Multithreading in JFreeChart

Question

I'm trying to monitor a group of computer resources online. In order to do that, i'm using JFreechart and try to use multithreading in order to gain performance.

Here is my code:

class osGenel extends JPanel implements Runnable {
    String name; 
    private static DefaultValueDataset[] DATASET;
    Integer VALUE,iii,sayac;
    Thread t;

    private static Sessionn[] obj;
    osGenel(String s,DefaultValueDataset valuedataset,Double n,Double w,Double c,int i) {
        name = s;
        iii=i;
        t = new Thread(this, name);
        this.setLayout(new GridLayout());
        DATASET[iii]=valuedataset;
        MeterPlot meterplot = new MeterPlot(DATASET[iii]);
        meterplot.setDialShape(DialShape.CIRCLE);
        meterplot.setRange(new Range(0.0D, 100D));
        meterplot.addInterval(new MeterInterval("Normal", new Range(0.0D, n), Color.lightGray, new BasicStroke(2.0F),Color.GREEN));
        meterplot.addInterval(new MeterInterval("Warning", new Range(n, w), Color.lightGray, new BasicStroke(2.0F), Color.YELLOW));
        meterplot.addInterval(new MeterInterval("Critical", new Range(w, c), Color.lightGray, new BasicStroke(2.0F), Color.RED));

        meterplot.setNeedlePaint(Color.darkGray);
        meterplot.setDialBackgroundPaint(Color.white);
        meterplot.setDialOutlinePaint(Color.gray);
        meterplot.setMeterAngle(260);
        meterplot.setTickLabelsVisible(true);
        meterplot.setTickLabelFont(new Font("Dialog", 1,25));
        meterplot.setTickLabelPaint(Color.darkGray);
        meterplot.setTickSize(5D);
        meterplot.setBackgroundPaint(Color.black);
        meterplot.setTickPaint(Color.lightGray);
        meterplot.setValuePaint(Color.black);
        meterplot.setValueFont(new Font("Dialog", 1, 0));

        JFreeChart chart = new JFreeChart(s, JFreeChart.DEFAULT_TITLE_FONT, meterplot, true);
        this.add(new ChartPanel(chart, false));
        t.start();
    }
    public void run() {
        try {

            for (int i = 100; i > 0; i--) {
                System.out.println(iii + ". Thread running");
                Random r=new Random();

                DATASET[iii].setValue(r.nextInt(100));
                Thread.sleep(3000);
            }
        } catch (InterruptedException e) {
            System.out.println(name + "Interrupted");
        }
        System.out.println(name + " Out.");
    }

    public static void main(String args[])
    {
        EventQueue.invokeLater(new Runnable() {

            @Override
            public void run() {
                DefaultValueDataset defaultvaluedataset = new DefaultValueDataset(23D);
                final JFrame f = new JFrame("OS MONITOR");
                f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
                obj=new Sessionn[9];
                DATASET=new DefaultValueDataset[9];
                f.setLayout(new GridLayout(3, 3));
                f.add(new osGenel("CPU", defaultvaluedataset,60D,90D,100D,0));
                f.add(new osGenel("DISK", defaultvaluedataset,60D,90D,100D,1));
                f.add(new osGenel("MEMORY", defaultvaluedataset,60D,90D,100D,2));
                f.add(new osGenel("CPU", defaultvaluedataset,60D,90D,100D,3));
                f.add(new osGenel("DISK", defaultvaluedataset,60D,90D,100D,4));
                f.add(new osGenel("MEMORY", defaultvaluedataset,60D,90D,100D,5));
                f.add(new osGenel("CPU", defaultvaluedataset,60D,90D,100D,6));
                f.add(new osGenel("DISK", defaultvaluedataset,60D,90D,100D,7));
                f.add(new osGenel("MEMORY", defaultvaluedataset,60D,90D,100D,8));
                f.pack();
                f.setVisible(true);
            }
        });
    }
}

The problem is, when i run this program, my threads are working, in each thread there is different value, but my datasets always get same value from these threads. I thought my each dataset will get different value, but it doesn't. All graphs show same value with each thread works.

Answer 1

You have one big problem, you use one instance of DefaultValueDataset for all your threads, in next code :

 DefaultValueDataset defaultvaluedataset = new DefaultValueDataset(23D);
 f.add(new osGenel("CPU", defaultvaluedataset,60D,90D,100D,0));
 f.add(new osGenel("DISK", defaultvaluedataset,60D,90D,100D,1));
 f.add(new osGenel("MEMORY", defaultvaluedataset,60D,90D,100D,2));
 f.add(new osGenel("CPU", defaultvaluedataset,60D,90D,100D,3));
 f.add(new osGenel("DISK", defaultvaluedataset,60D,90D,100D,4));
 f.add(new osGenel("MEMORY", defaultvaluedataset,60D,90D,100D,5));
 f.add(new osGenel("CPU", defaultvaluedataset,60D,90D,100D,6));
 f.add(new osGenel("DISK", defaultvaluedataset,60D,90D,100D,7));
 f.add(new osGenel("MEMORY", defaultvaluedataset,60D,90D,100D,8));

Because of that, you have the same result in each panel.

Change that code to:

f.add(new Test("CPU",  new DefaultValueDataset(23D), 60D, 90D, 100D, 0));
f.add(new Test("DISK",  new DefaultValueDataset(23D), 60D, 90D, 100D, 1));
f.add(new Test("MEMORY",  new DefaultValueDataset(23D), 60D, 90D, 100D, 2));
f.add(new Test("CPU",  new DefaultValueDataset(23D), 60D, 90D, 100D, 3));
f.add(new Test("DISK",  new DefaultValueDataset(23D), 60D, 90D, 100D, 4));
f.add(new Test("MEMORY",  new DefaultValueDataset(23D), 60D, 90D, 100D, 5));
f.add(new Test("CPU",  new DefaultValueDataset(23D), 60D, 90D, 100D, 6));
f.add(new Test("DISK",  new DefaultValueDataset(23D), 60D, 90D, 100D, 7));
f.add(new Test("MEMORY",  new DefaultValueDataset(23D), 60D, 90D, 100D, 8));

And you see expected result.