memorymonitor.java

MemoryMonitor demonstrates the use of the java.lang.management API in observing the memory usage o

            int graphX = x1+30;
            int graphY = y1 + (int) ssH;
            int graphW = (int) remainingWidth;
            int graphH = (int) remainingHeight;

            graphOutlineRect.setRect(graphX, graphY, graphW, graphH);
            big.draw(graphOutlineRect);

            int graphRow = graphH/10;

            // .. Draw row ..
            for (int j = graphY; j <= graphH+graphY; j += graphRow) {
                graphLine.setLine(graphX,j,graphX+graphW,j);
                big.draw(graphLine);
            }
        
            // .. Draw animated column movement ..
            int graphColumn = graphW/15;

            if (columnInc == 0) {
                columnInc = graphColumn;
            }

            for (int j = graphX+columnInc; j < graphW+graphX; j+=graphColumn) {
                graphLine.setLine(j,graphY,j,graphY+graphH);
                big.draw(graphLine);
            }

            --columnInc;

            // Plot memory usage by this memory pool.	
            if (usedMem[npool] == null) {
		usedMem[npool] = new float[usageHistCount];
                ptNum[npool] = 0;
            } 

	    // save memory usage history.
	    usedMem[npool][ptNum[npool]] = usedMemory;

            big.setColor(Color.yellow);

	    int w1; // width of memory usage history.
	    if (ptNum[npool] > graphW) {
	        w1 = graphW;
	    } else {
		w1 = ptNum[npool]; 
            }


            for (int j=graphX+graphW-w1, k=ptNum[npool]-w1; k < ptNum[npool]; 
								k++, j++) {
                 if (k != 0) {
                     if (usedMem[npool][k] != usedMem[npool][k-1]) {
		         int h1 = (int)(graphY + graphH * ((totalMemory -usedMem[npool][k-1])/totalMemory));
		         int h2 = (int)(graphY + graphH * ((totalMemory -usedMem[npool][k])/totalMemory));
                         big.drawLine(j-1, h1, j, h2);
                     } else {
		         int h1 = (int)(graphY + graphH * ((totalMemory -usedMem[npool][k])/totalMemory));
                         big.fillRect(j, h1, 1, 1);
                     }
                 }
            }
            if (ptNum[npool]+2 == usedMem[npool].length) {
                // throw out oldest point
                for (int j = 1;j < ptNum[npool]; j++) {
                     usedMem[npool][j-1] = usedMem[npool][j];
                }
                --ptNum[npool];
            } else {
                ptNum[npool]++;
            }
        }


        public void start() {
            thread = new Thread(this);
            thread.setPriority(Thread.MIN_PRIORITY);
            thread.setName("MemoryMonitor");
            thread.start();
        }


        public synchronized void stop() {
            thread = null;
            notify();
        }

        public void run() {

            Thread me = Thread.currentThread();

            while (thread == me && !isShowing() || getSize().width == 0) {
                try {
                    thread.sleep(500);
                } catch (InterruptedException e) { return; }
            }
	
            while (thread == me && isShowing()) {
                Dimension d = getSize();
                if (d.width != w || d.height != h) {
                    w = d.width;
                    h = d.height;
                    bimg = (BufferedImage) createImage(w, h);
                    big = bimg.createGraphics();
                    big.setFont(font);
                    FontMetrics fm = big.getFontMetrics(font);
                    ascent = (int) fm.getAscent();
                    descent = (int) fm.getDescent();
                }
                repaint();
                try {
                    thread.sleep(sleepAmount);
                } catch (InterruptedException e) { break; }
                if (MemoryMonitor.dateStampCB.isSelected()) {
                     System.out.println(new Date().toString() + " " + usedStr);
                }
            }
            thread = null;
        }
    }


    // Test thread to consume memory
    static class Memeater extends ClassLoader implements Runnable {
	Object y[];
	public Memeater() {}
	public void run() {
	    y = new Object[10000000];
	    int k =0;
	    while(true) {
	         if (k == 5000000) k=0;
	         y[k++] = new Object();
	         try {
		     Thread.sleep(20);
	         } catch (Exception x){}

		 // to consume perm gen storage
	         try {
                     // the classes are small so we load 10 at a time
                     for (int i=0; i<10; i++) {
                        loadNext();
                     }
                 } catch (ClassNotFoundException x) {
		   // ignore exception
                 }

	   }

	}

	Class loadNext() throws ClassNotFoundException {

            // public class TestNNNNNN extends java.lang.Object{
            // public TestNNNNNN();
            //   Code:
            //    0:    aload_0
            //    1:    invokespecial   #1; //Method java/lang/Object."<init>":()V
            //    4:    return
            // }

            int begin[] = {
                0xca, 0xfe, 0xba, 0xbe, 0x00, 0x00, 0x00, 0x30,
                0x00, 0x0a, 0x0a, 0x00, 0x03, 0x00, 0x07, 0x07,
                0x00, 0x08, 0x07, 0x00, 0x09, 0x01, 0x00, 0x06,
                0x3c, 0x69, 0x6e, 0x69, 0x74, 0x3e, 0x01, 0x00,
                0x03, 0x28, 0x29, 0x56, 0x01, 0x00, 0x04, 0x43,
                0x6f, 0x64, 0x65, 0x0c, 0x00, 0x04, 0x00, 0x05,
                0x01, 0x00, 0x0a, 0x54, 0x65, 0x73, 0x74 };

            int end [] = {
                0x01, 0x00, 0x10,
                0x6a, 0x61, 0x76, 0x61, 0x2f, 0x6c, 0x61, 0x6e,
                0x67, 0x2f, 0x4f, 0x62, 0x6a, 0x65, 0x63, 0x74,
                0x00, 0x21, 0x00, 0x02, 0x00, 0x03, 0x00, 0x00,
                0x00, 0x00, 0x00, 0x01, 0x00, 0x01, 0x00, 0x04,
                0x00, 0x05, 0x00, 0x01, 0x00, 0x06, 0x00, 0x00,
                0x00, 0x11, 0x00, 0x01, 0x00, 0x01, 0x00, 0x00,
                0x00, 0x05, 0x2a, 0xb7, 0x00, 0x01, 0xb1, 0x00,
                0x00, 0x00, 0x00, 0x00, 0x00 };


            // TestNNNNNN

            String name = "Test" + Integer.toString(count++);

            byte value[];
            try {
                value = name.substring(4).getBytes("UTF-8");
            } catch (java.io.UnsupportedEncodingException x) {
                throw new Error();
            }

            // construct class file

            int len = begin.length + value.length + end.length;
            byte b[] = new byte[len];
            int i, pos=0;
            for (i=0; i<begin.length; i++) {
                b[pos++] = (byte)begin[i];
            }
            for (i=0; i<value.length; i++) {
                b[pos++] = value[i];
            }
            for (i=0; i<end.length; i++) {
                b[pos++] = (byte)end[i];
            }

            return defineClass(name, b, 0, b.length);

	}
	static int count = 100000;
	
    }
	
    public static void main(String s[]) {
        final MemoryMonitor demo = new MemoryMonitor();
        WindowListener l = new WindowAdapter() {
            public void windowClosing(WindowEvent e) {System.exit(0);}
            public void windowDeiconified(WindowEvent e) { demo.surf.start(); }
            public void windowIconified(WindowEvent e) { demo.surf.stop(); }
        };
        JFrame f = new JFrame("MemoryMonitor");
        f.addWindowListener(l);
        f.getContentPane().add("Center", demo);
        f.pack();
        f.setSize(new Dimension(400,500));
        f.setVisible(true);
        demo.surf.start();
	Thread thr = new Thread(new Memeater());
	thr.start();
    }

}