diff --git a/docs/jvm/problem-tools.md b/docs/jvm/problem-tools.md index bc341922ec76b2446a6791cab30e75495b81492c..d67dbbf68a17bb64eab550f2eb14c41930e2bdc4 100644 --- a/docs/jvm/problem-tools.md +++ b/docs/jvm/problem-tools.md @@ -271,17 +271,225 @@ jinfo可以用来查看正在运行的java运用程序的扩展参数,甚至 ## 8、可视化监控工具(JConsole、JVisualVM) -集上面之大成,并提供了可视化的界面;还可以监控远程Java服务;支持监控JMX。 +### 简介 -JVisualVM比JConsole更强大:支持对CPU、内存运行进行采样、配置。推荐用JVisualVM。 +在 JDK 安装目录的 `bin` 文件夹下,除了提供有命令行监控工具外,还提供了几种可视化的监控工具,以方便用户直观地了解虚拟机的运行状态。常用的可视化监控工具如下: -JConsole监控页面示例: +### JConsole -![](https://cdn.jsdelivr.net/gh/itwanger/toBeBetterJavaer/images/jvm/problem-tools-7fa6b7b2-28bf-46cb-8d52-5fe3cb75240a.png) +#### 简介 -JVisualVM监控页面示例: +JConsole(Java Monitoring and Management Console)是一款基于 JMX(Java Manage-ment Extensions)的可视化监视工具。它的主要功能是通过 JMX 的 MBean(Managed Bean)对系统信息进行收集和动态调整系统参数。JMX(Java Management Extensions)是一个为应用程序、设备、系统等植入管理功能的框架,通常用于监控系统的运行状态或管理系统的部分功能。 -![](https://cdn.jsdelivr.net/gh/itwanger/toBeBetterJavaer/images/jvm/problem-tools-dca6e1d0-f345-4e21-83b3-e0cf82e3d79a.png) +#### 使用 + +打开位于 bin 目录下的 `jconsole` 程序后,它会自动扫描当前主机上的所有 JVM 进程: + +![](https://cdn.jsdelivr.net/gh/itwanger/toBeBetterJavaer/images/jvm/problem-tools-6b614bd9-5e75-48e0-b51e-50cbd33669a5.png) + + +选中需要监控的进程后,点击连接,即可进入监控界面。监控界面包含了 *概览*、*内存*、*线程*、*类*、*VM 概要*、*MBean* 六个选项卡。其中概览界面显示的是 *内存*、*线程*、*类* 等三个选项卡界面的概览信息,如下所示: + +![](https://cdn.jsdelivr.net/gh/itwanger/toBeBetterJavaer/images/jvm/problem-tools-10f3df05-e209-4bca-a8dc-99668a2d8e07.png) + + + + +而内存界面主要用于显示堆和非堆上各个区域的使用量: + + + +![](https://cdn.jsdelivr.net/gh/itwanger/toBeBetterJavaer/images/jvm/problem-tools-ddabe66e-18ac-4cb6-9e9e-f446645a4501.png) + + + + +线程界面内主要显示各个线程的堆栈信息,最下角有一个 **检测死锁** 按钮,点击后如果检测到死锁存在,则在下部的线程选项卡旁边会出现死锁选项卡: + + + +![](https://cdn.jsdelivr.net/gh/itwanger/toBeBetterJavaer/images/jvm/problem-tools-a97902be-6084-4009-81b2-cbe08d60a617.png) + + + + +点击死锁选项卡则可以看到造成死锁的线程: + +![](https://cdn.jsdelivr.net/gh/itwanger/toBeBetterJavaer/images/jvm/problem-tools-a76f6714-0efd-4208-a203-9264bc9963d9.png) + + + + +最后的 **类** 选项卡主要用于显示当前已加载和已卸载的类的数量。而 **VM 概要** 选项卡则主要用于显示虚拟机的相关参数,如下所示: + + + +![](https://cdn.jsdelivr.net/gh/itwanger/toBeBetterJavaer/images/jvm/problem-tools-519acfd8-943e-4005-b1af-9de1e4187971.png) + + + + +### VisualVM + +#### 简介 + +VisualVM(All-in-One Java Troubleshooting Tool)是 Oracle 提供的功能最强大的运行监视和故障处理程序之一, 它除了支持常规的运行监视、故障处理等功能外,还能用于性能分析(Profiling)。同时因为 VisualVM 是基于 NetBeans 平台的开发工具,所以它还支持通过插件来进行功能的拓展。VisualVM 的主要功能如下: + +- 显示虚拟机进程及其配置信息、环境信息(与 jps、jinfo 功能类似); +- 监视应用程序的处理器、垃圾收集、堆、方法区以及线程的信息(与 jstat、jstack 功能类似); +- dump以及分析堆转储快照(与 jmap、jhat 功能类似); +- 方法级的程序运行性能分析,找出被调用最多、运行时间最长的方法; +- 离线程序快照:可以收集程序的运行时配置、线程 dump、内存 dump 等信息来建立快照。 + +#### 使用 + +打开位于 bin 目录下的 `jvisualvm` 程序, 它会自动扫描当前主机上的所有 JVM 进程: + +![](https://cdn.jsdelivr.net/gh/itwanger/toBeBetterJavaer/images/jvm/problem-tools-221c1e6e-bcfd-4bf3-be85-6172a3f72962.png) + + + + +点击需要监控的进程后,右侧即会显示相关的监控信息: + + + +![](https://cdn.jsdelivr.net/gh/itwanger/toBeBetterJavaer/images/jvm/problem-tools-0e0a833a-d13c-4b70-b7ee-c58651a58185.png) + + + + +**1. 堆 Dump** + +在监控界面点击按钮可以 **执行垃圾回收** 或者 **堆 Dump** 。进行堆 Dump 后,还会显示其分析结果: + + + +![](https://cdn.jsdelivr.net/gh/itwanger/toBeBetterJavaer/images/jvm/problem-tools-afaf433c-6ae7-4c4b-b686-48504cd4c3e9.png) + + + + +**2. 线程 Dump** + +在线程界面可以查看所有线程的状态,如果出现死锁,该界面还会进行提示: + +![](https://cdn.jsdelivr.net/gh/itwanger/toBeBetterJavaer/images/jvm/problem-tools-9dbc6b53-c9e6-4051-845f-ef2d848b5d60.png) + + + + +此时可以进行 **线程 Dump** 来获取具体的线程信息,效果和 jstack 命令类似: + + + +![](https://cdn.jsdelivr.net/gh/itwanger/toBeBetterJavaer/images/jvm/problem-tools-74941c88-d009-4d7f-8264-efc7d94c94ee.png) + + + + +**3. 性能分析** + +在 Profiler 界面,可以进行 CPU 和 内存的性能分析。要开始性能分析,需要先选择 **CPU** 或 **内存** 按钮中的一个,VisualVM 将会开始记录应用程序执行过的所有方法:如果是进行的是 CPU 执行时间分析,将会统计每个方法的执行次数、执行耗时;如果是内存分析,则会统计每个方法关联的对象数以及这些对象所占的空间。想要结束性能分析,点击停止按钮即可: + +![](https://cdn.jsdelivr.net/gh/itwanger/toBeBetterJavaer/images/jvm/problem-tools-946d7f3e-9519-4a0b-8905-0bf2c1d83fcb.png) + + + + +**4. Visual GC** + +Visual GC 面板默认是不显示的,需要通过插件进行扩展。它会实时监控虚拟机的状态,在功能上类似于 jstat 命令: + +![](https://cdn.jsdelivr.net/gh/itwanger/toBeBetterJavaer/images/jvm/problem-tools-b6f23234-8b1d-44df-8b12-e723dc0d1903.png) + + + + +#### 安装插件 + +在主界面,点击 **工具 => 插件** ,可以打开插件面板。右击插件选项或者点击安装按钮即可完成对应插件的安装: + +![](https://cdn.jsdelivr.net/gh/itwanger/toBeBetterJavaer/images/jvm/problem-tools-4518bc2f-ef1f-4ed6-8da9-47a0fdc03338.png) + + + + +需要注意的是,安装插件前需要按照自己 JVM 的版本来配置插件中心,否则会抛出 ”无法连接到插件中心“ 的异常。每个版本对应的插件中心可以在该网址上查看:https://visualvm.github.io/pluginscenters.html,界面如下: + + + +![](https://cdn.jsdelivr.net/gh/itwanger/toBeBetterJavaer/images/jvm/problem-tools-146f715c-a902-4725-9101-07d608a04770.png) + + + + +之后需要将正确的插件中心的地址配置到程序中: + + + +![](https://cdn.jsdelivr.net/gh/itwanger/toBeBetterJavaer/images/jvm/problem-tools-55919d48-88f4-4ee5-842f-3ed20b9f7cd6.png) + + + + +### 连接远程进程 + +以上演示 JConsole 和 VisualVM 时,我们都是用的本地进程,但在实际开发中,我们更多需要监控的是服务器上的远程进程。想要监控远程主机上的进程,需要进行 JMX 的相关配置,根据连接时是否需要用户名和密码,可以分为以下两种配置方式: + +#### 不使用安全凭证 + +启动服务器上的 Java 进程时增加以下参数: + +```shell + java -Dcom.sun.management.jmxremote.port=12345 #jmx远程连接的端口号 + -Dcom.sun.management.jmxremote.ssl=false + -Dcom.sun.management.jmxremote.authenticate=false + -jar springboot.jar +``` + +此时只需要知道主机地址和端口号就可以连接,不需要使用用户名和密码,所以安全性比较低。 + +#### 使用安全凭证 + +启动服务器上的 Java 进程时增加以下参数: + +```shell +java -Dcom.sun.management.jmxremote.port=12345 +-Dcom.sun.management.jmxremote.ssl=false +-Dcom.sun.management.jmxremote.authenticate=true +-Dcom.sun.management.jmxremote.access.file=/usr/local/jmxremote.access +-Dcom.sun.management.jmxremote.password.file=/usr/local/jmxremote.password +-jar springboot.jar +``` + +其中 `jmxremote.access ` 的内容如下,其中 admin 为用户名,readwrite 表示可读可写,也可以设置为 readonly(只读): + +```shell +admin readwrite +``` + + `jmxremote.password` 的内容如下,其中 admin 为用户名,123456 为密码: + +```shell +admin 123456 +``` + +两个文件创建好后,还需要赋予其执行权限: + +```shell +chmod 600 /usr/local/jmxremote.access +chmod 600 /usr/local/jmxremote.password +chown root:root /usr/local/jmxremote.access +chown root:root /usr/local/jmxremote.password +``` + +之后在使用 VisualVM 进行远程连接时,配置如下: + +![](https://cdn.jsdelivr.net/gh/itwanger/toBeBetterJavaer/images/jvm/problem-tools-f84f1b0a-3ff7-444f-8285-709a234ce670.png) + + +需要注意的是这里的端口号是配置的 `Dcom.sun.management.jmxremote.port` 的值,而不是 Java 程序的端口号。连接完成后,即可查看到对应进程的监控状态。 ## 其他工具  @@ -342,6 +550,7 @@ CPU使用情况:top 命令 Java程序问题分析:jmap 分析堆内存、jstack 分析线程栈等,见前文。 -原文链接:https://www.cnblogs.com/z-sm/p/6745375.html +- 参考链接 1:[https://www.cnblogs.com/z-sm/p/6745375.html](https://www.cnblogs.com/z-sm/p/6745375.html) +- 参考链接:[https://github.com/heibaiying/Full-Stack-Notes/blob/master/notes/JVM_性能监控之可视化工具.md](https://github.com/heibaiying/Full-Stack-Notes/blob/master/notes/JVM_性能监控之可视化工具.md) - +![](http://cdn.tobebetterjavaer.com/tobebetterjavaer/images/xingbiaogongzhonghao.png) diff --git a/docs/jvm/zongjie.md b/docs/jvm/zongjie.md index fc28ffce77608a37d58ae713935dd87d13c478a4..ac440424d8ce9e2e1ec585caadfcb86f510c31b0 100644 --- a/docs/jvm/zongjie.md +++ b/docs/jvm/zongjie.md @@ -571,6 +571,7 @@ public static String concat(String... strings) { 对于虚拟机执行子系统来说,每次数组元素的读写都带有一次隐含的上下文检查以避免访问越界。如果数组的访问发生在循环之中,并且使用循环变量来访问数据,即循环变量的取值永远在 [0,list.length) 之间,那么此时就可以消除整个循环的数据边界检查,从而避免多次无用的判断。 -原文链接:https://github.com/heibaiying/Full-Stack-Notes +>- 原文链接:[https://github.com/heibaiying/Full-Stack-Notes](https://github.com/heibaiying/Full-Stack-Notes) +>- 整理:沉默王二 - \ No newline at end of file +![](http://cdn.tobebetterjavaer.com/tobebetterjavaer/images/xingbiaogongzhonghao.png) \ No newline at end of file diff --git a/images/jvm/problem-tools-0e0a833a-d13c-4b70-b7ee-c58651a58185.png b/images/jvm/problem-tools-0e0a833a-d13c-4b70-b7ee-c58651a58185.png new file mode 100644 index 0000000000000000000000000000000000000000..cf48a7d1687fff6aaf719f8eb94e545842ffd16a Binary files /dev/null and b/images/jvm/problem-tools-0e0a833a-d13c-4b70-b7ee-c58651a58185.png differ diff --git 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