Often times, the production system network is inaccessible from local development environment. If issues are encountered in production systems, it is impossible to use IDE to debug the application remotely. More importantly, debugging in production environment is unacceptable, as it will suspend all the threads, which leads to blocking 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 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 trouble-shoot 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 trouble-shoot 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.
* View classloader statistics, e.g. the number of classloaders, the number of classes loaded per classloader, the classloader hierarchy, possible classloader leaks, etc.
English version has just been finished. If you would like to make it better, please check [here](https://github.com/alibaba/arthas/issues/51) and submit your PM.
