监控项目，资源。 https://docs.oracle.com/javase/1.5.0/docs/api/java/lang/management/MemoryMXBean.html https://juejin.im/post/5acf4f936fb9a028e46f085e https://docs.oracle.com/javase/7/docs/jre/api/management/extension/com/sun/management/GarbageCollectionNotificationInfo.html http://hllvm.group.iteye.com/group/topic/38227 https://www.ibm.com/developerworks/cn/java/j-rtm1/ init / used / committed / max 内存状态描述 https://docs.oracle.com/javase/9/docs/api/java/lang/management/MemoryUsage.html