arthas/arthas-tutorials-en/command/dump/dump.md

Dump the bytecode for the particular classes to the specified directory.

dump command Docs

Usage

Loading class bytecode without specifying a directory

dump java.lang.String{{execute T2}}

dump demo.*{{execute T2}}

Loading class bytecode with specifying a directory

dump -d /tmp/output java.lang.String{{execute T2}}

• Specify classLoader Note that the hashcode changes, you need to check the current ClassLoader information first, and extract the hashcode corresponding to the ClassLoader.
  if you use-c{{}} , you have to manually type hashcode by -c <hashcode>{{}} .
  For classloader with only one instance, it can be specified by --classLoaderClass{{}} using class name, which is more convenient to use.

dump --classLoaderClass jdk.internal.loader.ClassLoaders$AppClassLoader demo.*{{execute T2}}

• PS: Here the classLoaderClass in java 8 is sun.misc.Launcher$AppClassLoader, while in java 11 it's jdk.internal.loader.ClassLoaders$AppClassLoader. Currently killercoda using java 11.

The value of --classloaderclass{{}} is the class name of classloader. It can only work when it matches a unique classloader instance. The purpose is to facilitate the input of general commands. However, -c <hashcode>{{}} is dynamic.