Mastering Arthas: Practical Guide to Java Process Debugging and Monitoring

Installation

Run the one‑line installer to get Arthas ready:

curl -L https://arthas.aliyun.com/install.sh | sh

After installation, the as.sh script provides the main interface.

Selecting a Java Process

Execute ./as.sh to list running Java processes and choose one by its serial number, or directly specify the PID:

./as.sh               # interactive selection
./as.sh 19408        # attach to process 19408

The console will display the selected process information and attach to the target JVM.

Session Command

Shows current session details, such as the Java PID and session ID:

[arthas@19408]$ session
Name        Value
--------------------------
JAVA_PID    19408
SESSION_ID  37832025-711c-45f8-880e-114aa51c5dcc

Exit / Quit Commands

Terminate the current Arthas client without stopping the server:

[arthas@19408]$ quit
Connection closed by foreign host.

Re‑attach later; the server remains running.

Dashboard Command

Displays a real‑time panel of thread and memory metrics. Example excerpt:

[arthas@19408]$ dashboard
ID   NAME                     STATE   %CPU   TIME
77   SimplePauseDetectorThread_0  TIMED_WAIT 0.0   80:04.758
...

Key sections include thread list, memory usage, GC statistics, and runtime information.

Thread Command

Lists all threads with detailed attributes (ID, name, group, priority, state, CPU%, etc.) and supports filters such as most busy threads or blocking threads:

[arthas@19408]$ thread -n 3
"arthas-command-execute" Id=164 cpuUsage=0.85% ...

JVM Command

Provides JVM configuration and runtime details, including version, class‑loading stats, compilation time, garbage‑collector counts, memory managers, and thread counts.

[arthas@19408]$ jvm
RUNTIME
--------------------------------
MACHINE-NAME 19408@host-192-168-65-23
JVM-START-TIME 2022-01-24 11:32:18
...

Trace Command (use with caution in production)

Shows the call chain of a specific method and the time spent at each node:

[arthas@19625]$ trace com.pilot.basic.system.controller.SysUserManageController saveUser
---[134.78ms] com.pilot...SysUserManageController$$Enhancer...saveUser()
    +---[108.34ms] com.pilot...BaseParam:getCurrSystemPkId()
    ...
    `---throw: BusinessException [不允许添加超级管理员。]

Monitor Command (use with caution in production)

Monitors method execution statistics such as total calls, successes, failures, average response time, and failure rate:

[arthas@19625]$ monitor com.pilot.basic.system.controller.SysUserManageController saveUser -c 2
timestamp               class                                 method   total success fail avg-rt(ms) fail-rate
2022-02-26 23:35:06     com.pilot...SysUserManageController   saveUser 1     0       1   47.04      100.00%

Key Tips

Check DEADLOCK-COUNT (zero indicates no deadlocks).

Focus on success count, average response time, and failure rate when using trace or monitor.

For the next article, the author promises to continue using Arthas for online issue tracing and tracking.