How do I fix a Thread Leak in a JSF application? - jsf-2

Question

I have an ApplicationScoped bean that fires up a separate Thread to do some background work. The Thread has a method for cleanly terminating it called terminate(). If not terminated via that method it runs in an infinite loop, and sleeps for a while if it finds it has nothing to do.
The thing is I am in development mode (Netbeans -> Maven) and each time I recompile the application, the Maven plug-in un-deploys and redeploys the application (most conveniently I must say) but the background Thread from the last deployment hangs around. It eventually terminates with an Exception because it wakes up from its sleep and tries to access a JPA EntityManager that isn't there anymore.
I would prefer to automatically call the terminate() method when the application is stopped. Is there some way to implement a listener that will do that at the JSF 2.0 specification level? If not, how about at the Servlet level?
This is using GlassFish 3.1.1.

Answer 1

Add a #PreDestroy method to you bean which will run when your application is undeployed or stopped and it can stop the background thread, like this:
import javax.annotation.PreDestroy;
import javax.faces.bean.ApplicationScoped;
import javax.faces.bean.ManagedBean;
#ApplicationScoped
#ManagedBean
public class AppBean {
public AppBean() {
System.out.println("new AppBean()");
}
#PreDestroy
public void preDestory() {
// call thread.terminate() here
System.out.println("preDestory");
}
}