Prentice Hall and Sun Microsystems. Personal use only; do not redistribute.

18.8 Connection Pooling: A Case Study

509

Table 18.1  Connection pool timing results

Condition

Average Time

Fast LAN connection to database, 

1.8 seconds

10 initial connections, 50 max connections 

(

ConnectionPoolServlet

)

Fast LAN connection to database, 

2.0 seconds

recycling a single connection

(

ConnectionPoolServlet2

)

Fast LAN connection to database, no 

2.8 seconds

connection pooling

(

ConnectionPoolServlet3

)

Listing 18.20 ConnectionPoolServlet.java 

package coreservlets;

import java.io.*;

import javax.servlet.*;

import javax.servlet.http.*;

import java.sql.*;

/** A servlet that reads information from a database and

 *  presents it in an HTML table. It uses connection

 *  pooling to optimize the database retrieval. A good

 *  test case is ConnectionPool.html, which loads many

 *  copies of this servlet into different frame cells.

*/

public class ConnectionPoolServlet extends HttpServlet {

  private ConnectionPool connectionPool;

  public void doGet(HttpServletRequest request,

                    HttpServletResponse response)

      throws ServletException, IOException {

    String table;

    try {

      String query =

        "SELECT firstname, lastname " +

        " FROM employees WHERE salary > 70000";

      Connection connection = connectionPool.getConnection();

      DBResults results =

          DatabaseUtilities.getQueryResults(connection,

                                            query, false);

      connectionPool.free(connection);

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