Arthas redefine class case tutorial #847 (#1339)

tutorials/katacoda/case-jad-mc-redefine-cn/arthas-boot.md

@@ -0,0 +1,16 @@
+
+
+
+
+在新的`Terminal 2`里，下载`arthas-boot.jar`，再用`java -jar`命令启动：
+
+`wget https://arthas.aliyun.com/doc/arthas-boot.jar
+java -jar arthas-boot.jar`{{execute T2}}
+
+`arthas-boot`是`Arthas`的启动程序，它启动后，会列出所有的Java进程，用户可以选择需要诊断的目标进程。
+
+选择第一个进程，输入 `1`{{execute T2}} ，再`Enter/回车`：
+
+Attach成功之后，会打印Arthas LOGO。输入 `help`{{execute T2}} 可以获取到更多的帮助信息。
+
+![Arthas Boot](/arthas/scenarios/common-resources/assets/arthas-boot.png)

tutorials/katacoda/case-jad-mc-redefine-cn/case-jad-mc-redefine.md

@@ -0,0 +1,85 @@
+下面介绍通过`jad`/`mc`/`redefine` 命令实现动态更新代码的功能。
+
+目前，访问 http://localhost/user/0 ，会返回500异常：
+
+`curl http://localhost/user/0`{{execute T3}}
+
+```
+{"timestamp":1550223186170,"status":500,"error":"Internal Server Error","exception":"java.lang.IllegalArgumentException","message":"id < 1","path":"/user/0"}
+```
+
+下面通过热更新代码，修改这个逻辑。
+
+### jad反编译UserController
+
+`jad --source-only com.example.demo.arthas.user.UserController > /tmp/UserController.java`{{execute T2}}
+
+jad反编译的结果保存在 `/tmp/UserController.java`文件里了。
+
+再打开一个`Terminal 3`，然后用vim来编辑`/tmp/UserController.java`：
+
+`vim /tmp/UserController.java`{{execute T3}}
+
+比如当 user id 小于1时，也正常返回，不抛出异常：
+
+```java
+    @GetMapping(value={"/user/{id}"})
+    public User findUserById(@PathVariable Integer id) {
+        logger.info("id: {}", (Object)id);
+        if (id != null && id < 1) {
+			return new User(id, "name" + id);
+            // throw new IllegalArgumentException("id < 1");
+        }
+        return new User(id.intValue(), "name" + id);
+    }
+```
+
+### sc查找加载UserController的ClassLoader
+
+`sc -d *UserController | grep classLoaderHash`{{execute T2}}
+
+```bash
+$ sc -d *UserController | grep classLoaderHash
+ classLoaderHash   1be6f5c3
+```
+
+可以发现是 spring boot `LaunchedURLClassLoader@1be6f5c3` 加载的。
+
+请记下你的classLoaderHash，后面需要使用它。在这里，它是 `1be6f5c3`。
+
+注意：请使用你的classLoaderHash值覆盖 `<classLoaderHash>` ，然后手动执行下面所有所述命令：
+
+### mc
+
+保存好`/tmp/UserController.java`之后，使用`mc`(Memory Compiler)命令来编译，并且通过`-c`参数指定ClassLoader：
+
+`mc -c <classLoaderHash> /tmp/UserController.java -d /tmp`
+
+```bash
+$ mc -c 1be6f5c3 /tmp/UserController.java -d /tmp
+Memory compiler output:
+/tmp/com/example/demo/arthas/user/UserController.class
+Affect(row-cnt:1) cost in 346 ms
+```
+
+### redefine
+
+再使用`redefine`命令重新加载新编译好的`UserController.class`：
+
+`redefine /tmp/com/example/demo/arthas/user/UserController.class`{{execute T2}}
+
+```
+$ redefine /tmp/com/example/demo/arthas/user/UserController.class
+redefine success, size: 1
+```
+
+### 热修改代码结果
+
+`redefine`成功之后，再次访问 https://[[HOST_SUBDOMAIN]]-80-[[KATACODA_HOST]].environments.katacoda.com/user/0 ，结果是：
+
+```
+{
+  "id": 0,
+  "name": "name0"
+}
+```

tutorials/katacoda/case-jad-mc-redefine-cn/finish.md

@@ -0,0 +1,10 @@
+
+通过本教程基本掌握了Arthas热更新代码。更多高级特性，可以在下面的进阶指南里继续了解。
+
+* [Arthas进阶](https://arthas.aliyun.com/doc/arthas-tutorials?language=cn&id=arthas-advanced)
+* [Arthas Github](https://github.com/alibaba/arthas)
+* [Arthas 文档](https://arthas.aliyun.com/doc/)
+
+欢迎关注公众号，获取Arthas项目的信息，源码分析，案例实践。
+
+![Arthas公众号](/arthas/scenarios/common-resources/assets/qrcode_gongzhonghao.jpg)

tutorials/katacoda/case-jad-mc-redefine-cn/index.json

@@ -0,0 +1,45 @@
+{
+  "title": "Arthas 热更新代码 案例",
+  "description": "Arthas 热更新代码 案例",
+  "difficulty": "高级使用者",
+  "time": "10分钟",
+  "details": {
+    "steps": [
+      {
+        "title": "Start demo",
+        "text": "start-demo.md"
+      },
+      {
+        "title": "Start arthas-boot",
+        "text": "arthas-boot.md"
+      },
+      {
+        "title": "热更新代码",
+        "text": "case-jad-mc-redefine.md"
+      }
+    ],
+    "intro": {
+      "text": "intro.md"
+    },
+    "finish": {
+      "text": "finish.md"
+    },
+    "assets": {
+      "host01": []
+    }
+  },
+  "environment": {
+    "uilayout": "terminal",
+    "showdashboard": true,
+    "dashboards": [
+      {
+        "name": "Web Port 80",
+        "port": 80
+      }
+    ]
+  },
+  "backend": {
+    "imageid": "java",
+    "environmentsprotocol": "http"
+  }
+}

tutorials/katacoda/case-jad-mc-redefine-cn/intro.md

@@ -0,0 +1,11 @@
+
+
+
+![Arthas](https://arthas.aliyun.com/doc/_images/arthas.png)
+
+`Arthas` 是Alibaba开源的Java诊断工具，深受开发者喜爱。在线排查问题，无需重启；动态跟踪Java代码；实时监控JVM状态。
+
+`Arthas` 支持JDK 6+，支持Linux/Mac/Windows，采用命令行交互模式，同时提供丰富的 `Tab` 自动补全功能，进一步方便进行问题的定位和诊断。
+
+* Github: https://github.com/alibaba/arthas
+* 文档: https://arthas.aliyun.com/doc/

tutorials/katacoda/case-jad-mc-redefine-cn/start-demo.md

@@ -0,0 +1,14 @@
+
+
+
+
+下载`demo-arthas-spring-boot.jar`，再用`java -jar`命令启动：
+
+`wget https://github.com/hengyunabc/spring-boot-inside/raw/master/demo-arthas-spring-boot/demo-arthas-spring-boot.jar
+java -jar demo-arthas-spring-boot.jar`{{execute T1}}
+
+`demo-arthas-spring-boot`是一个很简单的spring boot应用，源代码：[查看](https://github.com/hengyunabc/spring-boot-inside/tree/master/demo-arthas-spring-boot)
+
+启动之后，可以访问80端口： https://[[HOST_SUBDOMAIN]]-80-[[KATACODA_HOST]].environments.katacoda.com
+
+![Demo Web](/arthas/scenarios/common-resources/assets/demo-web.png)

tutorials/katacoda/case-jad-mc-redefine-en/arthas-boot.md

@@ -0,0 +1,16 @@
+
+
+
+
+In the new `Terminal 2`, download `arthas-boot.jar` and start with the `java -jar` command:
+
+`wget https://arthas.aliyun.com/doc/arthas-boot.jar
+java -jar arthas-boot.jar`{{execute T2}}
+
+`arthas-boot` is the launcher for `Arthas`. It lists all the Java processes, and the user can select the target process to be diagnosed.
+
+Select the first process, type `1`{{execute T2}} ，then type `Enter`：
+
+After the Attach is successful, Arthas LOGO is printed. Enter `help`{{execute T2}} for more help.
+
+![Arthas Boot](/arthas/scenarios/common-resources/assets/arthas-boot.png)

tutorials/katacoda/case-jad-mc-redefine-en/case-jad-mc-redefine.md

@@ -0,0 +1,88 @@
+This case introduces the ability to dynamically update code via the `jad`/`mc`/`redefine` command.
+
+Currently, visiting http://localhost/user/0 will return a 500 error:
+
+`curl http://localhost/user/0`{{execute T3}}
+
+```
+{"timestamp":1550223186170,"status":500,"error":"Internal Server Error","exception":"java.lang.IllegalArgumentException","message":"id < 1","path":"/user/0"}
+```
+
+This logic will be modified by `redefine` command below.
+
+### Use jad command to decompile UserController
+
+`jad --source-only com.example.demo.arthas.user.UserController > /tmp/UserController.java`{{execute T2}}
+
+The result of jad command will be saved in the `/tmp/UserController.java` file.
+
+
+Then open `Terminal 3`, use `vim` to edit `/tmp/UserController.java`:
+
+`vim /tmp/UserController.java`{{execute T3}}
+
+For example, when the user id is less than 1, it also returns normally without throwing an exception:
+
+```java
+    @GetMapping(value={"/user/{id}"})
+    public User findUserById(@PathVariable Integer id) {
+        logger.info("id: {}", (Object)id);
+        if (id != null && id < 1) {
+			return new User(id, "name" + id);
+            // throw new IllegalArgumentException("id < 1");
+        }
+        return new User(id.intValue(), "name" + id);
+    }
+```
+
+### Use sc command to find the ClassLoader that loads the UserController
+
+`sc -d *UserController | grep classLoaderHash`{{execute T2}}
+
+```bash
+$ sc -d *UserController | grep classLoaderHash
+ classLoaderHash   1be6f5c3
+```
+
+It can be found that it is loaded by spring boot `LaunchedURLClassLoader@1be6f5c3`.
+
+Please write down your classLoaderHash here, in the case here, it's `1be6f5c3`. It will be used in the future steps.
+
+Note: Please replace `<classLoaderHash>` with your classLoaderHash above, then execute the commands manually in the following steps:
+
+### mc
+
+After saving `/tmp/UserController.java`, compile with the `mc` (Memory Compiler) command and specify the ClassLoader with the `-c` option:
+
+`mc -c <classLoaderHash> /tmp/UserController.java -d /tmp`
+
+```bash
+$ mc -c 1be6f5c3 /tmp/UserController.java -d /tmp
+Memory compiler output:
+/tmp/com/example/demo/arthas/user/UserController.class
+Affect(row-cnt:1) cost in 346 ms
+```
+
+### redefine
+
+Then reload the newly compiled `UserController.class` with the `redefine` command:
+
+`redefine /tmp/com/example/demo/arthas/user/UserController.class`{{execute T2}}
+
+```
+$ redefine /tmp/com/example/demo/arthas/user/UserController.class
+redefine success, size: 1
+```
+
+### Check the results of the hotswap code
+
+After the `redefine` command is executed successfully, visit https://[[HOST_SUBDOMAIN]]-80-[[KATACODA_HOST]].environments.katacoda.com/user/0 again.
+
+The result is:
+
+```
+{
+  "id": 0,
+  "name": "name0"
+}
+```

tutorials/katacoda/case-jad-mc-redefine-en/finish.md

@@ -0,0 +1,6 @@
+
+Through this tutorial, you can know how to Hotswap code. More advanced features can be found in the Advanced Guide below.
+
+* [Arthas Advanced](https://arthas.aliyun.com/doc/arthas-tutorials?language=en&id=arthas-advanced)
+* [Arthas Github](https://github.com/alibaba/arthas)
+* [Arthas Documentation](https://arthas.aliyun.com/doc/en)

tutorials/katacoda/case-jad-mc-redefine-en/index.json

@@ -0,0 +1,45 @@
+{
+  "title": "Arthas Hotswap code",
+  "description": "Arthas Hotswap code",
+  "difficulty": "expert",
+  "time": "10 minutes",
+  "details": {
+    "steps": [
+      {
+        "title": "Start demo",
+        "text": "start-demo.md"
+      },
+      {
+        "title": "Start arthas-boot",
+        "text": "arthas-boot.md"
+      },
+      {
+        "title": "Hotswap code",
+        "text": "case-jad-mc-redefine.md"
+      }  
+    ],
+    "intro": {
+      "text": "intro.md"
+    },
+    "finish": {
+      "text": "finish.md"
+    },
+    "assets": {
+      "host01": []
+    }
+  },
+  "environment": {
+    "uilayout": "terminal",
+    "showdashboard": true,
+    "dashboards": [
+      {
+        "name": "Web Port 80",
+        "port": 80
+      }
+    ]
+  },
+  "backend": {
+    "imageid": "java",
+    "environmentsprotocol": "http"
+  }
+}

tutorials/katacoda/case-jad-mc-redefine-en/intro.md

@@ -0,0 +1,11 @@
+
+
+
+![Arthas](https://arthas.aliyun.com/doc/_images/arthas.png)
+
+`Arthas` is a Java diagnostic tool open-sourced by Alibaba middleware team. Arthas helps developers in trouble-shooting issues in production environment for Java based applications without modifying code or restarting servers.
+
+`Arthas` supports JDK 6+, supports Linux/Mac/Windows.
+
+* Github: https://github.com/alibaba/arthas
+* Documentation: https://arthas.aliyun.com/doc/en

tutorials/katacoda/case-jad-mc-redefine-en/start-demo.md

@@ -0,0 +1,14 @@
+
+
+
+
+Download `demo-arthas-spring-boot.jar`, and start with `java -jar` command:
+
+`wget https://github.com/hengyunabc/spring-boot-inside/raw/master/demo-arthas-spring-boot/demo-arthas-spring-boot.jar
+java -jar demo-arthas-spring-boot.jar`{{execute T1}}
+
+`demo-arthas-spring-boot` is a simple Spring Boot demo, the source code here: [View](https://github.com/hengyunabc/spring-boot-inside/tree/master/demo-arthas-spring-boot)
+
+After booting, access port 80: https://[[HOST_SUBDOMAIN]]-80-[[KATACODA_HOST]].environments.katacoda.com
+
+![Demo Web](/arthas/scenarios/common-resources/assets/demo-web.png)