code: // from gee.cs.oswego.edu/home/jsr166/jsr166
  
  package jsr166tests.jtreg.util.concurrent.BlockingQueue;
  
  /*
   * Written by Doug Lea with assistance from members of JCP JSR-166
   * Expert Group and released to the public domain, as explained at
   * http://creativecommons.org/licenses/publicdomain
   */
  
  /*
   * @test
   * @bug 4486658
   * @compile -source 1.5 MultipleProducersSingleConsumerLoops.java
   * @run main/timeout=3600 MultipleProducersSingleConsumerLoops
   * @summary  multiple producers and single consumer using blocking queues
   */
  
  import java.util.concurrent.*;
  
  public class MultipleProducersSingleConsumerLoops {
      static final int CAPACITY =      100;
      static final ExecutorService pool = Executors.newCachedThreadPool();
      static boolean print = false;
      static int producerSum;
      static int consumerSum;
  
      static synchronized void addProducerSum(int x) {
          producerSum += x;
      }
  
      static synchronized void addConsumerSum(int x) {
          consumerSum += x;
      }
  
      static synchronized void checkSum() {
          if (producerSum != consumerSum)
              throw new Error("CheckSum mismatch");
      }
  
      public static void main(String[] args) throws Exception {
          int maxProducers = 5;
          int iters = 100000;
  
          if (args.length > 0)
              maxProducers = Integer.parseInt(args[0]);
  
          print = false;
          System.out.println("Warmup...");
          oneTest(1, 10000);
          Thread.sleep(100);
          oneTest(2, 10000);
          Thread.sleep(100);
          print = true;
  
          for (int i = 1; i <= maxProducers; i += (i+1) >>> 1) {
              System.out.println("----------------------------------------");
              System.out.println("Producers:" + i);
              oneTest(i, iters);
              Thread.sleep(100);
          }
          pool.shutdown();
          if (! pool.awaitTermination(Long.MAX_VALUE, TimeUnit.NANOSECONDS))
              throw new Error();
     }
  
      static void oneTest(int producers, int iters) throws Exception {
          oneRun(new ArrayBlockingQueue<Integer>(CAPACITY), producers, iters);
          oneRun(new LinkedBlockingQueue<Integer>(CAPACITY), producers, iters);
          oneRun(new LinkedBlockingDeque<Integer>(CAPACITY), producers, iters);
          //oneRun(new LinkedTransferQueue<Integer>(), producers, iters);
  
          // Don't run PBQ since can legitimately run out of memory
          //        if (print)
          //            System.out.print("PriorityBlockingQueue   ");
          //        oneRun(new PriorityBlockingQueue<Integer>(), producers, iters);
  
          oneRun(new SynchronousQueue<Integer>(), producers, iters);
          if (print)
              System.out.println("fair implementations:");
          oneRun(new SynchronousQueue<Integer>(true), producers, iters);
          oneRun(new ArrayBlockingQueue<Integer>(CAPACITY, true), producers, iters);
      }
  
      static abstract class Stage implements Runnable {
          final int iters;
          final BlockingQueue<Integer> queue;
          final CyclicBarrier barrier;
          Stage (BlockingQueue<Integer> q, CyclicBarrier b, int iters) {
              queue = q;
              barrier = b;
              this.iters = iters;
          }
      }
  
      static class Producer extends Stage {
          Producer(BlockingQueue<Integer> q, CyclicBarrier b, int iters) {
              super(q, b, iters);
          }
  
          public void run() {
              try {
                  barrier.await();
                  int s = 0;
                  int l = hashCode();
                  for (int i = 0; i < iters; ++i) {
                      l = LoopHelpers.compute1(l);
                      l = LoopHelpers.compute2(l);
                      queue.put(new Integer(l));
                      s += l;
                  }
                  addProducerSum(s);
                  barrier.await();
              }
              catch (Exception ie) {
                  ie.printStackTrace();
                  return;
              }
          }
      }
  
      static class Consumer extends Stage {
          Consumer(BlockingQueue<Integer> q, CyclicBarrier b, int iters) {
              super(q, b, iters);
          }
  
          public void run() {
              try {
                  barrier.await();
                  int s = 0;
                  for (int i = 0; i < iters; ++i) {
                      s += queue.take().intValue();
                  }
                  addConsumerSum(s);
                  barrier.await();
              }
              catch (Exception ie) {
                  ie.printStackTrace();
                  return;
              }
          }
  
      }
  
      static void oneRun(BlockingQueue<Integer> q, int nproducers, int iters) throws Exception {
          if (print)
              System.out.printf("%-18s", q.getClass().getSimpleName());
          LoopHelpers.BarrierTimer timer = new LoopHelpers.BarrierTimer();
          CyclicBarrier barrier = new CyclicBarrier(nproducers + 2, timer);
          for (int i = 0; i < nproducers; ++i) {
              pool.execute(new Producer(q, barrier, iters));
          }
          pool.execute(new Consumer(q, barrier, iters * nproducers));
          barrier.await();
          barrier.await();
          long time = timer.getTime();
          checkSum();
          if (print)
              System.out.println("\t: " + LoopHelpers.rightJustify(time / (iters * nproducers)) + " ns per transfer");
      }
  
  }
  