handle background threads ourselves, leave the stateless pool intact

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

@@ -2,8 +2,6 @@ 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;
@@ -11,12 +9,16 @@ import javax.ejb.ConcurrencyManagement;
 import javax.ejb.ConcurrencyManagementType;
 import javax.ejb.Singleton;
 import javax.ejb.Startup;
+import javax.enterprise.inject.Instance;
 import javax.inject.Inject;
 
 import org.apache.commons.lang.mutable.MutableBoolean;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import scala.actors.threadpool.ExecutorService;
+import scala.actors.threadpool.Executors;
+
 import com.commafeed.backend.dao.FeedCategoryDAO;
 import com.commafeed.backend.dao.FeedDAO;
 import com.commafeed.backend.dao.FeedSubscriptionDAO;
@@ -26,7 +28,6 @@ import com.commafeed.backend.model.ApplicationSettings;
 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
@@ -56,12 +57,11 @@ public class StartupBean {
 	ApplicationSettingsService applicationSettingsService;
 
 	@Inject
-	FeedRefreshWorker worker;
-
-	private List<Future<Void>> threads = Lists.newArrayList();
+	Instance<FeedRefreshWorker> workers;
 
 	private long startupTime;
 
+	private ExecutorService executor;
 	private MutableBoolean running = new MutableBoolean(true);
 
 	@PostConstruct
@@ -72,11 +72,19 @@ public class StartupBean {
 		}
 
 		ApplicationSettings settings = applicationSettingsService.get();
-		log.info("Starting {} background threads",
-				settings.getBackgroundThreads());
-		for (int i = 0; i < settings.getBackgroundThreads(); i++) {
-			Future<Void> thread = worker.start(running, "Thread " + i);
-			threads.add(thread);
+		int threads = settings.getBackgroundThreads();
+		log.info("Starting {} background threads", threads);
+
+		executor = Executors.newFixedThreadPool(threads);
+		for (int i = 0; i < threads; i++) {
+			final int threadId = i;
+			executor.execute(new Runnable() {
+				@Override
+				public void run() {
+					FeedRefreshWorker worker = workers.get();
+					worker.start(running, "Thread " + threadId);
+				}
+			});
 		}
 
 	}
@@ -96,6 +104,14 @@ public class StartupBean {
 	@PreDestroy
 	public void shutdown() {
 		running.setValue(false);
+		executor.shutdownNow();
+		while (!executor.isTerminated()) {
+			try {
+				Thread.sleep(100);
+			} catch (InterruptedException e) {
+				log.error("interrupted while waiting for threads to finish.");
+			}
+		}
 	}
 
 }

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

@@ -2,13 +2,7 @@ package com.commafeed.backend.feeds;
 
 import java.util.Calendar;
 import java.util.Date;
-import java.util.concurrent.Future;
 
-import javax.ejb.AsyncResult;
-import javax.ejb.Asynchronous;
-import javax.ejb.Stateless;
-import javax.ejb.TransactionAttribute;
-import javax.ejb.TransactionAttributeType;
 import javax.inject.Inject;
 import javax.transaction.HeuristicMixedException;
 import javax.transaction.HeuristicRollbackException;
@@ -26,8 +20,6 @@ import com.commafeed.backend.dao.FeedDAO;
 import com.commafeed.backend.model.Feed;
 import com.commafeed.backend.services.FeedUpdateService;
 
-@Stateless
-@TransactionAttribute(TransactionAttributeType.NOT_SUPPORTED)
 public class FeedRefreshWorker {
 
 	private static Logger log = LoggerFactory
@@ -45,8 +37,7 @@ public class FeedRefreshWorker {
 	@Inject
 	FeedRefreshTaskGiver taskGiver;
 
-	@Asynchronous
-	public Future<Void> start(MutableBoolean running, String threadName) {
+	public void start(MutableBoolean running, String threadName) {
 		log.info("{} starting", threadName);
 		while (running.isTrue()) {
 			Feed feed = null;
@@ -59,6 +50,9 @@ public class FeedRefreshWorker {
 					log.debug("sleeping");
 					Thread.sleep(15000);
 				}
+			} catch (InterruptedException e) {
+				log.info(threadName + " interrupted");
+				return;
 			} catch (Exception e) {
 				String feedUrl = "feed is null";
 				if (feed != null) {
@@ -69,7 +63,6 @@ public class FeedRefreshWorker {
 						e);
 			}
 		}
-		return new AsyncResult<Void>(null);
 	}
 
 	private void update(Feed feed) throws NotSupportedException,