PopulationGraphGUI throws unexpected exception

[slemonide]

At completely random times, PopulationGraphGUI throws the following error:

Exception in thread "JavaFX Application Thread" java.util.ConcurrentModificationException
	at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:901)
	at java.util.ArrayList$Itr.next(ArrayList.java:851)
	at java.util.Collections$UnmodifiableCollection$1.next(Collections.java:1042)
	at javafx.scene.chart.LineChart.layoutPlotChildren(LineChart.java:468)
	at javafx.scene.chart.XYChart.layoutChartChildren(XYChart.java:731)
	at javafx.scene.chart.Chart$1.layoutChildren(Chart.java:94)
	at javafx.scene.Parent.layout(Parent.java:1087)
	at javafx.scene.Parent.layout(Parent.java:1093)
	at javafx.scene.Parent.layout(Parent.java:1093)
	at javafx.scene.Scene.doLayoutPass(Scene.java:552)
	at javafx.scene.Scene$ScenePulseListener.pulse(Scene.java:2397)
	at com.sun.javafx.tk.Toolkit.lambda$runPulse$30(Toolkit.java:355)
	at java.security.AccessController.doPrivileged(Native Method)
	at com.sun.javafx.tk.Toolkit.runPulse(Toolkit.java:354)
	at com.sun.javafx.tk.Toolkit.firePulse(Toolkit.java:381)
	at com.sun.javafx.tk.quantum.QuantumToolkit.pulse(QuantumToolkit.java:510)
	at com.sun.javafx.tk.quantum.QuantumToolkit.pulse(QuantumToolkit.java:490)
	at com.sun.javafx.tk.quantum.QuantumToolkit.lambda$runToolkit$404(QuantumToolkit.java:319)
	at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
	at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
	at com.sun.glass.ui.win.WinApplication.lambda$null$148(WinApplication.java:191)
	at java.lang.Thread.run(Thread.java:745)

It could be related to update() method updating the dataSeries.getData() outside the JavaFX start() method.

[jsondoo]

In PopulationGraphGUI.java, I'm trying to remove the unchecked call warning.

public void update(Observable o, Object arg) {
        if (arg.equals("tick")) {
                XYChart.Data<Integer,Integer> xydata = new XYChart.Data<>(WorldManager.getInstance().getGeneration(),
                        WorldManager.getInstance().getCells().size());
                dataSeries.getData().add(xydata);
                if (dataSeries.getData().size() > MAX_GENERATIONS) {
                    dataSeries.getData().remove(0);
                }
        }
    }

Unchecked call to 'add(E)' as a member of raw type 'java.util.List' when you try to add xydata
I doubt that will resolve the issue but it might be related

[slemonide]

I was implementing another class that uses WorldManager.getInstance().getCells() which was iterating over it and which was quite slow each iteration.

What I figured out is that due to the fact that WorldManager runs in a separate thread, world is modified while the function iterates over all cells. This is the cause of the problem.

[slemonide]

Now just need to figure out how to work with the same Collection from different threads.

[slemonide]

Apparently, iterator() is no help since elements are being added during the iteration by the tick() method.
Would it be reasonable to stop the thread while iterating?

[jsondoo]

Oh nice. That sounds reasonable to me, you will just have to ensure that only one thread is accessing Collection using thread states. Ill give it a try later

[jsondoo]

Also maybe using javafx.concurrent might help? http://docs.oracle.com/javafx/2/threads/jfxpub-threads.htm

[slemonide]

Good idea. Also, I am thinking about redesigning the system so that Observers can read just the differences, not the whole data.

[slemonide]

Apparently, deleting any relation between the database and the GUI doesn't solve the problem.

Probably, problem is partially due to the JavaFX.

[slemonide]

This might be helpful: http://stackoverflow.com/questions/22089022/line-chart-live-update

[slemonide]

Problem solved!