options

options在线教程

::: tip 全局开关 :::

名称	默认值	描述
unsafe	false	是否支持对系统级别的类进行增强，打开该开关可能导致把 JVM 搞挂，请慎重选择！
dump	false	是否支持被增强了的类 dump 到外部文件中，如果打开开关，class 文件会被 dump 到`/${application working dir}/arthas-class-dump/`目录下，具体位置详见控制台输出
batch-re-transform	true	是否支持批量对匹配到的类执行 retransform 操作
json-format	false	是否支持 json 化的输出
disable-sub-class	false	是否禁用子类匹配，默认在匹配目标类的时候会默认匹配到其子类，如果想精确匹配，可以关闭此开关
support-default-method	true	是否支持匹配到 default method，默认会查找 interface，匹配里面的 default method。参考 #1105
save-result	false	是否打开执行结果存日志功能，打开之后所有命令的运行结果都将保存到`~/logs/arthas-cache/result.log`中
job-timeout	1d	异步后台任务的默认超时时间，超过这个时间，任务自动停止；比如设置 1d, 2h, 3m, 25s，分别代表天、小时、分、秒
print-parent-fields	true	是否打印在 parent class 里的 filed
verbose	false	是否打印更多详细信息
strict	true	是否启用 strict 模式

查看所有的 options

$ options
 LEVEL  TYPE    NAME          VALUE   SUMMARY               DESCRIPTION
-------------------------------------------------------------------------------------------------------
 0      boolea  unsafe        false   Option to support sy  This option enables to proxy functionality
        n                             stem-level class       of JVM classes. Due to serious security r
                                                            isk a JVM crash is possibly be introduced.
                                                             Do not activate it unless you are able to
                                                             manage.
 1      boolea  dump          false   Option to dump the e  This option enables the enhanced classes t
        n                             nhanced classes       o be dumped to external file for further d
                                                            e-compilation and analysis.
 1      boolea  batch-re-tra  true    Option to support ba  This options enables to reTransform classe
        n       nsform                tch reTransform Clas  s with batch mode.
                                      s
 2      boolea  json-format   false   Option to support JS  This option enables to format object outpu
        n                             ON format of object   t with JSON when -x option selected.
                                      output
 1      boolea  disable-sub-  false   Option to control in  This option disable to include sub class w
        n       class                 clude sub class when  hen matching class.
                                       class matching
 1      boolea  support-defa  true    Option to control in  This option disable to include default met
        n       ult-method            clude default method  hod in interface when matching class.
                                       in interface when c
                                      lass matching
 1      boolea  save-result   false   Option to print comm  This option enables to save each command's
        n                             and's result to log    result to log file, which path is ${user.
                                      file                  home}/logs/arthas-cache/result.log.
 2      String  job-timeout   1d      Option to job timeou  This option setting job timeout,The unit c
                                      t                     an be d, h, m, s for day, hour, minute, se
                                                            cond. 1d is one day in default
 1      boolea  print-parent  true    Option to print all   This option enables print files in parent
        n       -fields               fileds in parent cla  class, default value true.
                                      ss
 1      boolea  verbose       false   Option to print verb  This option enables print verbose informat
        n                             ose information       ion, default value false.
 1      boolea  strict        true    Option to strict mod  By default, strict mode is true, not allow
        n                             e                     ed to set object properties. Want to set o
                                                            bject properties, execute `options strict
                                                            false`

获取 option 的值

$ options json-format
 LEVEL  TYPE  NAME         VALUE  SUMMARY             DESCRIPTION
--------------------------------------------------------------------------------------------
 2      bool  json-format  false  Option to support   This option enables to format object
        ean                       JSON format of obj  output with JSON when -x option selec
                                  ect output          ted.

::: tip 默认情况下json-format为 false，如果希望watch/tt等命令结果以 json 格式输出，则可以设置json-format为 true。 :::

设置指定的 option

例如，想打开执行结果存日志功能，输入如下命令即可：

$ options save-result true
 NAME         BEFORE-VALUE  AFTER-VALUE
----------------------------------------
 save-result  false         true

打开 unsafe 开关，支持 jdk package 下的类

默认情况下，watch/trace/tt/trace/monitor等命令不支持java.* package 下的类。可以设置unsafe为 true，则可以增强。

$ options unsafe true
 NAME    BEFORE-VALUE  AFTER-VALUE
-----------------------------------
 unsafe  false         true

$ watch java.lang.invoke.Invokers callSiteForm
Press Q or Ctrl+C to abort.
Affect(class count: 1 , method count: 1) cost in 61 ms, listenerId: 1

关闭 strict 模式，允许在 ognl 表达式里设置对象属性

::: tip since 3.6.0 :::

对于新用户，在编写 ognl 表达式时，可能会出现误用。

比如对于Student，判断年龄等于 18 时，可能条件表达式会误写为target.age=18，这个表达式实际上是把当前对象的age设置为 18 了。正确的写法是target.age==18。

为了防止出现类似上面的误用，Arthas 默认启用strict模式，在ognl表达式里，禁止更新对象的 Property 或者调用setter函数。

以MathGame为例，会出现以下的错误提示。

$ watch demo.MathGame primeFactors 'target' 'target.illegalArgumentCount=1'
Press Q or Ctrl+C to abort.
Affect(class count: 1 , method count: 1) cost in 206 ms, listenerId: 1
watch failed, condition is: target.illegalArgumentCount=1, express is: target, By default, strict mode is true, not allowed to set object properties. Want to set object properties, execute `options strict false`, visit /Users/admin/logs/arthas/arthas.log for more details.

用户如果确定要在ognl表达式里更新对象，可以执行options strict false，关闭strict模式。

更多信息参考： https://github.com/alibaba/arthas/issues/2128

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