NMT, Native Memory Tracking

NMT, Native Memory Tracking

NMT for Hotspot VM is turned off by default. Turn this feature on using JVM command line option

-XX:NativeMemoryTracking=[off | summary | detail]

注意,根据Java官方文档,开启NMT会有5%－10%的性能损耗；

访问NMT数据

JDK提供了jcmd命令来访问NMT数据:

jcmd <pid> VM.native_memory [summary | detail | baseline | summary.diff | detail.diff | shutdown] [scale= KB | MB | GB]

配置项 说明

summary 只打印打印按分类汇总的内存

detail 打印按分类汇总的内存用法、virtual memory map和每次内存分配调用

baseline 创建内存快照,以比较不同时间的内存差异

summary.diff 打印自上次baseline到现在的内存差异,显示汇总信息

detail.diff 打印自上次baseline到现在的内存差异, 显示详细信息

shutdown 关闭NMT功能,NMT can be shutdown using jcmd utility, but can not start/restart using jcmd

scale 指定内存单位,默认为KB

  
./jcmd PID VM.native_memory baseline
  

http://www.voidcn.com/blog/jicahoo/article/p-5727258.html

http://blog.csdn.net/jicahoo/article/details/50933469

https://docs.oracle.com/javase/8/docs/technotes/guides/troubleshoot/tooldescr007.html

http://www.jianshu.com/p/7fce29433171

https://docs.oracle.com/javase/8/docs/technotes/guides/troubleshoot/tooldescr022.html#BABHIFJC

http://docs.oracle.com/javase/8/docs/technotes/guides/troubleshoot/tooldescr.html

维护记录