JSP class loader

Question

          Hi,
          I have a static block within a JSP page that get executed twice when it's being executed!
          Based on the output, you can see that it's being loaded by two separated class loaders:
          'weblogic.utils.classloaders.RecursiveReloadOnModifyClassLoader$Slave' and 'weblogic.servlet.jsp.OneOffJspLoader'.
          Can anyone shed some light on this issue? I can see that this might cause a lot
          of problem if the logic relies on the static block only executing once.
          thanks,
          -vu
          /** Code starts here **/
          <%!
          static
               System.out.println("\n\nThis is the static block!!!!");
               try {
          System.out.println("Static classloader: " +
          Class.forName("jsp_servlet._helloworld").getClassLoader().getClass().getName()
          + "\n\n");
               catch (java.lang.ClassNotFoundException cne) { }
          %>
          <%
               System.out.println("Hello World.");
               System.out.println("Class name: " + this.getClass().getName());
               System.out.println("Class loader: " +
          page.getClass().getClassLoader().getClass().getName());
          %>
          /** code ends here **/
          /** Program's Output to Stdout **/
          This is the static block!!!!
          Static classloader: weblogic.utils.classloaders.RecursiveReloadOnModifyClassLoader$Slave
          This is the static block!!!!
          Static classloader: weblogic.servlet.jsp.OneOffJspLoader
          Hello World.
          Class name: jsp_servlet._helloworld
          Class loader: weblogic.servlet.jsp.OneOffJspLoader
          /** End OUtput **/
          

Answer 1

          Well, I wouldn't say expected - obviously this poster (and others)
          don't expect it, and correct is debatable.
          Why in the *&^%* is it necessary to load the class twice? And I
          don't mean two hours apart either - when you hit a JSP for the
          first time, it gets loaded twice - one right after the other.
          This wastes time and memory. When the JVMs and WLS clusters are
          failing (and they are) because of too much class loading - it is
          a big problem.
          Mike
          "Cameron Purdy" <[email protected]> wrote:
          >Don't rely on static code only being executed once. What
          >you are seeing is
          >not only legal, it is expected and correct behavior.
          >
          >BTW - don't put static blocks in your JSP page. Use lazy
          >initializers that
          >store the result in app scope if you have to.
          >
          >Peace,
          >
          >--
          >Cameron Purdy
          >Tangosol, Inc.
          >http://www.tangosol.com
          >+1.617.623.5782
          >WebLogic Consulting Available
          >
          >
          >"Vu Nguyen" <[email protected]> wrote in message
          >news:[email protected]...
          >>
          >> Hi,
          >>
          >> I have a static block within a JSP page that get executed
          >twice when it's
          >being executed!
          >> Based on the output, you can see that it's being loaded
          >by two separated
          >class loaders:
          >> 'weblogic.utils.classloaders.RecursiveReloadOnModifyClassLoader$Slave'
          >and
          >'weblogic.servlet.jsp.OneOffJspLoader'.
          >> Can anyone shed some light on this issue? I can see
          >that this might
          >cause a lot
          >> of problem if the logic relies on the static block only
          >executing once.
          >>
          >> thanks,
          >> -vu
          >>
          >>
          >>
          >> /** Code starts here **/
          >> <%!
          >> static
          >> {
          >> System.out.println("\n\nThis is the static block!!!!");
          >> try {
          >> System.out.println("Static classloader:
          >" +
          >>
          >Class.forName("jsp_servlet._helloworld").getClassLoader().getClass().getName
          >()
          >> + "\n\n");
          >> }
          >> catch (java.lang.ClassNotFoundException cne) { }
          >> }
          >> %>
          >>
          >> <%
          >> System.out.println("Hello World.");
          >> System.out.println("Class name: " + this.getClass().getName());
          >> System.out.println("Class loader: " +
          >> page.getClass().getClassLoader().getClass().getName());
          >> %>
          >> /** code ends here **/
          >>
          >>
          >> /** Program's Output to Stdout **/
          >> This is the static block!!!!
          >> Static classloader:
          >weblogic.utils.classloaders.RecursiveReloadOnModifyClassLoader$Slave
          >>
          >>
          >>
          >>
          >> This is the static block!!!!
          >> Static classloader: weblogic.servlet.jsp.OneOffJspLoader
          >>
          >>
          >> Hello World.
          >> Class name: jsp_servlet._helloworld
          >> Class loader: weblogic.servlet.jsp.OneOffJspLoader
          >>
          >> /** End OUtput **/
          >
          >