High performance, high resilient JSP and servlet optimization

Is your Java application running very slowly? Can they afford to keep up with the rising traffic? This article describes the development of high-performance, highly resilient JSP pages and the performance optimization of the servlet technology. The idea is to build as fast as possible and adapt to a growing number of users and their requests. In this article, I'm going to take you through the performance tuning techniques that have been practiced and proven, which will greatly improve the performance of your servlet and JSP pages, and hence the performance of Java EE. Parts of these technologies are used in the development phase, such as the design and coding phases. Another part of the technology is related to configuration.

Technology 1: Caching data in the HttpServlet init () method

The servlet's init () method is invoked by the server after the servlet instance is created and before any requests are processed by the servlet. This method is invoked only once in the life cycle of the servlet. To improve performance, cache static data in init () or complete costly operations to complete during initialization. For example, a best practice is to use a JDBC connection pool that implements the Javax.sql.DataSource interface. DataSource is obtained from the Jndi tree. Using Jndi to find DataSource every time you invoke SQL is a very expensive task and severely affects the performance of your application. The init () method of the servlet can be used to get datasource and cache it for later reuse:

public class ControllerServlet extends HttpServlet
　　{
　　　 private javax.sql.DataSource testDS = null;

　　　 public void init(ServletConfig config) throws ServletException
　　　 {
　　　　　super.init(config);
　　　　　Context ctx　= null;
　　　　　try
　　　　　{
　　　　　　 ctx = new InitialContext();
　　　　　　 testDS = (javax.sql.DataSource)ctx.lookup("jdbc/testDS");
　　　　　}
　　　　　catch(NamingException ne)
　　　　　{
　　　　　　 ne.printStackTrace();
　　　　　 }
　　　　　 catch(Exception e)
　　　　　 {
　　　　　　　e.printStackTrace();
　　　　　 }
　　　 }

　　　 public javax.sql.DataSource getTestDS()
　　　　　{
　　　　　　 return testDS;
　　　　　}
　　　 ...
　　　 ...
　　}

Technology 2: Disable automatic loading of servlet and JSP

After each modification of servlet/jsp, you will have to reboot the server. This feature is considered useful in the development phase because of the reduced development time by the automatic loading feature. However, it is very expensive at run time; servlet/jsp due to unnecessary loading, it increases the burden of class loaders and results in poor performance. Again, this will make your application strange conflicts occur because classes that have been loaded by a type loader cannot collaborate with classes that are loaded by the current class loader. Therefore, in order to get better performance in the running environment, turn off the servlet/jsp automatic loading function.

Technology 3: Control HttpSession

Many applications require a range of client requests, so they can be associated with each other. Because the HTTP protocol is stateless, web-based applications need to be responsible for maintaining such a state called session. To support applications that must maintain state, the Java servlet technology provides an API for managing sessions and allowing multiple mechanisms to implement sessions. The HttpSession object acts as a session, but it costs money to use it. Whenever HttpSession is used and rewritten, it is read by the servlet. You can improve performance by using the following techniques:

Do not create a default httpsession in a JSP page: By default, JSP pages create httpsession. If you are not httpsession in a JSP page, to save performance overhead, use the following page instructions to avoid automatically creating HttpSession objects:

　< %@ page session="false"%>

Do not store large object graphs in HttpSession: If you store data as a large object graph in HttpSession, the application server will have to process the entire HttpSession object at a time. This will force Java serialization and increase the computational overhead. Due to the cost of serialization, the throughput of the system decreases as the data objects in the HttpSession object are increased.

Release HttpSession after use: When HttpSession is not used, the Httpsession.invalidate () method is used to invalidate sesion.

Set timeout value: A servlet engine has a default timeout value. If you do not delete the session or use the session until it times out, the servlet engine will remove the session from memory. Because of the overhead on memory and garbage collection, the greater the timeout value of the session, the greater the impact on system elasticity and performance. Try setting the timeout value for the session as low as possible.