JVM 监控工具——JConsole

落日映苍穹つ 2022-09-08 00:12 308阅读 0赞

# 一 点睛 #

jconsole：从 Java5 开始，在 JDK 中自带的 java 监控和管理控制台。

用于对 JVM 中内存、线程和类等的监控，是一个基于 JMX（java management extensions）的 GUI 性能监控工具。

官方地址：[https://docs.oracle.com/javase/7/docs/technotes/guides/management/jconsole.html][https_docs.oracle.com_javase_7_docs_technotes_guides_management_jconsole.html]

工具位置

![20210824181039523.png][]

# 二 实战——基本测试 #

## 1 代码 ##

package chapter03;
    
    import java.util.ArrayList;
    import java.util.Random;
    
    /**
    * -Xms600m -Xmx600m -XX:SurvivorRatio=8
    * 老年代：400m
    * 伊甸园：160m
    * s0:20m
    * s1:20m
    */
    public class HeapInstanceTest {
        byte[] buffer = new byte[new Random().nextInt(1024 * 100)];
    
        public static void main(String[] args) {
            try {
                Thread.sleep(3000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            ArrayList<HeapInstanceTest> list = new ArrayList<>();
            while (true) {
                list.add(new HeapInstanceTest());
                try {
                    Thread.sleep(10);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
    }

## 2 运行程序后通过 jconsole 进行连接 ##

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NoZW5ncWl1bWluZw_size_16_color_FFFFFF_t_70][]

## 3 概览 ##

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NoZW5ncWl1bWluZw_size_16_color_FFFFFF_t_70 1][]

## 4 内存 ##

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NoZW5ncWl1bWluZw_size_16_color_FFFFFF_t_70 2][]

## 5 线程 ##

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NoZW5ncWl1bWluZw_size_16_color_FFFFFF_t_70 3][]

## 6 类 ##

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NoZW5ncWl1bWluZw_size_16_color_FFFFFF_t_70 4][]

## 7 VM 概要 ##

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NoZW5ncWl1bWluZw_size_16_color_FFFFFF_t_70 5][]

# 三 实战——检测死锁 #

## 1 代码 ##

package chaper02;
    
    /**
    * @className: ThreadDeadLock
    * @description: 线程死锁
    * @date: 2021/8/22
    */
    public class ThreadDeadLock {
        public static void main(String[] args) {
            StringBuilder s1 = new StringBuilder();
            StringBuilder s2 = new StringBuilder();
            new Thread() {
                public void run() {
                    synchronized (s1) {
                        s1.append("a");
                        s2.append("1");
    
    
                        try {
                            Thread.sleep(100);
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
    
                        synchronized (s2) {
                            s1.append("b");
                            s2.append("2");
    
    
                            System.out.println(s1);
                            System.out.println(s2);
                        }
                    }
                }
            }.start();
    
            new Thread() {
                public void run() {
                    synchronized (s2) {
                        s1.append("c");
                        s2.append("3");
    
                        try {
                            Thread.sleep(100);
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
    
                        synchronized (s1) {
                            s1.append("d");
                            s2.append("4");
                            System.out.println(s1);
                            System.out.println(s2);
                        }
                    }
                }
            }.start();
        }
    }

## 2 测试 ##

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NoZW5ncWl1bWluZw_size_16_color_FFFFFF_t_70][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NoZW5ncWl1bWluZw_size_16_color_FFFFFF_t_70 4][]

[https_docs.oracle.com_javase_7_docs_technotes_guides_management_jconsole.html]: https://docs.oracle.com/javase/7/docs/technotes/guides/management/jconsole.html
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