Memory leak in Tomcat 5.5

Question

Hi all, i am experiencing memory leaks while using tomcat 5.5 and mysql connector 3.1.7.. While running the attached code tomcat swallows up to 20 mb and doesnt return it. I close down everything but the app still leaks mem. For now it's not an issue (Tomcat stays below 60mb mem of 1gb), however running this app on serveral clients will dramatically increase the memory allocation.
import java.sql.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.awt.Image;
import java.awt.Graphics2D;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import javax.swing.ImageIcon;
import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageEncoder;
public class Thumbs extends HttpServlet {
  private String dbDriver = "com.mysql.jdbc.Driver";
  private String dbURL = "jdbc:mysql://localhost/webapp?";
  private String userID = "javauser";
  private String passwd = "javadude";
  private Connection dbConnection;
  //Initialize global variables
  public void init() throws ServletException {
  //Process the HTTP Get request
  public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    try{
       String maxDim = "";
       String siteString = request.getParameterValues("s")[0];
       if (request.getParameterValues("d") != null){
           maxDim = request.getParameterValues("d")[0];
       if (maxDim == ""){
           response.setContentType("image/jpeg");
           OutputStream out = response.getOutputStream();
           writePicture(out,siteString);
       else{
           if (siteString != null) {
               int maxDimension = Integer.parseInt(maxDim);
               response.setContentType("image/jpeg");
               OutputStream out = response.getOutputStream();
               writeThumbnailPicture(out, siteString, maxDimension);
    } catch (Exception ex){
        ex.printStackTrace();
        log(ex.getMessage());
  public void writePicture(OutputStream out, String siteID){
      try{
          Class.forName(dbDriver);
          dbConnection = DriverManager.getConnection(dbURL, userID, passwd);
          PreparedStatement stmt = dbConnection.prepareStatement("select * from webcatalog where ID = ?");
          stmt.setString(1,siteID);
          stmt.executeQuery();
          ResultSet rs = stmt.getResultSet();
          if (rs.next()) {
              byte[] data = rs.getBytes("Picture");
              if (data != null) {
                  Image inImage = new ImageIcon(data).getImage();
                  BufferedImage outImage = new BufferedImage(inImage.getWidth(null),
                                                             inImage.getHeight(null),
                                                             BufferedImage.TYPE_INT_RGB);
                  // Paint image.
                  Graphics2D g2d = outImage.createGraphics();
                  g2d.drawImage(inImage,null,null);
                  // JPEG-encode the image
                  JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
                  encoder.encode(outImage);
                  out.close();
          rs.close();
          stmt.close();
          dbConnection.close();
      }catch(Exception ex){
          ex.printStackTrace();
  public void writeThumbnailPicture(OutputStream out,String siteID,int maxDimension){
    try{
      Class.forName(dbDriver);
      dbConnection = DriverManager.getConnection(dbURL, userID, passwd);
      PreparedStatement stmt = dbConnection.prepareStatement("select * from webcatalog where ID = ?");
      stmt.setString(1,siteID);
      stmt.executeQuery();
      ResultSet rs = stmt.getResultSet();
      if (rs.next()) {
        byte[] data = rs.getBytes("Picture");
        if (data != null) {
          Image inImage = new ImageIcon(data).getImage();
          // Determine the scale.
           double scale = (double)maxDimension / (double)inImage.getHeight(null);
           if (inImage.getWidth(null) > inImage.getHeight(null)) {
               scale = (double)maxDimension /(double)inImage.getWidth(null);
           // Determine size of new image.
           // One of them should equal maxDim.
           int scaledW = (int)(scale*inImage.getWidth(null));
           int scaledH = (int)(scale*inImage.getHeight(null));
           // Create an image buffer in
           //which to paint on.
           BufferedImage outImage = new BufferedImage(scaledW, scaledH,
               BufferedImage.TYPE_INT_RGB);
           // Set the scale.
           AffineTransform tx = new AffineTransform();
           // If the image is smaller than
           // the desired image size,
           // don't bother scaling.
           if (scale < 1.0d) {
               tx.scale(scale, scale);
           // Paint image.
           Graphics2D g2d = outImage.createGraphics();
           g2d.drawImage(inImage, tx, null);
           g2d.dispose();
           // JPEG-encode the image
           JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
           encoder.encode(outImage);
           out.close();
      rs.close();
      stmt.close();
      dbConnection.close();
    catch(Exception ex){
      ex.printStackTrace();
  //Clean up resources
  public void destroy() {
  private void jbInit() throws Exception {
}

Answer 1

you can try this:
open your connection outside the function, and then pass it like as a parameter...
writePicture(OutputStream out, String siteID, Connection conn)
this can solve the problem because opening the connection inside the function spends a lot of memory...
Hope this can help you
Regards
Fernando