【阿里之Arthas 介绍】

Arthas is a Java Diagnostic tool open sourced by Alibaba.


Arthas 是Alibaba开源的Java诊断工具，深受开发者喜爱。


当你遇到以下类似问题而束手无策时，Arthas可以帮助你解决：


这个类从哪个 jar 包加载的？为什么会报各种类相关的 Exception？

我改的代码为什么没有执行到？难道是我没 commit？分支搞错了？

遇到问题无法在线上 debug，难道只能通过加日志再重新发布吗？

线上遇到某个用户的数据处理有问题，但线上同样无法 debug，线下无法重现！

是否有一个全局视角来查看系统的运行状况？

有什么办法可以监控到JVM的实时运行状态？

怎么快速定位应用的热点，生成火焰图？


Background

Often times, the production system network is inaccessible from the local development environment. If issues are encountered in production systems, it is impossible to use IDEs to debug the application remotely. More importantly, debugging in production environment is unacceptable, as it will suspend all the threads, resulting in the suspension of business services.


Developers could always try to reproduce the same issue on the test/staging environment. However, this is tricky as some issues cannot be reproduced easily on a different environment, or even disappear once restarted.


And if you're thinking of adding some logs to your code to help troubleshoot the issue, you will have to go through the following lifecycle; test, staging, and then to production. Time is money! This approach is inefficient! Besides, the issue may not be reproducible once the JVM is restarted, as described above.


Arthas was built to solve these issues. A developer can troubleshoot your production issues on-the-fly. No JVM restart, no additional code changes. Arthas works as an observer, which will never suspend your existing threads.


Key features

Check whether a class is loaded, or where the class is being loaded. (Useful for troubleshooting jar file conflicts)

Decompile a class to ensure the code is running as expected.

View classloader statistics, e.g. the number of classloaders, the number of classes loaded per classloader, the classloader hierarchy, possible classloader leaks, etc.

View the method invocation details, e.g. method parameter, return object, thrown exception, and etc.

Check the stack trace of specified method invocation. This is useful when a developers wants to know the caller of the said method.

Trace the method invocation to find slow sub-invocations.

Monitor method invocation statistics, e.g. qps, rt, success rate and etc.

Monitor system metrics, thread states and cpu usage, gc statistics, and etc.

Supports command line interactive mode, with auto-complete feature enabled.

Supports telnet and websocket, which enables both local and remote diagnostics with command line and browsers.

Supports profiler/Flame Graph

Supports JDK 6+.

Supports Linux/Mac/Windows.