https://www.jianshu.com/p/82cbcabd4ef9 jvm垃圾回收机制
https://www.cnblogs.com/itommy/p/10644584.html https://www.iteye.com/blog/phl-1995506jvm两次标记
https://blog.csdn.net/k741451/article/details/78370407 哪些对象可以视为jvm中的gc root
https://www.cnblogs.com/zhangcaiwang/p/7159452.html Survivor区为什么是两个，不能是0个或1个
https://blog.csdn.net/iva_brother/article/details/87886525 jvm垃圾回集器的介绍
https://blog.csdn.net/rodesad/article/details/51544977 jvm调优参数
https://www.jianshu.com/p/989d3b06a49d jvm动态年龄判定规则