java内存模型

https://www.cnblogs.com/shen-qian/p/11277085.html

参考：

1. https://www.jianshu.com/p/a79b3174c2fb
2. https://blog.youkuaiyun.com/shijian4810/article/details/84821356
3. https://www.cnblogs.com/secbro/p/11718987.html