jdk工具

jinfo

jinfo -flag CMSInitiatingOccupancyFraction 515
-XX:CMSInitiatingOccupancyFraction=-1
可以打印一些系统属性

jstat

jstat -gcutil 3359
  S0     S1     E      O      M     CCS    YGC     YGCT    FGC    FGCT     GCT
  0.00  25.14  40.51  71.72  96.27  94.77    107    1.268    16    0.490    1.757
监控虚拟机的基本状况，内存，gc等情况

jps

-l 输出主类的全名
-v 输出jvm参数
-m 输出传递给main函数的参数
-q 只输出本地虚拟机唯一id（lvmid）

jmap

jhat

oracle官方参考

The jhat command parses a java heap dump file and launches a webserver.
 jhat enables you to browse heap dumps using your favorite webbrowser. jhat 
supports pre-designed queries (such as 'show all instances of a known class 
"Foo"') as well as OQL (Object Query Language) - a SQL-like query 
language to query heap dumps. Help on OQL is available from the OQL help page 
shown by jhat. With the default port, OQL help is available at 
http://localhost:7000/oqlhelp/

可以看出，是对jmap dump的数据进行分析。