使用arthas排查 test 问题

1. 启动math-game

	curl -O https://arthas.aliyun.com/math-game.jar
	java -jar math-game.jar

math-game是一个简单的程序，每隔一秒生成一个随机数，再执行质因数分解，并打印出分解结果。

math-game源代码：查看

2. 启动arthas

在命令行下面执行（使用和目标进程一致的用户启动，否则可能attach失败）：

	curl -O https://arthas.aliyun.com/arthas-boot.jar
	java -jar arthas-boot.jar

• 执行该程序的用户需要和目标进程具有相同的权限。比如以admin用户来执行：sudo su admin && java -jar arthas-boot.jar 或 sudo -u admin -EH java -jar arthas-boot.jar。

• 如果attach不上目标进程，可以查看~/logs/arthas/ 目录下的日志。

• 如果下载速度比较慢，可以使用aliyun的镜像：java -jar arthas-boot.jar --repo-mirror aliyun --use-http

• java -jar arthas-boot.jar -h 打印更多参数信息。

选择应用java进程：

	$ $ java -jar arthas-boot.jar
	* [1]: 35542
	[2]: 71560 math-game.jar

math-game进程是第2个，则输入2，再输入回车/enter。Arthas会attach到目标进程上，并输出日志：

	[INFO] Try to attach process 71560
	[INFO] Attach process 71560 success.
	[INFO] arthas-client connect 127.0.0.1 3658
	,---. ,------. ,--------.,--. ,--. ,---. ,---.
	/ O | .--. ''--. .--'| '--' | / O ' .-'
	| .-. || '--'.' | | | .--. || .-. |`. `-.
	| | | || | | | | | | || | | |.-' |
	`--' `--'`--' '--' `--' `--' `--'`--' `--'`-----'
	wiki: https://arthas.aliyun.com/doc
	version: 3.0.5.20181127201536
	pid: 71560
	time: 2018-11-28 19:16:24
	$

3. 查看dashboard

输入dashboard，按回车/enter，会展示当前进程的信息，按ctrl+c可以中断执行。

	$ dashboard
	ID NAME GROUP PRIORI STATE %CPU TIME INTERRU DAEMON
	17 pool-2-thread-1 system 5 WAITIN 67 0:0 false false
	27 Timer-for-arthas-dashb system 10 RUNNAB 32 0:0 false true
	11 AsyncAppender-Worker-a system 9 WAITIN 0 0:0 false true
	9 Attach Listener system 9 RUNNAB 0 0:0 false true
	3 Finalizer system 8 WAITIN 0 0:0 false true
	2 Reference Handler system 10 WAITIN 0 0:0 false true
	4 Signal Dispatcher system 9 RUNNAB 0 0:0 false true
	26 as-command-execute-dae system 10 TIMED_ 0 0:0 false true
	13 job-timeout system 9 TIMED_ 0 0:0 false true
	1 main main 5 TIMED_ 0 0:0 false false
	14 nioEventLoopGroup-2-1 system 10 RUNNAB 0 0:0 false false
	18 nioEventLoopGroup-2-2 system 10 RUNNAB 0 0:0 false false
	23 nioEventLoopGroup-2-3 system 10 RUNNAB 0 0:0 false false
	15 nioEventLoopGroup-3-1 system 10 RUNNAB 0 0:0 false false
	Memory used total max usage GC
	heap 32M 155M 1820M 1.77% gc.ps_scavenge.count 4
	ps_eden_space 14M 65M 672M 2.21% gc.ps_scavenge.time(m 166
	ps_survivor_space 4M 5M 5M s)
	ps_old_gen 12M 85M 1365M 0.91% gc.ps_marksweep.count 0
	nonheap 20M 23M -1 gc.ps_marksweep.time( 0
	code_cache 3M 5M 240M 1.32% ms)
	Runtime
	os.name Mac OS X
	os.version 10.13.4
	java.version 1.8.0_162
	java.home /Library/Java/JavaVir
	tualMachines/jdk1.8.0
	_162.jdk/Contents/Hom
	e/jre

4. 通过thread命令来获取到math-game进程的Main Class

thread 1会打印线程ID 1的栈，通常是main函数的线程。

	$ thread 1 | grep 'main('
	at demo.MathGame.main(MathGame.java:17)

5. 通过jad来反编译Main Class

	$ jad demo.MathGame
	ClassLoader:
	+-sun.misc.Launcher$AppClassLoader@3d4eac69
	+-sun.misc.Launcher$ExtClassLoader@66350f69
	Location:
	/tmp/math-game.jar
	/*
	* Decompiled with CFR 0_132.
	*/
	package demo;
	import java.io.PrintStream;
	import java.util.ArrayList;
	import java.util.Iterator;
	import java.util.List;
	import java.util.Random;
	import java.util.concurrent.TimeUnit;
	public class MathGame {
	private static Random random = new Random();
	private int illegalArgumentCount = 0;
	public static void main(String[] args) throws InterruptedException {
	MathGame game = new MathGame();
	do {
	game.run();
	TimeUnit.SECONDS.sleep(1L);
	} while (true);
	}
	public void run() throws InterruptedException {
	try {
	int number = random.nextInt();
	List<Integer> primeFactors = this.primeFactors(number);
	MathGame.print(number, primeFactors);
	}
	catch (Exception e) {
	System.out.println(String.format("illegalArgumentCount:%3d, ", this.illegalArgumentCount) + e.getMessage());
	}
	}
	public static void print(int number, List<Integer> primeFactors) {
	StringBuffer sb = new StringBuffer("" + number + "=");
	Iterator<Integer> iterator = primeFactors.iterator();
	while (iterator.hasNext()) {
	int factor = iterator.next();
	sb.append(factor).append('*');
	}
	if (sb.charAt(sb.length() - 1) == '*') {
	sb.deleteCharAt(sb.length() - 1);
	}
	System.out.println(sb);
	}
	public List<Integer> primeFactors(int number) {
	if (number < 2) {
	++this.illegalArgumentCount;
	throw new IllegalArgumentException("number is: " + number + ", need >= 2");
	}
	ArrayList<Integer> result = new ArrayList<Integer>();
	int i = 2;
	while (i <= number) {
	if (number % i == 0) {
	result.add(i);
	number /= i;
	i = 2;
	continue;
	}
	++i;
	}
	return result;
	}
	}
	Affect(row-cnt:1) cost in 970 ms.

6. watch

通过watch命令来查看demo.MathGame#primeFactors函数的返回值：

	$ watch demo.MathGame primeFactors returnObj
	Press Ctrl+C to abort.
	Affect(class-cnt:1 , method-cnt:1) cost in 107 ms.
	ts=2018-11-28 19:22:30; [cost=1.715367ms] result=null
	ts=2018-11-28 19:22:31; [cost=0.185203ms] result=null
	ts=2018-11-28 19:22:32; [cost=19.012416ms] result=@ArrayList[
	@Integer[5],
	@Integer[47],
	@Integer[2675531],
	]
	ts=2018-11-28 19:22:33; [cost=0.311395ms] result=@ArrayList[
	@Integer[2],
	@Integer[5],
	@Integer[317],
	@Integer[503],
	@Integer[887],
	]
	ts=2018-11-28 19:22:34; [cost=10.136007ms] result=@ArrayList[
	@Integer[2],
	@Integer[2],
	@Integer[3],
	@Integer[3],
	@Integer[31],
	@Integer[717593],
	]
	ts=2018-11-28 19:22:35; [cost=29.969732ms] result=@ArrayList[
	@Integer[5],
	@Integer[29],
	@Integer[7651739],
	]

更多的功能可以查看进阶使用。

7. 退出arthas

如果只是退出当前的连接，可以用quit或者exit命令。Attach到目标进程上的arthas还会继续运行，端口会保持开放，下次连接时可以直接连接上。

如果想完全退出arthas，可以执行stop命令。

 

https://arthas.aliyun.com/doc/quick-start.html