Advanced Usage

Basic

• help - show help info
• cls - clear out the current screen
• session - check details of the current session
• reset - reset all injected/enhanced classes
• version - print the version of the Arthas attaching to the current target process
• quit/exit - exit the current Arthas client without affecting other clients
• shutdown - terminate the Arthas server and all clients

JVM

• dashboard - real-time dashboard for the current system
• thread - thread profile
• jvm - JVM profile
• sysprop - check or modify JVM system properties
• New! getstatic :clap: - check the static properties of classes

class/classloader

• sc - check profiles of the classes loaded by JVM
• sm - check methods’ profile
• dump - dump out the byte code of the loaded classes to specified location
• redefine - load external *.class files and re-define the JVM-loaded classes
• jad - de-compile the specified loaded classes
• classloader - check the inheritance structure, urls, class loading info of class cloader; using classloader to get the url of the resource e.g. java/lang/String.class

monitor/watch/trace - related

Attention: commands here are taking advantage of byte code injection, which means we are using AOP to monitor and analyze the classes. So when using it for online troubleshooting, you’d better explicitly specifically specify the classes and also remember to remove the injected code by shutdown or reset.

• monitor - monitor the class-pattern & method-pattern matched methods’ invoking traces
• watch - watch/monitor methods in data aspect including return values, exceptions and parameters
• trace - track the method calling trace along with the time cost for each call
• stack - print the call stack trace of the current method in a persistent way
• tt - record the arguments and returned value for the methods, history included

options

• options - check or set Arthas global options

pipe

pipe is supported in Arthas, e.g. sm org.apache.log4j.Logger | grep <init>

Commands supported in pipe:

• grep - filtering
• plaintext - remove the color
• wc - line counting

async in background

async will be a great help, when the incident seldom occurs and you are watching it.

• jobs - list all jobs
• kill - forcibly terminate the job
• fg - bring the paused job back to the front
• bg - put the paused job to the background
• tips - a) use > to redirect the output; b) use & to put the job to the background; c) disconnecting the session will not influence the job (the default life is 1 day)

Others

• Web Console - using websocket to connect Arthas
• log the output
• batch
• how to use ognl