/*
 * Copyright (c) 2007-2010 by The Broad Institute, Inc. and the Massachusetts Institute of Technology.
 * All Rights Reserved.
 *
 * This software is licensed under the terms of the GNU Lesser General Public License (LGPL), Version 2.1 which
 * is available at http://www.opensource.org/licenses/lgpl-2.1.php.
 *
 * THE SOFTWARE IS PROVIDED "AS IS." THE BROAD AND MIT MAKE NO REPRESENTATIONS OR WARRANTIES OF
 * ANY KIND CONCERNING THE SOFTWARE, EXPRESS OR IMPLIED, INCLUDING, WITHOUT LIMITATION, WARRANTIES
 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, NONINFRINGEMENT, OR THE ABSENCE OF LATENT
 * OR OTHER DEFECTS, WHETHER OR NOT DISCOVERABLE.  IN NO EVENT SHALL THE BROAD OR MIT, OR THEIR
 * RESPECTIVE TRUSTEES, DIRECTORS, OFFICERS, EMPLOYEES, AND AFFILIATES BE LIABLE FOR ANY DAMAGES OF
 * ANY KIND, INCLUDING, WITHOUT LIMITATION, INCIDENTAL OR CONSEQUENTIAL DAMAGES, ECONOMIC
 * DAMAGES OR INJURY TO PROPERTY AND LOST PROFITS, REGARDLESS OF WHETHER THE BROAD OR MIT SHALL
 * BE ADVISED, SHALL HAVE OTHER REASON TO KNOW, OR IN FACT SHALL KNOW OF THE POSSIBILITY OF THE
 * FOREGOING.
 */

/*
 * Simple class to time the overhead of splitting a long running job into
 * multiple threads.  On a Macbook Pro the overhead is ~ 20%.  
 */

package org.broad.igv.util;

/**
 * @author jrobinso
 */
public class TestThreadTiming {

    static class Compute implements Runnable {

        int nRepeats;

        Compute(int nRepeats) {
            this.nRepeats = nRepeats;
        }

        public void run() {
            double sum = 0.0;
            for (int i = 0; i < nRepeats; i++) {
                //sum += i * Math.random();
                sum += 1000000.5d;
            }
            System.out.println("Done: " + sum);
        }

    }

    public static void main(String[] args) {

        int nRepeats = 10000000;

        // First test -- one thread
        Compute c1 = new Compute(nRepeats);
        long t0 = System.currentTimeMillis();
        c1.run();
        long dt = System.currentTimeMillis() - t0;
        System.out.println("Single threaded time: " + dt);

        // Second pass -- 10 threads
        t0 = System.currentTimeMillis();
        int nThreads = 10;
        Thread[] workerThreads = new Thread[10];
        for (int i = 0; i < nThreads; i++) {
            Compute c2 = new Compute(nRepeats / nThreads);
            workerThreads[i] = new Thread(c2);
            workerThreads[i].start();
        }

        // Wait for workers to complete
        try {
            for (int i = 0; i < nThreads; i++) {
                workerThreads[i].join();
            }

        } catch (InterruptedException ex) {
            ex.printStackTrace();
        }

        dt = System.currentTimeMillis() - t0;
        System.out.println("Multi threaded time:" + dt);
    }

}
