OnJava8-Examples/tasks/SimpleMicroBenchmark.java

// tasks/SimpleMicroBenchmark.java
// (c)2016 MindView LLC: see Copyright.txt
// We make no guarantees that this code is fit for any purpose.
// Visit http://mindviewinc.com/Books/OnJava/ for more book information.
// The dangers of microbenchmarking
import java.util.concurrent.locks.*;

abstract class Incrementable {
  protected long counter = 0;
  public abstract void increment();
}

class SynchronizingTest extends Incrementable {
  @Override
  public synchronized void increment() { ++counter; }
}

class LockingTest extends Incrementable {
  private Lock lock = new ReentrantLock();
  @Override
  public void increment() {
    lock.lock();
    try {
      ++counter;
    } finally {
      lock.unlock();
    }
  }
}

public class SimpleMicroBenchmark {
  static long test(Incrementable incr) {
    long start = System.nanoTime();
    for(long i = 0; i < 10000000L; i++)
      incr.increment();
    return System.nanoTime() - start;
  }
  public static void main(String[] args) {
    long synchTime = test(new SynchronizingTest());
    long lockTime = test(new LockingTest());
    System.out.printf(
      "synchronized: %1$10d\n", synchTime);
    System.out.printf("Lock:         %1$10d\n", lockTime);
    System.out.printf("Lock/synchronized = %1$.3f",
      (double)lockTime/(double)synchTime);
  }
}
/* Output:
synchronized:  243572959
Lock:          365176719
Lock/synchronized = 1.499
*/