#获取PID
jps 或者 jcmd
#输出线程信息
jcmd $PID Thread.print > aaa3.log
#查看系统中类统计信息GC.class_histogram
#执行如下命令:
jcmd $PID GC.class_histogram
#其他支持命令
jcmd $PID help
https://stackoverflow.com/questions/29605436/why-java8-server-jre-do-not-contain-server-specific-tools-like-jstack-jmap-jvi