I wrote an article about how to eliminate the high cpu usage rate of linux server caused by java program - leonnew's blog - CSDN blog
The simple usage of the arthas program is mentioned in it. Let’s talk about some special features in detail today
Run a demo: wget https://arthas.aliyun.com/math-game.jar
java -jar math-game.jar
How to get arthas: wget https://arthas.aliyun.com/arthas-boot.jar
How to start: java -jar arthas-boot.jar
arthas-boot is the launcher for Arthas. It lists all the Java processes, and the user can select the target process to be diagnosed.
Select the first process, type 1 ，then type Enter：
After the Attach is successful, Arthas LOGO is printed. Enter help for more help.
Dashboard
1、The dashboard command allows you to view the real-time data panel of the current system.
Thread
2、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('.
You can see that main class is demo.MathGame:
Print the thread stack, you can see that the main class is demo.MathGame
$ thread 1 | grep 'main('
at demo.MathGame.main(MathGame.java:17)
Sc
3、The sc command can be used to find the loaded classes in the JVM:
sc -d *MathGame
Used to query the class loaded by jvm
Jad
4、The jad command can be used to decompile the byte code:
jad demo.MathGame
用来反编译代码，可以看到MathGame的main类的代码内容
--source-onlyYou can only print out the decompiled source code through parameters
jad --source-only com.example.demo.arthas.user.UserController
Watch
The watch command can view the parameter/return value/exception of the method.
watch demo.MathGame primeFactors returnObj
You can view the parameter/return value/exception information of the function.
Vmtool
The vmtool command can search object in JVM.
vmtool --action getInstances --className java.lang.String --limit 10
bash $ vmtool --action getInstances --className java.lang.String --limit 10 @String[][ @String[com/taobao/arthas/core/shell/session/Session], @String[com.taobao.arthas.core.shell.session.Session], @String[com/taobao/arthas/core/shell/session/Session], @String[com/taobao/arthas/core/shell/session/Session], @String[com/taobao/arthas/core/shell/session/Session.class], @String[com/taobao/arthas/core/shell/session/Session.class], @String[com/taobao/arthas/core/shell/session/Session.class], @String[com/], @String[java/util/concurrent/ConcurrentHashMap$ValueIterator], @String[java/util/concurrent/locks/LockSupport], ]
You can see the running mechanism of the jvm virtual machine
Arthas can be exited with the exit or quit command.
exit and quit can exit arthas