Updating JavaFX BarChart data causes memory leak?

[Adam Granger]

Hi, I've just asked this on stackoverflow, but I'm guessing someone from
this group might be able to help better... Should I raise a JIRA?

I've discovered what I believe is a memory leak in BarChart triggered by
replacing all the data values in the series. This is exasperated by our
application which does this several times a second.

Using `jvisualvm` shows an uncontrolled growth in the number of
javafx.scene.layout.StackPane instances which eventually results in an
OutOfMemoryError. Styled StackPane nodes are used internally by BarChart
for the bars.

I've tried a different strategies to update the list. All exhibit the same
issue.

    // 1
    series.getData().clear();
    series.getData().addAll(list);
    // 2
    series.getData().setAll(list);
    // 3
    series.setData(list)

Interestingly the example in the BarChart tutorial updates values by
adding all the points first, and then mutating using
XYChart.Data.setYValue(). This could work, but is not convenient for us as
the number of data points can vary dynamically.

Specific questions

 * Is there anyway to avoid this issue, other than a extra logic using the
setYValue() approach above.
 * Have I stumbled across an actual memory leak in JavaFX? or just an
artefact of my misuse of the API? Surely freeing internal nodes when data
is updated is JavaFX responsibility

Example

    public class ChartUpdate extends Application {
        private int clock;
        public static void main(String[] args) {
            launch(args);
        }
        @Override
        public void start(Stage stage) {
            CategoryAxis xAxis = new CategoryAxis();
            NumberAxis yAxis = new NumberAxis(0, 100, 10);
            yAxis.setAutoRanging(false);
            BarChart<String, Number> graph = new BarChart<>(xAxis, yAxis);
            graph.setAnimated(false);
            Series<String, Number> series = new Series<>();
            graph.getData().add(series);
            stage.setScene(new Scene(graph));
            stage.show();

            Timeline timeLine = new Timeline();
            timeLine.getKeyFrames().add(
                    new KeyFrame(Duration.millis(500),
                            (e) -> {
                                ObservableList<Data<String, Number>> list
= FXCollections.observableArrayList();
                                for (int i = 0; i < 100; i++) {
                                    list.add(new Data<>(String.valueOf(i),
(clock + i) % 100));
                                }
                                series.setData(list);
                                clock++;
                            }));
            timeLine.setCycleCount(Animation.INDEFINITE);
            timeLine.play();
        }
    }