Demonstration of a memory leak when relying on WeakInvalidationListener in cases when the value of ObservableValue it is attached to never changes. Two possible solutions are presented as well.

Leaky.java

import javafx.beans.property.SimpleDoubleProperty;

public class Leaky {

    public static void main(String[] args) throws InterruptedException {
        SimpleDoubleProperty a = new SimpleDoubleProperty(0.0);
        for(int i = 0; i < 1000000; ++i) {
            a.add(5).multiply(10).dispose();
        }
        reportMemoryUsage();
        a.add(0); // prevents a from being garbage collected until now
    }

    private static void reportMemoryUsage() {
        System.gc();
        Runtime runtime = Runtime.getRuntime();
        long used = runtime.totalMemory() - runtime.freeMemory();
        double mb = 1024*1024;
        System.out.printf("Used Memory after GC: %.2f MB", used / mb);
    }
}

NonLeaky.java

import javafx.beans.binding.DoubleBinding;
import javafx.beans.property.SimpleDoubleProperty;

public class NonLeaky {

    public static void main(String[] args) throws InterruptedException {
        SimpleDoubleProperty a = new SimpleDoubleProperty(0.0);
        for(int i = 0; i < 1000000; ++i) {
            DoubleBinding x = a.add(5);
            x.multiply(10);
            x.dispose(); // dispose the first binding in the chain
        }
        reportMemoryUsage();
        a.add(0); // prevents a from being garbage collected until now
    }

    private static void reportMemoryUsage() {
        System.gc();
        Runtime runtime = Runtime.getRuntime();
        long used = runtime.totalMemory() - runtime.freeMemory();
        double mb = 1024*1024;
        System.out.printf("Used Memory after GC: %.2f MB", used / mb);
    }
}

NonLeakyReactFX.java

import org.reactfx.value.Var;

public class NonLeakyReactFX {

    public static void main(String[] args) throws InterruptedException {
        Var<Double> a = Var.newSimpleVar(0.0);
        for(int i = 0; i < 1000000; ++i) {
            a.map(x -> (x + 5) * 10);
        }
        reportMemoryUsage();
        a.map(x -> x); // prevents a from being garbage collected until now
    }

    private static void reportMemoryUsage() {
        System.gc();
        Runtime runtime = Runtime.getRuntime();
        long used = runtime.totalMemory() - runtime.freeMemory();
        double mb = 1024*1024;
        System.out.printf("Used Memory after GC: %.2f MB", used / mb);
    }
}

output.md

Leaky.java:

Used Memory after GC: 52.73 MB

NonLeaky.java:

Used Memory after GC: 2.90 MB

NonLeakyReactFX.java:

Used Memory after GC: 0.98 MB

Discussion

The pure JavaFX NonLeaky solution breaks the fluency, because you have to store an intermediate binding in order to be able to dispose it later. The NonLeakyReactFX solution is fluent, but employs a third-party library ReactFX.