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servlet and memory leakage

From: Red K <redkresearch@yahoo.com.sg>
Date: Fri, 28 Nov 2003 16:27:57 +0800 (CST)
Message-ID: <20031128082757.47760.qmail@web14804.mail.yahoo.com>
To: www-jigsaw@w3.org

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 Friday, 28 November 2003 03:29:57 GMT

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