How to run/manage container background thread in Java EE 7+? - javabeans

Question

Similar to Background Thread for a Tomcat servlet app but I'm looking for a Java EE 7 specific solution.

Answer 1

This is what I finally came up with for WildFly 11 (Java EE 7) without using any configuration changes/additions to beans.xml/web.xml:
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;
import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;
import javax.annotation.Resource;
import javax.ejb.Singleton;
import javax.ejb.Startup;
import javax.enterprise.concurrent.ManagedThreadFactory;
#Startup
#Singleton
public class IndexingTask implements Runnable {
private static final Logger LOG = LoggerFactory.getLogger(IndexingTask.class);
private Thread taskThread = null;
private final CountDownLatch shutdownLatch = new CountDownLatch(1);
#Resource
private ManagedThreadFactory threadFactory;
#PostConstruct
public void postConstruct() {
taskThread = threadFactory.newThread(this);
taskThread.start();
}
#PreDestroy
public void preDestroy(){
shutdownLatch.countDown();
try {
taskThread.join();
} catch (InterruptedException ex) {
LOG.warn("interrupted while waiting for " + taskThread + " to shut down", ex);
}
}
#Override
public void run() {
LOG.info("started");
try {
while (!shutdownLatch.await(100, TimeUnit.MILLISECONDS)) {
}
} catch (InterruptedException ex) {
LOG.warn("", ex);
}
LOG.info("stopped");
}
}
https://javagc.leponceau.org/2017/10/how-to-runmanage-container-background.html
See also Java EE 7 containers: initialize bean at startup without adding it to beans.xml?