java JVM JMM

总览：
https://blog.csdn.net/laomo_bible/article/details/83067810
区分：
https://blog.csdn.net/qq_36907589/article/details/80839385
JMM具体描述：
https://blog.csdn.net/lkforce/article/details/81128115#%E4%BA%8C%EF%BC%8C%E5%AE%9E%E4%BE%8B%E6%95%B0%E6%8D%AE