jvm-证明cpu指令是乱序执行的案例

package jvm;/*** 证明cpu指令是乱序执行的** @author 1* @version 1.0* @description: TODO* @date 2024-07-19 9:31*/
public class T04_Disorder {private static int x = 0, y = 0;private static int a = 0, b =0;public static void main(String[] args) throws InterruptedException {int i = 0;for(;;) {i++;x = 0; y = 0;a = 0; b = 0;Thread one = new Thread(new Runnable() {@Overridepublic void run() {//由于线程one先启动，下面这句话让它等一等线程two. 读着可根据自己电脑的实际性能适当调整等待时间.//shortWait(100000);a = 1;x = b;}});Thread other = new Thread(new Runnable() {@Overridepublic void run() {b = 1;y = a;}});one.start();other.start();one.join();other.join();String result = "第" + i + "次 (" + x + "," + y + "）";//如果cpu是顺序指令执行的,那么上面两个线程,要么a=1则y=1或者b=1则x=1 也就是x和y不可能同时为0 除非 线程没有按照顺序执行if(x == 0 && y == 0) {System.err.println(result);break;} else {//System.out.println(result);}}}public static void shortWait(long interval){long start = System.nanoTime();long end;do{end = System.nanoTime();}while(start + interval >= end);}
}

执行结果:  第1661256次 (0,0）

证明了,cpu指令的确是乱序执行的;