Periodic background processing J2EE web app

Question

I have a Java web application hosted on a Tomcat server. This web application serves http requests. Now, I need to execute a Java program that interacts with the database and perform some tasks nightly. This Java program needs to run on its own thread and should not cause Tomcat to crash/terminate for any reason (obviously will have try-catch blocks, but still).

And yeah, I don't want to run a cron job in the background. I want the web application to execute the program at a certain time right after deployment.

How can I do this?

Well, I think Tomcat should be able to handle this. As there could be something that covers the application life cycle just like how we have a servlet life cycle. — i_raqz, Oct 02 '15 at 23:46

score 1 · Answer 1 · edited Oct 03 '15 at 10:33

Look at java Executor Service which can schedule runnable to run periodically at prescribed times:

private ScheduledExecutorService executorService;

@PostConstruct
public void init() {
    executorService = Executors.newSingleThreadScheduledExecutor();
    executorService.scheduleAtFixedRate(this::periodicJob, 1000, 1, TimeUnit.DAYS);
}

private void periodicJob() {
    //load from db, and process
}

Of course you can manipulate the delay and the period.

However, if you can end up in a JavaEE environment (tomee, wildfly, glasfish and the like), you could use the EJB schedule specs:

@Schedule(hour="*/24", persistence=false, info="My scheduled task")
public void doSomethingAwesomeEveryMidnight(){
}

Periodic background processing J2EE web app

1 Answers1