java八股文面试[JVM]——JVM性能优化

傷城~ 2024-03-26 23:17 142阅读 0赞

### JVM性能优化指南 ###

![image.png][]

### JVM常用命令 ###

*  jps

> 查看java进程

The jps command lists the instrumented Java HotSpot VMs on the target system. The command is limited to reporting information on JVMs for which it has the access permissions.

*  jinfo

> **（1）实时查看和调整JVM配置参数**

The jinfo command prints Java configuration information for a specified Java process or core file or a remote debug server. The configuration information includes Java system properties and Java Virtual Machine (JVM) command-line flags.

> **（2）查看用法**
> 
> **jinfo -flag name PID 查看某个java进程的name属性的值**

jinfo -flag MaxHeapSize PID 
    jinfo -flag UseG1GC PID

> **3）修改**
> 
> **参数只有被标记为manageable的flags可以被实时修改**

jinfo -flag [+|-] PID
    jinfo -flag <name>=<value> PID

> **（4）查看曾经赋过值的一些参数**

jinfo -flags PID

*  jstat

> **（1）查看虚拟机性能统计信息**

The jstat command displays performance statistics for an instrumented Java HotSpot VM. The target JVM is identified by its virtual machine identifier, or vmid option.

> **（2）查看类装载信息**

jstat -class PID 1000 10   查看某个java进程的类装载信息，每1000毫秒输出一次，共输出10次

> **（3）查看垃圾收集信息**

jstat -gc PID 1000 10

*  jstack

> **（1）查看线程堆栈信息**

The jstack command prints Java stack traces of Java threads for a specified Java process, core file, or remote debug server.

> **（2）用法**

jstack PID

知识来源：马士兵教育

[image.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/11/8bd420c88e124c99a2d26a7571a80081.png