JVM debugging tool -arthas

Download address

link ：https://pan.baidu.com/s/1CMAR1wto-vSLIeKtlCsXJQ
Extraction code ：naza

start-up Arthas

> java -jar arthas-boot.jar --target-ip=0.0.0.0

Enter sequence number to select the process to view

1. The user executing the program needs to have the same permissions as the target process . For example admin User to execute ：sudo su admin && java -jar arthas-boot.jar or sudo -u admin -EH java -jar arthas-boot.jar.

2. If attach Not on the target process , You can see ~/logs/arthas/ Log in directory .

Browser view

Monitoring related

Perform method monitoring -monitor Class name Method

[[email protected]]> monitor com.*.*.PointerDao.SnidModel toString

Check the return value of the function -watch Class name Function name returnObj

[[email protected]]> watch com.oidd.*.Common.* encrypt returnObj

View process information -dashboard

[[email protected]]> dashboard

Method internal call path , And output the time consumption of each node on the method path -trace

Output the call path of the current method to be called -stack

Method to execute the spatiotemporal tunnel of data , Record the input and return information of each call of the specified method , And can observe these different time adjustments -tt

Generate flame chart -profiler

profiler The command supports the generation of flame diagrams of application hotspots . Essentially through continuous sampling , Then the collected sampling results are generated into a flame diagram .

profiler  The basic operation structure of the command is  profiler action [actionArg]

 Parameter description 
 Parameter name 	 Parameter description 
action	 What to do 
actionArg	 Property name pattern 
[i:]	 Sampling interval （ Company ：ns）（ The default value is ：10'000'000, namely 10 ms）
[f:]	 Dump the output to the specified path 
[d:]	 Run profiling for the specified seconds 
[e:]	 Which event to track （cpu, alloc, lock, cache-misses etc. ）, The default is cpu

start-up profiler

$ profiler start
Started [cpu] profiling

By default , The generated is cpu The flame chart of , namely event by cpu. It can be used –event Parameter to specify .

Get the collected sample The number of

$ profiler getSamples
23

see profiler state

$ profiler status
[cpu] profiling is running for 4 seconds

You can view the current profiler What kind of sample are you taking event And sampling time .

stop it profiler

Generate svg Format results

$ profiler stop
profiler output file: /tmp/demo/arthas-output/20191125-135546.svg
OK

By default , The generated results are saved in the working directory of the application arthas-output Catalog . Can pass --file Parameter to specify the output result path . such as ：

$ profiler stop --file /tmp/output.svg
profiler output file: /tmp/output.svg
OK

Generate html Format results
By default , The result file is svg Format , If you want to generate html Format , It can be used –format Parameter assignment ：

$ profiler stop --format html
profiler output file: /tmp/test/arthas-output/20191125-143329.html
OK

Or in –file The file name is used in the parameter to specify the name format . such as –file /tmp/result.html .

View... Through a browser arthas-output Below profiler result
By default ,arthas Use 3658 port , You can turn on ： http://localhost:3658/arthas-output/ Check out arthas-output Under directory profiler result

Click to see the specific results ：

If it is chrome browser , It may take several refreshes .

JVM Relevant command

Print the specified thread stack -thread Threads ID

[[email protected]]> thread 2742303

see JVM Information -jvm

[[email protected]]> jvm

see JVM environment variable -sysenv

[[email protected]]> sysenv

see JVM System attribute -sysprop

[[email protected]]> sysprop

see JVM Diagnostic configuration -vmoption

[[email protected]]> vmoption

View the current JVM Of Perf Counter Information -perfcounter

View and modify logger-logger

View the static properties of the class -getstatic

perform ognl expression -ognl

see Mbean Information about -mbean

View heap information -heapdump

Class related commands

View the loaded classes -sc wildcard

[[email protected]]> sc *

View loaded methods -sm wildcard

[[email protected]]> sm *

Decompile class —jad Class name

[[email protected]]> jad  com.*.*.Common.GlobalVariable

Memory compiler , Memory compilation .java File for .class file -mc

Load external .class file ,redefine To JVM in -redefine

dump The... Of the class has already been loaded byte code Go to a specific directory -dump

see classloader Inheritance tree of ,urls, Class loading information , Use classloader Go to getResource-classloader

Other basic commands

help—— View command help

cat—— Print file contents , and linux Inside cat Command similar

echo– Printing parameters , and linux Inside echo Command similar

grep—— Match lookup , and linux Inside grep Command similar

tee—— Copy standard input to standard output and specified file , and linux Inside tee Command similar

pwd—— Return to the current working directory , and linux Command similar

cls—— Clear the current screen area

session—— View information about the current session

reset—— Reset enhancement class , Will be Arthas All the enhanced classes are restored ,Arthas All enhanced classes will be reset when the server is shut down

version—— Output current target Java Process loaded Arthas Version number

history—— Print command history

quit—— Quit current Arthas client , other Arthas The client is not affected

stop—— close Arthas Server side , all Arthas All clients exit

keymap——Arthas List of shortcuts and custom shortcuts