ThreadPool.java

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/*******************************************************************************
 * Copyright (c) 2012 Stefan Profanter. All rights reserved. This program and the accompanying
 * materials are made available under the terms of the GNU Public License v3.0 which accompanies
 * this distribution, and is available at http://www.gnu.org/licenses/gpl.html
 * 
 * Contributors: 
 *                              Stefan Profanter - initial API and implementation, Year: 2012
 *                              Andrei Stoica - minor refactor during Google Summer of Code 2014
 ******************************************************************************/
package edu.tum.cs.ias.knowrob.utils;

import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;

public class ThreadPool {

        public static void executeInPool(List<Callable<Void>> threads) {
                executeInPool(threads, -1);
        }
        
        public static void executeInPool(List<Callable<Void>> threads, int numParallel) {
                ExecutorService pool;
                int threadNum = numParallel <= 0 ? Runtime.getRuntime().availableProcessors() * 2 : numParallel;
                pool = Executors.newFixedThreadPool(threadNum);

                try {
                        List<Future<Void>> futures = pool.invokeAll(threads);
                        for (Future<Void> f : futures) {
                                try {
                                        f.get(); // If called thread threw an exception, get will throw an
                                                                // ExecutionException
                                } catch (ExecutionException ex) {
                                        ex.getCause().printStackTrace(); // Print exceptions from called threads if
                                                                                                                // there were any
                                }
                        }
                } catch (InterruptedException e) {
                        e.printStackTrace();
                }
                threads.clear();
                pool.shutdown();
        }
}