Quick Start

1. Start Demo Application

Save the following code to a Demo.java and run the commands in shell as

javac Demo.java && java Demo

import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;
public class Demo {
    static class Counter {
        private static AtomicInteger count = new AtomicInteger(0);
        public static void increment() {
            count.incrementAndGet();
        
        }
        public static int value() {
            return count.get();
        
        }
    
    }

    public static void main(String[] args) throws InterruptedException {
        while (true) {
            Counter.increment();
            System.out.println("counter: " + Counter.value());
            TimeUnit.SECONDS.sleep(1);
        
        }
    
    }

}

Save the contents above into Demo.java, then compile it under the command line:

javac Demo.java
java Demo

You can also save and start the code in IDE.

2. Start Arthas

Linux/Unix/Mac

Execute the following command in the command line:

./as.sh

The user to run this script MUST have the same privilege as the owner of the target process, as a simple example you can try the following command if the target process is managed by user admin: sudo su admin && ./as.sh or sudo -u admin -EH ./as.sh. For more details on the bootstrap script, please refer to Start Arthas. If you cannot be able to attach to the target process, please check the logs under ~/logs/arthas for troubleshooting.

Select the target Java process to attach:

$ ./as.sh
Arthas script version: 3.0.2
Found existing java process, please choose one and hit RETURN.
* [1]: 95428 
  [2]: 22647 org.jetbrains.jps.cmdline.Launcher
  [3]: 21736
  [4]: 13560 Demo

The ‘Demo’ process is the fourth as shown above, press ‘4’ then ‘Enter’. Arthas will attach to the target process, and start to output:

Connecting to arthas server... current timestamp is 1536656867
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
  ,---.  ,------. ,--------.,--.  ,--.  ,---.   ,---.
 /  O  \ |  .--. ''--.  .--'|  '--'  | /  O  \ '   .-'
|  .-.  ||  '--'.'   |  |   |  .--.  ||  .-.  |`.  `-.
|  | |  ||  |\  \    |  |   |  |  |  ||  | |  |.-'    |
`--' `--'`--' '--'   `--'   `--'  `--'`--' `--'`-----'

wiki: https://alibaba.github.io/arthas
version: 3.0.1-RC-SNAPSHOT
pid: 13560
timestamp: 1536656867894

Windows

Open ‘Command’ window, execute as.bat <pid> from where the Arthas package file is unzipped.

3. Check the Dashboard

Type ‘dashboard’ and hit ‘ENTER’, a brief report on the current process will be shown as below, pls. Ctrl+C to stop:

$ 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. watch

Use ‘watch’ to check the returned value of Counter.value():

$ watch Demo$Counter value returnObj
Press Ctrl+C to abort.
Affect(class-cnt:1 , method-cnt:1) cost in 29 ms.
ts=2018-09-10 17:53:11;result=@Integer[621]
ts=2018-09-10 17:53:12;result=@Integer[622]
ts=2018-09-10 17:53:13;result=@Integer[623]
ts=2018-09-10 17:53:14;result=@Integer[624]
ts=2018-09-10 17:53:15;result=@Integer[625]

Pls. refer to advanced usages for more information.

5. Exit Arthas

Use quit or exit to disconnect from the current process. The Arthas instance attached to the target process continues to live inside the process, and its port is standby for further connection.

Use shutdown to have Arthas completely quit from the target process.