[JVM] 如何查看当前使用的JVM参数

我就是我 2022-08-31 13:22 190阅读 0赞

### 前言 ###

在开发过程中遇到需要查看JVM参数. 以及使用的GC垃圾回收器的类型. 本次将其记录于此.

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### 方法1 查看默认设置 ###

使用`java -XX:+PrintCommandLineFlags -version`即可.

localhost:redis sean$ java -XX:+PrintCommandLineFlags -version
    -XX:InitialHeapSize=134217728 -XX:MaxHeapSize=2147483648 -XX:+PrintCommandLineFlags -XX:+UseCompressedClassPointers -XX:+UseCompressedOops -XX:+UseParallelGC
    java version "1.8.0_102"
    Java(TM) SE Runtime Environment (build 1.8.0_102-b14)
    Java HotSpot(TM) 64-Bit Server VM (build 25.102-b14, mixed mode)

*  `UseParallelGC`: 其中使用的垃圾回收器为JDK1.8 . `UseParallelGC`表示在年轻代使用`ParallelGC`老年代使用`ParallelOld`.

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### 方法2 使用jinfo命令查看指定线程参数 ###

*  `jps -lm` : 查看当前指定进程号.
 *  `jinfo -flags <pid>`: 查看某个Java进程使用的JVM参数.

# jps
    localhost:redis sean$ jps -lm
    1969 sun.tools.jps.Jps -lm
    1777 com.yanxml.redis.cluster.TestJava
    1506
    
    # jinfo
    localhost:redis sean$ jinfo -flags 1777
    Attaching to process ID 1777, please wait...
    Debugger attached successfully.
    Server compiler detected.
    JVM version is 25.102-b14
    Non-default VM flags: -XX:CICompilerCount=3 -XX:InitialHeapSize=134217728 -XX:MaxHeapSize=576716800 -XX:MaxNewSize=191889408 -XX:MinHeapDeltaBytes=524288 -XX:NewSize=44564480 -XX:OldSize=89653248 -XX:+UseCompressedClassPointers -XX:+UseCompressedOops -XX:+UseFastUnorderedTimeStamps -XX:+UseParallelGC
    Command line:  -Xmx550m -javaagent:/Users/sean/Software/IDEA/IntelliJ IDEA.app/Contents/lib/idea_rt.jar=51235:/Users/sean/Software/IDEA/IntelliJ IDEA.app/Contents/bin -Dfile.encoding=UTF-8

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### 示例程序及参数 ###

package com.yanxml.redis.cluster;
    
    public class TestJava {
    
        public static void main(String[] args) throws InterruptedException {
            Thread.sleep(1000*1000);
        }
    
    }

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTA0MTYxMDE_size_16_color_FFFFFF_t_70]

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### Reference ###

\[1\]. [如何查看正在运行中的JVM采用哪种GC算法策略][JVM_GC]  
\[2\] [JVM垃圾回收查看、分析和设置][JVM]  
\[3\] [JVM学习笔记3：GC日志和常用命令工具][JVM_3_GC]

--------------------

### Others ###

[Java垃圾收集器——Parallel、G1收集器日志分析及性能调优示范][Java_Parallel_G1]  
[JVM调优总结 -Xms -Xmx -Xmn -Xss][JVM_ -Xms -Xmx -Xmn -Xss]  
[GC四种类型][GC]  
[java 默认参数\_查看JVM默认参数值命令][java _JVM]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTA0MTYxMDE_size_16_color_FFFFFF_t_70]: /images/20220829/da49bb52482649eeadc5750757821dfa.png
[JVM_GC]: https://blog.csdn.net/liangcheng0523/article/details/106341325?spm=1001.2014.3001.5501
[JVM]: https://blog.csdn.net/Rudolf__
[JVM_3_GC]: https://www.cnblogs.com/Zafkiel/p/10611017.html
[Java_Parallel_G1]: https://www.cnblogs.com/jason1990/p/11736779.html
[JVM_ -Xms -Xmx -Xmn -Xss]: https://www.cnblogs.com/likehua/p/3369823.html
[GC]: https://www.cnblogs.com/maokun/articles/7618472.html
[java _JVM]: https://blog.csdn.net/weixin_39922868/article/details/114232463