cancel threads when application stops/restarts

src/main/java/com/commafeed/backend/StartupBean.java

@@ -2,8 +2,11 @@ package com.commafeed.backend;
 
 import java.util.Arrays;
 import java.util.Calendar;
+import java.util.List;
+import java.util.concurrent.Future;
 
 import javax.annotation.PostConstruct;
+import javax.annotation.PreDestroy;
 import javax.ejb.Singleton;
 import javax.ejb.Startup;
 import javax.inject.Inject;
@@ -24,6 +27,7 @@ import com.commafeed.backend.model.User;
 import com.commafeed.backend.model.UserRole.Role;
 import com.commafeed.backend.services.ApplicationSettingsService;
 import com.commafeed.backend.services.UserService;
+import com.google.api.client.util.Lists;
 
 @Startup
 @Singleton
@@ -53,6 +57,8 @@ public class StartupBean {
 	@Inject
 	FeedRefreshWorker worker;
 
+	private List<Future<Void>> threads = Lists.newArrayList();
+
 	private long startupTime;
 
 	@PostConstruct
@@ -64,7 +70,8 @@ public class StartupBean {
 
 		ApplicationSettings settings = applicationSettingsService.get();
 		for (int i = 0; i < settings.getBackgroundThreads(); i++) {
-			worker.start();
+			Future<Void> thread = worker.start();
+			threads.add(thread);
 		}
 
 	}
@@ -129,4 +136,11 @@ public class StartupBean {
 		return startupTime;
 	}
 
+	@PreDestroy
+	private void shutdown() {
+		for (Future<Void> future : threads) {
+			future.cancel(true);
+		}
+	}
+
 }

src/main/java/com/commafeed/backend/feeds/FeedRefreshWorker.java

@@ -2,9 +2,12 @@ package com.commafeed.backend.feeds;
 
 import java.util.Calendar;
 import java.util.Date;
+import java.util.concurrent.Future;
 
 import javax.annotation.Resource;
+import javax.ejb.AsyncResult;
 import javax.ejb.Asynchronous;
+import javax.ejb.EJBException;
 import javax.ejb.Stateless;
 import javax.ejb.TransactionManagement;
 import javax.ejb.TransactionManagementType;
@@ -46,9 +49,11 @@ public class FeedRefreshWorker {
 	@Resource
 	private UserTransaction transaction;
 
+	private boolean running = true;
+
 	@Asynchronous
-	public void start() {
+	public Future<Void> start() {
-		while (true) {
+		while (running) {
 			try {
 				Feed feed = getNextFeed();
 				if (feed != null) {
@@ -59,9 +64,10 @@ public class FeedRefreshWorker {
 					Thread.sleep(15000);
 				}
 			} catch (Exception e) {
-				log.error(e.getMessage(), e);
+				throw new EJBException(e.getMessage(), e);
 			}
 		}
+		return new AsyncResult<Void>(null);
 	}
 
 	private void update(Feed feed) throws NotSupportedException,
@@ -115,4 +121,5 @@ public class FeedRefreshWorker {
 	private Feed getNextFeed() {
 		return taskGiver.take();
 	}
+
 }