arthas/arthas-tutorials-en/command/mc-redefine/mc.md

Memory compiler, compiles .java{{}} files into .class{{}} files in memory.

mc command Docs

The classloader can be specified with the -c{{}} /--classLoaderClass{{}} option, the output directory can be specified with the -d{{}} option.

After compiling the .class{{}} file, you can use the redefine command to re-define the loaded classes in JVM.