java volatile 关键字实战

package com.geekbang.learnvolatile; public class AccessMemoryVolatile { public volatile long counterV = 0; public long counter = 0; public static void main(String[] args) { int loopCount = Integer.MAX_VALUE / 30; // TODO 只是为了演示 volatile 每次访问都要直达内存，不能使用缓存，所以耗费的时间略多 AccessMemoryVolatile accessMemoryVolatile = new AccessMemoryVolatile(); Thread volatileAdder = new Thread(() -> { long start = System.currentTimeMillis(); for (int i = 0; i < loopCount; i++) { accessMemoryVolatile.counterV++; } System.out.println("volatile adder takes " + (System.currentTimeMillis() - start)); }); volatileAdder.start(); Thread justAdder = new Thread(() -> { long start = System.currentTimeMillis(); for (int i = 0; i < loopCount; i++) { accessMemoryVolatile.counter++; } System.out.println("simple adder takes " + (System.currentTimeMillis() - start)); }); justAdder.start(); } }