Runtime Environment (build 1.8.0_60-b27)
Java HotSpot(TM) 64-Bit Server VM (build 25.60-b23, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows [Version 6.1.7601]

A DESCRIPTION OF THE PROBLEM :
When child nodes are removed from a JavaFX parent, references to these nodes are held in a list ('removed'). This list is usually cleared when the scene graph is updated via Parent#impl_updatePeer.

If, however, you remove the parent from the scene graph (e.g. for emulating a card layout) the references will not be released. The 'removed' list is populated, but never cleared.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
The sample program attached below illustrates the issue. Run the application and attach to the running VM using jProfiler or a similar tool to verify that the allocated memory is indeed not freed.




EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Even though TestApp holds a reference to 'someParent', no reference to the BigComponent instance is being held in user code. The allocated memory should therefore be freed.
ACTUAL -
The application maintains a heap usage of 1GB that cannot be collected. Using jProfiler you can confirm that the only path to the GC root for the BigComponent instance is indeed Parent#removed

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
public class TestApp extends Application {
    private BorderPane someParent = new BorderPane(new BigComponent());

    @Override
    public void start(Stage stage) throws Exception {
        final Scene scene = new Scene(someParent);

        Platform.runLater(new Runnable() {
            @Override
            public void run() {
                scene.setRoot(new Label("Some other component"));
                someParent.setCenter(null);
            }
        });

        stage.setScene(scene);
        stage.show();
    }

    public static void main(String[] args) {
        Application.launch(TestApp.class, args);
    }

    private class BigComponent extends Pane {
        private double[] memoryHog = new double[1024*1024*128];
    }
}
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
None. The implementation in Parent would probably benefit from using WeakReferences for the 'removed' list.