# Online trouble-shooting with Arthas (1)

Arthas from Alibaba, is an online trouble-shooting tool.

No JVM restart, no additional code changes. Arthas works as an observer, that is, it will never suspend your running threads.

Launching Arthas:

$java -jar arthas-boot.jar  Then select the application to be monitored. Stop Arthas: $ quit


or

$exit  Basic Commands: 1. dashboard command $ dashboard


The dashboard command allows you to view the real-time data panel of the current system.

$thread 1  The thread 1 command prints the stack of thread ID 1. Arthas supports pipes, and you can find main class with thread 1 | grep 'main('. 1. sc command $ sc -d *MathGame


The sc command can be used to find the loaded classes in the JVM

$jad demo.MathGame  The jad command can be used to decompile the byte code 1. watch command $ watch demo.MathGame primeFactors returnObj

The watch command can view the parameter/return value/exception of the method.
params refers to parameters
-x 2 means the print depth is 2