Arthas基本使用

### 下载和安装
```shell
# 下载
curl -O https://arthas.aliyun.com/arthas-boot.jar
# 运行
java -jar arthas-boot.jar
```

查看 dashboard

输入dashboard，按回车/enter，会展示当前进程的信息，按ctrl+c可以中断执行。

```txt
processors                                                     2
ID   NAME                            GROUP           PRIORITY  STATE      %CPU      DELTA_TIME TIME      INTERRUPTE DAEMON
-1   C1 CompilerThread1              -               -1        -          0.29      0.014      0:2.298   false      true
-1   C2 CompilerThread0              -               -1        -          0.1       0.004      0:10.857  false      true
-1   VM Periodic Task Thread         -               -1        -          0.08      0.004      0:0.253   false      true

Memory                     used     total    max      usage    GC
heap                       197M     357M     839M     23.47%   gc.ps_scavenge.count            15
ps_eden_space              136M     275M     281M     48.65%   gc.ps_scavenge.time(ms)         465
ps_survivor_space          13M      13M      13M      96.62%   gc.ps_marksweep.count           3
ps_old_gen                 47M      68M      629M     7.51%    gc.ps_marksweep.time(ms)        227
nonheap                    121M     125M     -1       96.58%
code_cache                 21M      22M      240M     9.11%
metaspace                  88M      92M      -1       96.12%
compressed_class_space     10M      11M      1024M    1.07%
direct                     16K      16K      -        100.01%
mapped                     19M      19M      -        100.00%
Runtime
os.name                                                        Linux
os.version                                                     3.10.0-1160.71.1.el7.x86_64
java.version                                                   1.8.0_372
java.home                                                      /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.372.b07-1.el7_9.x86_64/j
                                                               re
systemload.average                                             0.00
processors                                                     2

```
### 通过 jad 来反编译Class
	jad 类的全路径名（包名+类名）

例如

$ jad demo.MathGame

### watch

watch 全路径类名 方法名 返回值

通过watch命令来查看com.speechb.controller.Web.WebUrlController#index函数的返回值：

watch com.speechb.controller.Web.WebUrlController index returnObj

### trace 函数

trace 全路径类名 方法名
例如

trace com.speechb.controller.Web.WebUrlController index