Java CAS机制的一些理解

public class test {
    private static int x;
    public static void main(String[] args) throws InterruptedException {
        Thread task1 = new Thread(){
            @Override
            public void run() {
                super.run();
                for (int i=0; i<1000; i++){
                    x=x+1;
                }
            }
        };
        Thread task2 = new Thread(){
            @Override
            public void run() {
                super.run();
                for (int i=0; i<1000; i++){
                    x=x+1;
                }
            }
        };

        task1.start();
        task2.start();
        task1.join();
        task2.join();
        System.out.println(x);
    }
/*
1006
*///:~

public class test {
    private static AtomicInteger atomicInteger = new AtomicInteger();
    public static void main(String[] args) throws InterruptedException {
        Thread task1 = new Thread(){
            @Override
            public void run() {
                super.run();
                for (int i=0; i<1000; i++){
                    atomicInteger.incrementAndGet();
                }
            }
        };

        Thread task2 = new Thread(){
            @Override
            public void run() {
                super.run();
                for (int i=0; i<1000; i++){
                    atomicInteger.incrementAndGet();
                }
            }
        };

        task1.start();
        task2.start();
        task1.join();
        task2.join();
        System.out.println(atomicInteger.get());
    }
}/*
2000
*///:~

private static final long valueOffset;
...
public final int incrementAndGet() {
    return unsafe.getAndAddInt(this, valueOffset, 1) + 1;
}
...
Unsafe
public final int getAndAddInt(Object var1, long var2, int var4) {
    int var5;
    do {
        var5 = this.getIntVolatile(var1, var2);
    } while(!this.compareAndSwapInt(var1, var2, var5, var5 + var4));

    return var5;
}