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RE: servlet and memory leakage

From: Laird, Brian <BLaird@perseco.com>
Date: Mon, 1 Dec 2003 09:28:12 -0600
Message-ID: <45A6279F82E4CA4BBDC0F4EFC7B6A2FE127F36@atlas.perseco.com>
To: "Red K" <redkresearch@yahoo.com.sg>, <www-jigsaw@w3.org>

Here are few of my comments / questions on this:

1) What version of the JDK are you using?
2) Can you upgrade to 2.2.3?
3) You need to be sure to do some clean up of all the IO classes.
Example, I didn't see a close or destroy for the BufferedImage or the
ImageWriter class.
4) You may need to start the JVM with more aggressive memory management.
Things like minimum & maximum heap size as well as the garbage
collection method.  

Hope this helps,
Brian

-----Original Message-----
From: Red K [mailto:redkresearch@yahoo.com.sg] 
Sent: Friday, November 28, 2003 2:28 AM
To: www-jigsaw@w3.org
Subject: servlet and memory leakage


Hi, dear all:

I wrote one servlet on Jigsaw 2.0.5. This servlet
draws one graph in memory and writes it the HTTP
response as an jpeg image.
I notice that every request to the servlet will cause
some amount of memory leakage in my Jigsaw server. And
if I request it at a higher rate, the Jigsaw server
will prompt it runs out of memory.
I just learn to use Java. However, I know that Java
claims automatic memory leakage prevension.
So I am puzzled. Is this problem caused by my poor
Java programming or by Jigsaw possible bugs?
The servlet is as the following:
--------------------------------
import java.io.*;
import java.util.*; 
import javax.servlet.ServletException; 
import java.io.*;
import java.util.*;
import javax.imageio.*;
import java.awt.image.*;
import java.awt.*;
import javax.imageio.stream.*;
import javax.servlet.ServletOutputStream; 
import javax.servlet.http.*;

public class StockImgServlet extends HttpServlet
{
        int[] A = new int[100];
        
        public void oneRead(String stock, int ratio)
throws IOException
        {
                //1. read in price list
                BufferedReader in = new
BufferedReader(new FileReader(stock));
                int i;
                for(i=0;i<100;i++)
                {
                        String line = in.readLine();
                        Integer value = new
Integer(line);
                        A[i] = value.intValue();
                }
                in.close();
        }
        
        public void doGet(HttpServletRequest req,
HttpServletResponse res)
        throws IOException, ServletException
        {
                //1. get stock and ratio values
                String stock =
req.getParameter("stock");
                String ratio_string =
req.getParameter("ratio");
                Integer ratio_obj = new
Integer(ratio_string);
                int ratio = ratio_obj.intValue();
                
                //2. set content type
                res.setContentType("image/jpeg");
               
res.setHeader("Cache-Control","no-cache");
                
                //3. check stock
                oneRead(stock,ratio);
                
                //4. generate img and dump out
                BufferedImage img = new
BufferedImage(500,250,BufferedImage.TYPE_BYTE_INDEXED);
                Graphics2D g = img.createGraphics();
                
                int i;
                for(i=0;i<100;i++)
                {
                        g.fillRect(i*5,A[i]*5,3,3);
                }
                for(i=1;i<100;i++)
                {
                       
g.drawLine((i-1)*5,A[i-1]*5,i*5,A[i]*5);
                }
                try
                {
                        Iterator w =
ImageIO.getImageWritersByMIMEType("image/jpeg");
                        ImageWriter writer =
(ImageWriter)w.next();
                        ImageOutputStream ios =
ImageIO.createImageOutputStream((OutputStream)(res.getOutputStream()));
                        writer.setOutput(ios);
                        writer.write(img);
                        ios.close();
                }
                catch(Exception e)
                {
                }               
        }
} 
--------------------------------

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Received on Monday, 1 December 2003 10:26:08 GMT

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