Arthas is a Java diagnostic tool open source by Alibaba in September 2018. It supports JDK6 + and adopts command-line interaction mode, which can easily locate and diagnose online program operation problems. The official document of Arthas is very detailed. See: https://alibaba.github.io/arthas
Arthas usage scenario
Thanks to the powerful and rich functions of Arthas, what Arthas can do is beyond imagination. Just a few common usage cases are listed below. More usage scenarios can be explored by yourself after you are familiar with Arthas.
Is there a global perspective to view the health of the system?
Why does the CPU rise again? Where does it occupy the CPU?
Is there a deadlock in the running multithread? Is there a blockage?
The program takes a long time to run. Where does it take a long time? How to monitor?
Which jar package is this class loaded from? Why do you report all kinds of related exceptions?
Why didn't the code I changed execute? Am I not commit ted? Wrong branch?
You can't debug online when you encounter problems. Can you only republish it by adding logs?
Is there any way to monitor the real-time running status of the JVM?
1, Download Arthas boot jar
There are two official ways to download Arthas boot Jar or directly install and use as sh. The former is explained here. I download the jar package
curl -O https://alibaba.github.io/arthas/arthas-boot.jar
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 138k 100 138k 0 0 177k 0 --:--:-- --:--:-- --:--:-- 176k
2, Run Arthas boot jar
The whole arthas is developed in java language, so it can be run directly in java jar
$ java -jar arthas-boot.jar [INFO] arthas-boot version: 3.5.3 [INFO] Process 67746 already using port 3658 [INFO] Process 67746 already using port 8563 [INFO] Found existing java process, please choose one and input the serial number of the process, eg : 1. Then hit ENTER. * [1]: 67746 springboot-mybatis-all-1.0.0.jar [2]: 70997 com.huohuo.service.jvm.DeadLockTest [3]: 70996 org.jetbrains.jps.cmdline.Launcher [4]: 70570 [5]: 70798 org.jetbrains.idea.maven.server.RemoteMavenServer36 1 [INFO] arthas home: /Users/huoyajing/.arthas/lib/3.5.5/arthas [INFO] The target process already listen port 3658, skip attach. [INFO] arthas-client connect 127.0.0.1 3658 ,---. ,------. ,--------.,--. ,--. ,---. ,---. / O \ | .--. ''--. .--'| '--' | / O \ ' .-' | .-. || '--'.' | | | .--. || .-. |`. `-. | | | || |\ \ | | | | | || | | |.-' | `--' `--'`--' '--' `--' `--' `--'`--' `--'`-----' wiki https://arthas.aliyun.com/doc tutorials https://arthas.aliyun.com/doc/arthas-tutorials.html version 3.5.5 main_class org.springframework.boot.loader.JarLauncher pid 67746 time 2022-03-02 15:43:29 [arthas@67746]$
1) Select the jps process to monitor
You can also directly Java - jar Arthas boot Jar PID directly into the topic.
Note:[ arthas@67746 ]$indicates that you have opened the monitoring client, where you can execute relevant commands for viewing. You can use quit (exit the current client), stop\shutdown (close the Arthas server and exit all clients).
67746 is PID.
2) Visual interface operation http://127.0.0.1:8563/
In addition to viewing on the command line, it can also be accessed through the browser http://127.0.0.1:8563/ see. As shown in the following figure: you can directly operate the relevant command parameters
3, Common commands
1)help
[arthas@73120]$ help
NAME DESCRIPTION
help Display Arthas Help
auth Authenticates the current session
keymap Display all the available keymap for the specified connection.
sc Search all the classes loaded by JVM
sm Search the method of classes loaded by JVM
classloader Show classloader info
jad Decompile class
getstatic Show the static field of a class
monitor Monitor method execution statistics, e.g. total/success/failure c
ount, average rt, fail rate, etc.
stack Display the stack trace for the specified class and method
thread Display thread info, thread stack
trace Trace the execution time of specified method invocation.
watch Display the input/output parameter, return object, and thrown exc
eption of specified method invocation
tt Time Tunnel
jvm Display the target JVM information
perfcounter Display the perf counter information.
ognl Execute ognl expression.
mc Memory compiler, compiles java files into bytecode and class file
s in memory.
redefine Redefine classes. @see Instrumentation#redefineClasses(ClassDefin
ition...)
retransform Retransform classes. @see Instrumentation#retransformClasses(Clas
s...)
dashboard Overview of target jvm's thread, memory, gc, vm, tomcat info.
dump Dump class byte array from JVM
heapdump Heap dump
options View and change various Arthas options
cls Clear the screen
reset Reset all the enhanced classes
version Display Arthas version
session Display current session information
sysprop Display, and change the system properties.
sysenv Display the system env.
vmoption Display, and update the vm diagnostic options.
logger Print logger info, and update the logger level
history Display command history
cat Concatenate and print files
base64 Encode and decode using Base64 representation
echo write arguments to the standard output
pwd Return working directory name
mbean Display the mbean information
grep grep command for pipes.
tee tee command for pipes.
profiler Async Profiler. https://github.com/jvm-profiling-tools/async-prof
iler
vmtool jvm tool
stop Stop/Shutdown Arthas server and exit the console.
2) dashboard can view the running status of the whole process, including thread, memory, GC and running environment information
It mainly shows three parts: thread, jvm and Java env. It will refresh automatically every few seconds
3) Thread thread information
In fact, it is the first part of the result obtained by dashboard
thread -n num view the results of the first three threads and sort them according to CPU usage
[arthas@16645]$ thread -n 3
"Thread-0" Id=10 cpuUsage=99.16% deltaTime=199ms time=53423ms RUNNABLE
at com.huohuo.service.jvm.ArthasTest.lambda$cpuHigh$1(ArthasTest.java:47)
at com.huohuo.service.jvm.ArthasTest$$Lambda$1/1407343478.run(Unknown Source)
at java.lang.Thread.run(Thread.java:748)
"arthas-command-execute" Id=28 cpuUsage=0.16% deltaTime=0ms time=18ms RUNNABLE
at sun.management.ThreadImpl.dumpThreads0(Native Method)
at sun.management.ThreadImpl.getThreadInfo(ThreadImpl.java:448)
at com.taobao.arthas.core.command.monitor200.ThreadCommand.processTopBusyThreads(ThreadCommand.java:206)
at com.taobao.arthas.core.command.monitor200.ThreadCommand.process(ThreadCommand.java:122)
at com.taobao.arthas.core.shell.command.impl.AnnotatedCommandImpl.process(AnnotatedCommandImpl.java:82)
at com.taobao.arthas.core.shell.command.impl.AnnotatedCommandImpl.access$100(AnnotatedCommandImpl.java:18)
at com.taobao.arthas.core.shell.command.impl.AnnotatedCommandImpl$ProcessHandler.handle(AnnotatedCommandImpl.java:111)
at com.taobao.arthas.core.shell.command.impl.AnnotatedCommandImpl$ProcessHandler.handle(AnnotatedCommandImpl.java:108)
at com.taobao.arthas.core.shell.system.impl.ProcessImpl$CommandProcessTask.run(ProcessImpl.java:385)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:748)
"C1 CompilerThread2" [Internal] cpuUsage=0.13% deltaTime=0ms time=462ms
4) thread pid view the specific result of a thread
5) thread -b deadlock information without pid
[arthas@3987]$ thread -b
"Thread-1" Id=11 BLOCKED on java.lang.Object@57d20628 owned by "Thread-2" Id=12
at com.huohuo.service.jvm.ArthasTest.lambda$deadThread$2(ArthasTest.java:68)
- blocked on java.lang.Object@57d20628
- locked java.lang.Object@7bd50b57 <---- but blocks 1 other threads!
at com.huohuo.service.jvm.ArthasTest$$Lambda$2/2121744517.run(Unknown Source)
at java.lang.Thread.run(Thread.java:748)
```bash
[arthas@3987]$ thread 10
"Thread-0" Id=10 RUNNABLE
at com.huohuo.service.jvm.ArthasTest.lambda$cpuHigh$1(ArthasTest.java:44)
at com.huohuo.service.jvm.ArthasTest$$Lambda$1/1407343478.run(Unknown Source)
at java.lang.Thread.run(Thread.java:748)
We can clearly see the problem arthastest Java: there is a problem with line 44.
6) Full path decompilation of jad class
This makes it easy for us to check whether the online code is the correct version.
[arthas@3987]$ jad com.huohuo.service.jvm.ArthasTest
//These are the class loading mechanisms AppClassLoader (application class loader) and ExtClassLoader (extension class loader)
ClassLoader:
+-sun.misc.Launcher$AppClassLoader@18b4aac2
+-sun.misc.Launcher$ExtClassLoader@7da3e221
//My project path
Location:
/Users/huoyajing/information/spring/springBoot/J2020/springboot-mybatis-all/target/classes/
//The following information is clear. It's very convenient to check whether the online code is the latest. It's very convenient
/*
* Decompiled with CFR.
*/
package com.huohuo.service.jvm;
import java.util.HashSet;
public class ArthasTest {
private static HashSet hashSet = new HashSet();
public static void cpuHigh() {
new Thread(() -> {
while (true) {
// Infinite loop
}
}).start();
}
public static void addHashSetThread() {
new Thread(() -> {
/*29*/ int count = 0;
while (true) {
try {
while (true) {
/*32*/ hashSet.ad
......ellipsis
7) ognl can view / modify the values on the system line
ognl '@ full path category @ static attribute name' calls static attribute
[arthas@11021]$ ognl @com.huohuo.service.jvm.ArthasTest@hashSet
@HashSet[
@String[count1],
@String[count2],
@String[count0],
@String[count27],
@String[count5],
@String[count26],
@String[count6],
@String[count25],
@String[count3],
@String[count24],
@String[count4],
@String[count23],
@String[count9],
@String[count7],
@String[count8],
@String[count22],
@String[count21],
@String[count20],
@String[count19],
@String[count18],
@String[count17],
@String[count16],
@String[count15],
@String[count14],
@String[count13],
@String[count12],
@String[count11],
@String[count10],
]
[arthas@11021]$ ognl @com.huohuo.service.jvm.ArthasTest@integer @Integer[2]
ognl '@ full path category @ static method name ("parameter")' call static method
ognl '@com.huohuo.service.jvm.ArthasTest@hashSet.add("huohuo")'
...
8) sc -d full path class information
[arthas@16645]$ sc -d com.huohuo.service.jvm.ArthasTest
class-info com.huohuo.service.jvm.ArthasTest
code-source /Users/huoyajing/information/spring/springBoot/J2020/springbo
ot-mybatis-all/target/classes/
name com.huohuo.service.jvm.ArthasTest
isInterface false
isAnnotation false
isEnum false
isAnonymousClass false
isArray false
isLocalClass false
isMemberClass false
isPrimitive false
isSynthetic false
simple-name ArthasTest
modifier public
annotation
interfaces
super-class +-java.lang.Object
class-loader +-sun.misc.Launcher$AppClassLoader@18b4aac2
+-sun.misc.Launcher$ExtClassLoader@7da3e221
classLoaderHash 18b4aac2
Affect(row-cnt:1) cost in 33 ms.
4, [ERROR] attach fail, targetPid: 77710
I started the java process directly from idea and run.
$ java -jar arthas-boot.jar [INFO] arthas-boot version: 3.5.1 [INFO] Found existing java process, please choose one and input the serial number of the process, eg : 1. Then hit ENTER. * [1]: 70570 [2]: 77709 org.jetbrains.jps.cmdline.Launcher [3]: 77710 com.huohuo.service.jvm.ArthasTest 3 [INFO] arthas home: /Users/huoyajing/.arthas/lib/3.5.5/arthas [INFO] Try to attach process 77710 [WARN] Current VM java version: 13 do not match target VM java version: 1.8, attach may fail. [WARN] Target VM JAVA_HOME is /Library/Java/JavaVirtualMachines/jdk1.8.0_131.jdk/Contents/Home/jre, arthas-boot JAVA_HOME is /Library/Java/JavaVirtualMachines/jdk-13.0.2.jdk/Contents/Home, try to set the same JAVA_HOME. [ERROR] Start arthas failed, exception stack trace: com.sun.tools.attach.AgentLoadException: 0 at jdk.attach/sun.tools.attach.HotSpotVirtualMachine.loadAgentLibrary(HotSpotVirtualMachine.java:108) at jdk.attach/sun.tools.attach.HotSpotVirtualMachine.loadAgentLibrary(HotSpotVirtualMachine.java:119) at jdk.attach/sun.tools.attach.HotSpotVirtualMachine.loadAgent(HotSpotVirtualMachine.java:147) at com.taobao.arthas.core.Arthas.attachAgent(Arthas.java:122) at com.taobao.arthas.core.Arthas.<init>(Arthas.java:27) at com.taobao.arthas.core.Arthas.main(Arthas.java:151) [ERROR] attach fail, targetPid: 77710
$ java -version java version "13.0.2" 2020-01-14 Java(TM) SE Runtime Environment (build 13.0.2+8) Java HotSpot(TM) 64-Bit Server VM (build 13.0.2+8, mixed mode, sharing)
Then I switched the JDK version to JDK8. It's really no problem. Why is this problem? Because my Idea is executed using JDK8. iTerm started with JDK13, so the version is different. Change it to solve the problem.