volatile/non-volatile/unsafe read test

gistfile1.txt

import java.lang.reflect.Field;
import java.security.SecureRandom;

import sun.misc.Unsafe;

public class Test2 {
	
	static final Unsafe unsafe;
	static final long offsetA;
	static final long offsetB;
	
	static {
		Unsafe unsafeInit;
	    try {
	        @SuppressWarnings("unchecked")
			Class<Unsafe> unsafeClass = (Class<Unsafe>) Class.forName("sun.misc.Unsafe");
	        Field unsafeField = unsafeClass.getDeclaredField("theUnsafe");
	        unsafeField.setAccessible(true);
	        unsafeInit = (Unsafe) unsafeField.get(unsafeClass);
	    }
	    catch (Exception e) {
	       unsafeInit = null;
	    }
	    
	    unsafe = unsafeInit;
	    
	    Field a = null;
		Field b = null;
		try
		{
			a = Test2.class.getDeclaredField("var1a");
			b = Test2.class.getDeclaredField("var1b");
		} catch (NoSuchFieldException | SecurityException e)
		{
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	    
    	offsetA = unsafeInit.objectFieldOffset(a);
		offsetB = unsafeInit.objectFieldOffset(b);
	}
	
	public Test2() {
		// TODO Auto-generated constructor stub
	}
	
	static volatile long escapeHatch;
	
	volatile long[] var1a = new long[40];
	volatile long[] var1b = new long[40];
	
	final long[] var2a = new long[40];
	final long[] var2b = new long[40];
	
	SecureRandom rand = new SecureRandom();
	
	static final int iterations = 90000000;
	
	void prep(long[] a, long[] b) {
		for(int i = 0;i<a.length;i++)
		{
			a[i] = rand.nextLong();
			b[i] = rand.nextLong();
		}
	}
	
	void test1() {
		long counter = 0;
		
		for(int i=0;i<iterations;i++)
			counter += var1a[0]+= var1b[13]++;
		
		escapeHatch = counter;
	}
	
	void test2() {
		long counter = 0;
		
		for(int i=0;i<iterations;i++)
			counter += var2a[0]+= var2b[13]++;
		
		escapeHatch = counter;
	}
	
	void test3() {
		long counter = 0;
		
		for(int i=0;i<iterations;i++)
			counter += ((long[])unsafe.getObject(this, offsetA))[0]+= ((long[])unsafe.getObject(this, offsetB))[13]++;

		escapeHatch = counter;
	}
	
	public static void main(String[] args) throws InterruptedException {
		final Test2 t = new Test2();
		
		
		
		Runnable runner1 = new Runnable() {
			@Override
			public void run() {
				for(int i=0;i<10;i++)
				{
					t.prep(t.var1a, t.var1b);
					long time = System.currentTimeMillis();
					t.test1();
					System.out.println("t1 " + (System.currentTimeMillis() - time));
				}
			}
		};

		Runnable runner2 = new Runnable() {
			@Override
			public void run() {
				for(int i=0;i<10;i++)
				{
					t.prep(t.var2a, t.var2b);
					long time = System.currentTimeMillis();
					t.test2();
					System.out.println("t2 " + (System.currentTimeMillis() - time));
				}
			}
		};
		
		Runnable runner3 = new Runnable() {
			@Override
			public void run() {
				for(int i=0;i<10;i++)
				{
					t.prep(t.var1a, t.var1b);
					long time = System.currentTimeMillis();
					t.test3();
					System.out.println("t3 " + (System.currentTimeMillis() - time));				}
			}
		};

		
		Thread t1a = new Thread(runner1);
		Thread t1b = new Thread(runner1);
		Thread t2a = new Thread(runner2);
		Thread t2b = new Thread(runner2);
		Thread t3a = new Thread(runner3);
		Thread t3b = new Thread(runner3);
		
		t1a.start();
		//t1b.start();
		t1a.join();
		t2a.start();
		//t2b.start();
		t2a.join();
		t3a.start();
		//t3b.start();
		

	}
	
}