Optimizing memory leakage in JavaFX

Question

I have written a piece of code, to make letters appear and fly as I write them. The problem it consumes a lot of memory.

I already optimized it a little bit by

• Sharing the path object and update its parameters in listeners.
• Calling gc each time a new letter is printed

But it still uses a lot of memory, so any ideas about how to reduce its memory utilization ?

Thanks in advance.

    package sample;

    import javafx.animation.PathTransition;
    import javafx.application.Application;
    import javafx.scene.Scene;
    import javafx.scene.layout.Pane;
    import javafx.scene.paint.Color;
    import javafx.scene.shape.LineTo;
    import javafx.scene.shape.MoveTo;
    import javafx.scene.shape.Path;
    import javafx.scene.text.Font;
    import javafx.scene.text.Text;
    import javafx.stage.Stage;
    import javafx.util.Duration;

    public class Main extends Application {

        public static void main(String[] args) {
            launch(args);
        }

        @Override
        public void start(Stage primaryStage) throws Exception {
            Pane root = new Pane();
            Scene scene = new Scene(root);
            root.setCache(false);
            primaryStage.setTitle("Hello World");
            primaryStage.setScene(scene);


            Path path = new Path();
            root.widthProperty().addListener((observableValue, oldSceneWidth, newSceneWidth) -> SetPathElements(path, root));
            root.heightProperty().addListener((observableValue, oldSceneWidth, newSceneWidth) -> SetPathElements(path, root));


            Duration duration = Duration.millis(1000);

            scene.setOnKeyPressed(event -> {
                System.gc();

                Text textNode = new Text(event.getText());
                textNode.setFont(Font.font(50));
                textNode.setFill(Color.ORANGE);
                root.getChildren().add(textNode);


                PathTransition pathTransition = new PathTransition();
                pathTransition.setDuration(duration);
                pathTransition.setPath(path);
                pathTransition.setCycleCount(1);

                pathTransition.setNode(textNode);
                pathTransition.setOnFinished(event1 -> {
                    root.getChildren().remove(textNode);
                    pathTransition.setNode(null);
                    pathTransition.setPath(null);
                    textNode.setFont(null);
                    textNode.setFill(null);
                });
                pathTransition.play();


            });
            primaryStage.show();
        }

        private void SetPathElements(Path path, Pane root) {
            path.getElements().clear();
            double w = root.getWidth();
            double h = root.getHeight();
            path.getElements().add(new MoveTo(w / 2, h));
            path.getElements().add(new LineTo(w / 2, -40));
        }
    }

---

EDIT #1

OS: Arch Linux 64-bit Platform: Intel i7-3rd generation, 8 GB ram IDE : Intellij JDK : 1.8.0_102

Proof of leak : After typing around 100 chars it jumped from 50 MB to 1.3 GB

---

EDIT #2

I have checked Heap size using jvisualvm and it indicates that the Heap expands greatly but the used portion don't exceed ~50 MB

Answer 1

There is a memory leak in JavaFX with Mesa >=11.0 (meaning any up to date Linux distribution). JavaFX developers say it's a bug in Mesa, but I couldn't find a bug report in Mesa (nor could I file one, as I don't know how to reproduce it outside of JavaFX).
The only solutions as of now are -
1. Use an older Linux (the key is having Mesa 10 or lower)
2. Use an NVidia GPU - they have their own OpenGL implementation and don't rely on Mesa.
3. Use Windows.

Update (November 2016)
This issue seems to have been resolved in newer versions of Mesa and/or X.org. Updating to Mesa 13.0 and X.org >=1.18.4 should solve this issue.

Related links:

• openjfx-dev discussion thread.
• reddit discussion.
• Mesa discussion.
• Related SO post: JavaXF 8 ProgressBar and ProgressIndicator with process=-1 memory leak on Linux

Answer 2

The upgrade up to Mesa 13.0.4 does not fix the issue, but there is a workaround.

If the program is run with -Dprism.order=j2d or -Dprism.order=sw VM argument, JavaFX rendering engine does not use OpenGL, and the leak does not happen. Of course, the application performance is significantly degraded in this case.