Arthas: what is

You think it’s like this

Actually Arthas here is shown below

In fact Arthas:

Is a command line tool
It is usually a JAR package launched through Java
A large number of bytecode and other black technology directly read and control the corresponding Java process tools

Arthas addresses major issues

From which JAR is this class loaded? Why are all kinds of class-related exceptions reported?
Why didn’t the code I changed execute? Did I not commit? Got the branch wrong?
If you encounter a problem, you cannot debug it online. Can you only re-publish it by logging?
There is a problem with a user’s data processing online, but it cannot be debugged online, and it cannot be reproduced offline!
Is there a global view of the health of the system?
Is there any way to monitor the real-time health of the JVM?
How to quickly locate application hot spots, generate flame map?

Generally speaking, it fits perfectly

Troubleshooting online/performance/offline BUG that is difficult to reproduceCopy the code

The software CPU usage is abnormally high

1. Log in to the production server 2. Copy arthas-boot.jar to the production server 3. See the big picture

dashboard
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5. Find hot threads

Thread -i 3000 - n 5Copy the code

You can also find the entry via the following script

thread 1 | grep 'main'
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6. Decompile to view the source code for further positioning,

jad --source-only com.wangji92.arthas.plugin.demo.controller.CommonController 
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7. Use monitor to count the available lines of code

monitor com.wangji92.arthas.plugin.demo.controller.CommonController add -n 10 --cycle 10
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8. Check if it is called, parameter and return value, exception

watch com.wangji92.arthas.plugin.demo.controller.CommonController * '{params,returnObj,throwExp}' -n 5 -x 3
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9. View the call chain

trace com.wangji92.arthas.plugin.demo.controller.CommonController getRandomInteger -n 10
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heapdump 1.hprof
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Mat analysis dump

The bar is high, you need to use more complex parameters or syntax sugar, and you really need a small book of commonly used syntax
Arthas is risky because it runs directly on production servers and is based on bytecodes and other technologies, bypassing security mechanisms and manipulating internal software parameters and methods, making it difficult to handle errors that are not visible from the outside
Arthas is still supposed to be a great tool for saving your sales, you don’t want to have to guess what’s wrong with the software logs in an emergency.