alibaba/arthas

支持启动时增强/trace/watch类

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#2170 opened on May 7, 2022

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 (1 comment) (0 reactions) (0 assignees)Java (37,305 stars) (7,637 forks)batch import
disscusshelp wanted

Description

目前arthas的工作方式是主动的，当执行命令时，从jvm搜索所有加载的类，做一次增强。

  • 如果命令执行时，类还没被加载，则搜索不到，也就是不起作用
  • 如果命令执行成功后，又加载新的类，也会匹配不到

考虑一种Listener的模式，可以预先设定匹配的表达式，如果有匹配的类被加载时，就会触发增强。

难点在于怎么和现有的机制结合起来。

Contributor guide

Tech stack
java
Domain
observability
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
4
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
over 1 week
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
mostly clear
Prerequisites
Understanding of Java class loadingFamiliarity with Arthas internalsKnowledge of bytecode instrumentation
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
20
Research direction
Investigate the Arthas class enhancement mechanism in the core module, particularly how the Transformer intercepts class loading. The current implementation only enhances classes already loaded. The issue suggests adding a listener pattern to pre register matching criteria for future load events. Look into the existing command execution flow and the class loading hooks available in Java Instrumentation API. There are no linked PRs or comments; the solution requires designing a new registration and matching system.