Preload Application Modules?

Question

Is there a suggested technique for preloading application modules when the web application start up in the app server? We currently have about 25 application modules, most of which are rather small. However, a few of them contain a large number of views so these load very slowly on the first access. Thanks to AM pooling, all subsequent accesses are very fast. If we could preload these larger AMs when the application server starts, that would be ideal.
Thanks,
Bryan

Answer 1

Hi,
The BC4J application pool does support an initial pool size which, when greater than zero, will cause that number of ApplicationModule(s) to be asynchronously created in the application pool. See the documentation for jbo.ampool.initpoolsize for more information.
One wrinkle that you may have encountered when using this property is that the initializer thread (instantiates the AM(s)) is not launched until the pool is actually created, which, for a web application, typically won't occur until the first request. In order to perform this before the first request you could implement logic in a ServletContextListener which instantiates the pool(s) required by the application using oracle.jbo.common.ampool.PoolMgr.findPool:
public class BootstrapListener implements ServletContextListener
private ServletContext context = null;
public void contextInitialized(ServletContextEvent event)
context = event.getServletContext();
PoolMgr.getInstance().findPool(
"Mypackage1ModuleLocal" // pool name, should match the config name if using BC4J JSP datatags
, "mypackage1" // configuration package name
, "Mypackage1ModuleLocal" // configuration name
, null); // additional pool properties
public void contextDestroyed(ServletContextEvent event)
context = event.getServletContext();
Hope this helps,
JR