vm 参数说明 ：适用于jdk7之前版本 https://www.oracle.com/java/technologies/javase/vmoptions-jsp.html
jdk8 https://docs.oracle.com/javase/8/docs/technotes/tools/windows/java.html
G1（垃圾优先）收集器 https://www.oracle.com/java/technologies/javase/hotspot-garbage-collection.html
G1 参数调整 https://www.oracle.com/cn/technical-resources/articles/java/g1gc.html