[BUG] Memory Leak when appending single character to StyleClassedTextArea

[asafl1976]

Hi,
I have a strange problem..
When printing a single character to StyleClassedTextArea every 50ms, memory usage keeps growing
until application is very slow and not responding. In the examples below, I'm using a thread to update the textarea but in my real application the character comes from serial port at the same rate (50ms).
This bug does not happen if using richtextfx-fat-0.8.2.jar, only when using richtextfx-fat-0.9.0.jar and up.

Whats strange about it is that when printing more than just a single character at one time, for example - "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\n" or when printing single character with new-line "a\n" than there is no memory leak and everything seems to be OK.

See the code "Memory leak" for the example where there is a memory leak.
See the commented code "NO Memory leak 1" and "NO Memory leak 2" for examples where there is no memory leak.

Any help/suggestions how to solve this will be highly appreciated :)
THANKS

import javafx.application.Application;
import javafx.application.Platform;
import javafx.beans.value.ObservableBooleanValue;
import javafx.scene.Scene;
import javafx.scene.layout.AnchorPane;
import javafx.stage.Stage;
import org.fxmisc.flowless.VirtualizedScrollPane;
import org.fxmisc.richtext.StyleClassedTextArea;
import org.fxmisc.undo.UndoManager;
import org.reactfx.value.Val;

import java.util.concurrent.atomic.AtomicBoolean;

public class Main extends Application {
    private Thread memoryMonitorThread;
    private AtomicBoolean runMemoryMonitorThread = new AtomicBoolean(true);
    private AtomicBoolean runCharPrintThread = new AtomicBoolean(true);

    @Override
    public void start(Stage primaryStage) throws Exception{
        AnchorPane root = new AnchorPane();
        StyleClassedTextArea textArea = new StyleClassedTextArea();
        VirtualizedScrollPane scrollPane = new VirtualizedScrollPane<>(textArea);
        textArea.setUndoManager(getNoOpUndoManager());

        AnchorPane.setBottomAnchor(scrollPane, 0.0);
        AnchorPane.setTopAnchor(scrollPane, 0.0);
        AnchorPane.setLeftAnchor(scrollPane, 0.0);
        AnchorPane.setRightAnchor(scrollPane, 0.0);
        root.getChildren().add(scrollPane);

        primaryStage.setTitle("Memory Leak");
        primaryStage.setScene(new Scene(root, 800, 400));
        primaryStage.show();

        new Thread(()-> {
            while(runCharPrintThread.get()) {
                sleep(50);
                Platform.runLater(() -> {
                    textArea.appendText("a");
                });
                sleep(50);
                Platform.runLater(() -> {
                    textArea.deleteText(textArea.getLength() - 1, textArea.getLength());
                });
            }
        }).start();

//        ////////////////////// NO Memory leak 2 /////////////////////////
//        new Thread(()-> {
//            while(runCharPrintThread.get()) {
//                try {
//                    Thread.sleep(50);
//                } catch (InterruptedException e) {
//                }
//                Platform.runLater(() -> {
//                    textArea.appendText("a\n");
//                    scrollPane.scrollYBy(Double.MAX_VALUE);
//                });
//            }
//        }).start();
//        ////////////////////////////////////////////////////////////

        startMemoryUsageMonitorThread();
        primaryStage.setOnCloseRequest(t -> {
            runMemoryMonitorThread.set(false);
            memoryMonitorThread.interrupt();
            runCharPrintThread.set(false);
        });
    }
    private void sleep(long mills) {
        try {
            Thread.sleep(mills);
        } catch (InterruptedException e) {
        }
    }

    private void startMemoryUsageMonitorThread() {
        memoryMonitorThread = new Thread(()-> {
            while(runMemoryMonitorThread.get()) {
                long memory = (Runtime.getRuntime().totalMemory() - Runtime.getRuntime().freeMemory()) / (1024 * 1024);
                System.out.println("Used Memory: " + memory + "MB");
                try {  Thread.sleep(10000);
                } catch (InterruptedException e) {
                }
            }
        });
        memoryMonitorThread.start();
    }

    private UndoManager getNoOpUndoManager() {
        return new UndoManager() {
            private final Val<Boolean> alwaysFalse = Val.constant(false);
            @Override public boolean undo() { return false; }
            @Override public boolean redo() { return false; }
            @Override public Val<Boolean> undoAvailableProperty() { return alwaysFalse; }
            @Override public boolean isUndoAvailable() { return false; }
            @Override public Val<Boolean> redoAvailableProperty() { return alwaysFalse; }
            @Override public boolean isRedoAvailable() { return false; }
            @Override public boolean isPerformingAction() { return false; }
            @Override public boolean isAtMarkedPosition() { return false; }
            // not sure whether these may throw NPEs at some point
            @Override public Val nextUndoProperty() { return null; }
            @Override public Val nextRedoProperty() { return null; }
            @Override public ObservableBooleanValue performingActionProperty() { return null; }
            @Override public UndoPosition getCurrentPosition() { return null; }
            @Override public ObservableBooleanValue atMarkedPositionProperty() { return null; }
            // ignore these
            @Override public void preventMerge() { }
            @Override public void forgetHistory() { }
            @Override public void close() { }
        };
    }


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

[Jugen]

Thanks @asafl1976 this has been addressed via #779

[asafl1976]

Thanks @Jugen, is there anything I can do in my code to overcome this problem or should I wait for a fix in next version?
Thanks

[Jugen]

@asafl1976 I don't think there is anything you can do in your code, so you'll need to wait for the next version which I plan on releasing by the end of next week.

[asafl1976]

Thanks!!