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Advanced Usage

Basic

help - display Arthas help
cls - clear the screen
cat - Concatenate and print files
echo - write arguments to the standard output
grep - Pattern searcher
base64 - Encode and decode using Base64 representation.
tee - Copies standard input to standard output, making a copy in zero or more files.
pwd - Return working directory name
session - display current session information
reset - reset all the enhanced classes. All enhanced classes will also be reset when Arthas server is closed by stop
version - print the version for the Arthas attached to the current Java process
history - view command history
quit/exit - exit the current Arthas session, without effecting other sessions
stop - terminate the Arthas server, all Arthas sessions will be destroyed
keymap - keymap for Arthas keyboard shortcut

JVM

dashboard - dashboard for the system's real-time data
thread - show java thread information
jvm - show JVM information
sysprop - view/modify system properties
sysenv — view system environment variables
vmoption - view/modify the vm diagnostic options.
perfcounter - show JVM Perf Counter information
logger - print the logger information, update the logger level
getstatic - examine class's static properties
ognl - execute ognl expression
mbean - show Mbean information
heapdump - dump java heap in hprof binary format, like jmap
vmtool - jvm tool, getInstances in jvm, forceGc

class/classloader

sc - check the info for the classes loaded by JVM
sm - check methods info for the loaded classes
jad - decompile the specified loaded classes
mc - Memory compiler, compiles .java files into .class files in memory
retransform - load external *.class files and retransform it into JVM
redefine - load external *.class files and re-define it into JVM
dump - dump the loaded classes in byte code to the specified location
classloader - check the inheritance structure, urls, class loading info for the specified class; using classloader to get the url of the resource e.g. java/lang/String.class

::: warning Attention: commands here are taking advantage of byte-code-injection, which means we are injecting some aspects into the current classes for monitoring and statistics purpose. Therefore, when using it for online troubleshooting in your production environment, you'd better explicitly specify classes/methods/criteria, and remember to remove the injected code by stop or reset. :::

monitor - monitor method execution statistics
watch - display the input/output parameter, return object, and thrown exception of specified method invocation
trace - trace the execution time of specified method invocation
stack - display the stack trace for the specified class and method
tt - time tunnel, record the arguments and returned value for the methods and replay

authentication

auth - authentication

options

options - check/set Arthas global options

profiler/flame graph

profiler - use async-profiler to generate flame graph

pipe

Arthas provides pipe to process the result returned from commands further, e.g. sm java.lang.String * | grep 'index'. Commands supported in pipe:

grep - filter the result with the given keyword
plaintext - remove the ANSI color
wc - count lines

async jobs

async can be handy when a problem is hardly to reproduce in the production environment, e.g. one watch condition may happen only once in one single day.

job control - use > to redirect result into the log file, use & to put the job to the background. Job keeps running even if the session is disconnected (the session lifecycle is 1 day by default)
jobs - list all jobs
kill - forcibly terminate the job
fg - bring the suspend job to the foreground
bg - put the job to run in the background

Web Console

Arthas supports living inside a browser. The communication between arthas and browser is via websocket.

Web Console

Arthas Properties

Arthas Properties

Start as a Java Agent

Start as a Java Agent

as.sh and arthas-boot tips

Select the process to be attached via the select option.

Normally, as.sh/arthas-boot.jar needs to a pid, bacause the pid will change.

For example, with math-game.jar already started, use the jps command to see.

$ jps
58883 math-game.jar
58884 Jps

The select option allows you to specify a process name, which is very convenient.

$ ./as.sh --select math-game
Arthas script version: 3.3.6
[INFO] JAVA_HOME: /tmp/java/8.0.222-zulu
Arthas home: /Users/admin/.arthas/lib/3.3.6/arthas
Calculating attach execution time...
Attaching to 59161 using version /Users/admin/.arthas/lib/3.3.6/arthas...

real	0m0.572s
user	0m0.281s
sys	0m0.039s
Attach success.
telnet connecting to arthas server... current timestamp is 1594280799
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
  ,---.  ,------. ,--------.,--.  ,--.  ,---.   ,---.
 /  O  \ |  .--. ''--.  .--'|  '--'  | /  O  \ '   .-'
|  .-.  ||  '--'.'   |  |   |  .--.  ||  .-.  |`.  `-.
|  | |  ||  |\  \    |  |   |  |  |  ||  | |  |.-'    |
`--' `--'`--' '--'   `--'   `--'  `--'`--' `--'`-----'


wiki      https://arthas.aliyun.com/doc
tutorials https://arthas.aliyun.com/doc/arthas-tutorials.html
version   3.3.6
pid       58883

User data report

After the 3.1.4 version, arthas support user data report.

At startup, use the stat-url option, such as: ./as.sh --stat-url 'http://192.168.10.11:8080/api/stat'

There is a sample data report in the tunnel server that users can implement on their own.

StatController.java

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