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Java 诊断工具 Arthas 基础教程
本博文来源于学习阿里云知行动手实验室笔记，传送门
写在前面，博主从17年接触到Java，开启半年自学入行，博客名为逆流者blog，希望一直可以保持乐观、积极的学习心态，在编程的世界里逆流而上。
Arthas 基础教程
Arthas 是Alibaba开源的Java诊断工具，深受开发者喜爱。在线排查问题，无需重启；动态跟踪Java代码；实时监控JVM状态。
Arthas 支持JDK 6+，支持Linux/Mac/Windows，采用命令行交互模式，同时提供丰富的 Tab 自动补全功能，进一步方便进行问题的定位和诊断。
Github: https://github.com/alibaba/arthas
文档: https://arthas.aliyun.com/doc/启动arthas-demo
下载arthas-demo.jar，再用java -jar命令启动：
wget https://arthas.aliyun.com/arthas-demo.jar;java -jar arthas-demo.jar- 1
arthas-demo是一个很简单的程序，它随机生成整数，再执行因式分解，把结果打印出来。如果生成的随机数是负数，则会打印提示信息。
比如一些打印提示信息：
--2022-07-28 11:39:12-- https://arthas.aliyun.com/arthas-demo.jar Resolving arthas.aliyun.com (arthas.aliyun.com)... 203.119.207.129 Connecting to arthas.aliyun.com (arthas.aliyun.com)|203.119.207.129|:443... connected. HTTP request sent, awaiting response... 200 OK Length: 4499 (4.4K) [application/java-archive] Saving to: ‘arthas-demo.jar’ arthas-demo.jar 100%[==========>] 4.39K --.-KB/s in 0s 2022-07-28 11:39:12 (44.0 MB/s) - ‘arthas-demo.jar’ saved [4499/4499] 111330=2*3*3*5*1237 151728=2*2*2*2*3*29*109 illegalArgumentCount: 1, number is: -46721, need >= 2 19857=3*6619 93218=2*127*367 165986=2*149*557 illegalArgumentCount: 2, number is: -164359, need >= 2 illegalArgumentCount: 3, number is: -210982, need >= 2 211310=2*5*11*17*113 54104=2*2*2*6763- 1
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启动arthas-boot
在新的Terminal 2里，下载arthas-boot.jar，再用java -jar命令启动：
wget https://arthas.aliyun.com/arthas-boot.jar;java -jar arthas-boot.jar- 1
arthas-boot是Arthas的启动程序，它启动后，会列出所有的Java进程，用户可以选择需要诊断的目标进程。
Requesting a Cloud Shell.Succeeded. Connecting terminal Welcome to Alibaba Cloud Shell! Type "help" to learn about Cloud Shell Type "aliyun" to use Alibaba Cloud CLI shell@Alicloud:~$ wget https://arthas.aliyun.com/arthas-boot.jar;java -jar arthas-boot.jar --2022-07-28 11:49:44-- https://arthas.aliyun.com/arthas-boot.jar Resolving arthas.aliyun.com (arthas.aliyun.com)... 203.119.207.243 Connecting to arthas.aliyun.com (arthas.aliyun.com)|203.119.207.243|:443... connected. HTTP request sent, awaiting response... 200 OK Length: 141872 (139K) [application/java-archive] Saving to: ‘arthas-boot.jar’ arthas-boot.jar 100%[====================================================>] 138.55K 343KB/s in 0.4s 2022-07-28 11:49:46 (343 KB/s) - ‘arthas-boot.jar’ saved [141872/141872] [INFO] arthas-boot version: 3.6.3 [INFO] Found existing java process, please choose one and input the serial number of the process, eg : 1. Then hit ENTER. * [1]: 1265 arthas-demo.jar- 1
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选择第一个进程，输入 1 ，再Enter/回车：
1- 1
Attach成功之后，会打印Arthas LOGO。
[INFO] Start download arthas from remote server: https://arthas.aliyun.com/download/3.6.2?mirror=aliyun [INFO] Download arthas success. [INFO] arthas home: /home/shell/.arthas/lib/3.6.2/arthas [INFO] Try to attach process 1265 [INFO] Attach process 1265 success. [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 3.6.2 main_class pid 1265 time 2022-07-28 11:50:39 [arthas@1265]$- 1
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输入 help 可以获取到更多的帮助信息。
help- 1
显示了可以在
[arthas@1265]$中的命令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 count, 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 exception of specified method invocation tt Time Tunnel jvm Display the target JVM information memory Display jvm memory info. perfcounter Display the perf counter information. ognl Execute ognl expression. mc Memory compiler, compiles java files into bytecode and class files in memory. redefine Redefine classes. @see Instrumentation#redefineClasses(ClassDefinition...) retransform Retransform classes. @see Instrumentation#retransformClasses(Class...) 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-profiler vmtool jvm tool stop Stop/Shutdown Arthas server and exit the console.- 1
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Dashboard
dashboard 命令可以查看当前系统的实时数据面板。
dashboard- 1
ID NAME GROUP PRIORITY STATE %CPU DELTA_TIME TIME INTERRUPTE DAEMON -1 C1 CompilerThread1 - -1 - 0.17 0.008 0:0.453 false true 22 Timer-for-arthas-dashboard-259 system 5 RUNNABLE 0.17 0.008 0:0.040 false true 20 arthas-NettyHttpTelnetBootstra system 5 RUNNABLE 0.09 0.004 0:0.097 false true -1 VM Periodic Task Thread - -1 - 0.08 0.003 0:0.390 false true 1 main main 5 TIMED_WAI 0.02 0.001 0:0.189 false false -1 C2 CompilerThread0 - -1 - 0.02 0.000 0:0.551 false true -1 VM Thread - -1 - 0.01 0.000 0:0.105 false true 16 arthas-shell-server system 9 TIMED_WAI 0.0 0.000 0:0.002 false true 17 arthas-session-manager system 9 TIMED_WAI 0.0 0.000 0:0.000 false true 2 Reference Handler system 10 WAITING 0.0 0.000 0:0.001 false true 3 Finalizer system 8 WAITING 0.0 0.000 0:0.002 false true 4 Signal Dispatcher system 9 RUNNABLE 0.0 0.000 0:0.000 false true 8 Attach Listener system 9 RUNNABLE 0.0 0.000 0:0.025 false true 10 arthas-timer system 9 WAITING 0.0 0.000 0:0.000 false true 13 arthas-NettyHttpTelnetBootstra system 5 RUNNABLE 0.0 0.000 0:0.025 false true 14 arthas-NettyWebsocketTtyBootst system 5 RUNNABLE 0.0 0.000 0:0.001 false true 15 arthas-NettyWebsocketTtyBootst system 5 RUNNABLE 0.0 0.000 0:0.001 false true 18 arthas-UserStat system 9 WAITING 0.0 0.000 0:0.000 false true 21 arthas-command-execute system 5 TIMED_WAI 0.0 0.000 0:0.017 false true -1 Service Thread - -1 - 0.0 0.000 0:0.000 false true Memory used total max usage GC heap 19M 42M 444M 4.32% gc.copy.count 8 eden_space 1M 11M 122M 1.35% gc.copy.time(ms) 48 survivor_space 0K 1472K 15680K 0.00% gc.marksweepcompact.count 1 tenured_gen 17M 29M 306M 5.72% gc.marksweepcompact.time(ms) 27 nonheap 27M 28M -1 96.78% code_cache 4M 4M 240M 1.97% metaspace 20M 21M -1 96.58% compressed_class_space 2M 2M 1024M 0.25% direct 8K 8K - 100.01% mapped 0K 0K - 0.00% Runtime os.name Linux os.version 3.10.0-957.21.3.el7.x86_64 java.version 1.8.0_292 java.home /usr/lib/jvm/java-8-openjdk-amd64/jre systemload.average 0.00 processors 1 timestamp/uptime Thu Jul 28 11:57:43 CST 2022/483s- 1
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输入 q 或者 Ctrl+C 可以退出dashboard命令。
Thread
thread 1 命令会打印线程ID 1的栈。
thread 1- 1
"main" Id=1 TIMED_WAITING at java.lang.Thread.sleep(Native Method) at java.lang.Thread.sleep(Thread.java:340) at java.util.concurrent.TimeUnit.sleep(TimeUnit.java:386) at demo.MathGame.main(MathGame.java:17)- 1
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Arthas支持管道，可以用 thread 1 | grep ‘main(’ 查找到main class。
thread 1 | grep 'main('- 1
可以直接找到main(这一行
at demo.MathGame.main(MathGame.java:17)- 1
这样可以看到main class是demo.MathGame 17这一行
Sc
可以通过 sc 命令来查找JVM里已加载的类：
sc -d *MathGame- 1
查到 demo.MathGame 类的信息
class-info demo.MathGame code-source /home/shell/arthas-demo.jar name demo.MathGame isInterface false isAnnotation false isEnum false isAnonymousClass false isArray false isLocalClass false isMemberClass false isPrimitive false isSynthetic false simple-name MathGame modifier public annotation interfaces super-class +-java.lang.Object class-loader +-sun.misc.Launcher$AppClassLoader@1b6d3586 +-sun.misc.Launcher$ExtClassLoader@4680ef6b classLoaderHash 1b6d3586 Affect(row-cnt:1) cost in 44 ms.- 1
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Jad
可以通过 jad 命令来反编译代码：
jad demo.MathGame- 1
ClassLoader: +-sun.misc.Launcher$AppClassLoader@1b6d3586 +-sun.misc.Launcher$ExtClassLoader@4680ef6b Location: /home/shell/arthas-demo.jar /* * Decompiled with CFR. */ package demo; import java.util.ArrayList; import java.util.List; import java.util.Random; import java.util.concurrent.TimeUnit; public class MathGame { private static Random random = new Random(); public int illegalArgumentCount = 0; public ListprimeFactors(int number) { /*44*/ if (number < 2) { /*45*/ ++this.illegalArgumentCount; throw new IllegalArgumentException("number is: " + number + ", need >= 2"); } ArrayList result = new ArrayList (); /*50*/ int i = 2; /*51*/ while (i <= number) { /*52*/ if (number % i == 0) { /*53*/ result.add(i); /*54*/ number /= i; /*55*/ i = 2; continue; } /*57*/ ++i; } /*61*/ return result; } public static void main(String[] args) throws InterruptedException { MathGame game = new MathGame(); while (true) { /*16*/ game.run(); /*17*/ TimeUnit.SECONDS.sleep(1L); } } public void run() throws InterruptedException { try { /*23*/ int number = random.nextInt() / 10000; /*24*/ List primeFactors = this.primeFactors(number); /*25*/ MathGame.print(number, primeFactors); } catch (Exception e) { /*28*/ System.out.println(String.format("illegalArgumentCount:%3d, ", this.illegalArgumentCount) + e.getMessage()); } } public static void print(int number, List primeFactors) { StringBuffer sb = new StringBuffer(number + "="); /*34*/ for (int factor : primeFactors) { /*35*/ sb.append(factor).append('*'); } /*37*/ if (sb.charAt(sb.length() - 1) == '*') { /*38*/ sb.deleteCharAt(sb.length() - 1); } /*40*/ System.out.println(sb); } } Affect(row-cnt:1) cost in 1233 ms. - 1
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Watch
通过watch命令可以查看函数的参数/返回值/异常信息。
查看demo.MathGame类 primeFactors方法的返回值：
watch demo.MathGame primeFactors returnObj- 1
Press Q or Ctrl+C to abort. Affect(class count: 1 , method count: 1) cost in 245 ms, listenerId: 1 method=demo.MathGame.primeFactors location=AtExceptionExit ts=2022-07-28 14:34:00; [cost=0.899344ms] result=null method=demo.MathGame.primeFactors location=AtExit ts=2022-07-28 14:34:01; [cost=0.913815ms] result=@ArrayList[ @Integer[2], @Integer[52433], ] method=demo.MathGame.primeFactors location=AtExceptionExit ts=2022-07-28 14:34:02; [cost=0.065352ms] result=null method=demo.MathGame.primeFactors location=AtExceptionExit ts=2022-07-28 14:34:03; [cost=0.040286ms] result=null method=demo.MathGame.primeFactors location=AtExit ts=2022-07-28 14:34:04; [cost=0.435046ms] result=@ArrayList[ @Integer[2], @Integer[25439], ]- 1
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输入 q 或者 Ctrl+C 退出watch命令。
Exit/Stop
退出Arthas
用 exit 或者 quit 命令可以退出Arthas。
exit- 1
退出Arthas之后，还可以再次用 java -jar arthas-boot.jar 来连接。
java -jar arthas-boot.jar- 1
彻底退出Arthas
exit/quit命令只是退出当前session，arthas server还在目标进程中运行。
想完全退出Arthas，可以执行 stop 命令。
stop- 1
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- 原文地址：https://blog.csdn.net/weixin_45847167/article/details/126002797
