Boost Java Debugging: Solve Production Issues in 5 Minutes with Arthas

Introduction

Debugging in production is often inefficient; Arthas can replace traditional debugging to improve daily development efficiency.

Prerequisites

Install the IDEA plugins “Arthas Idea” and “ArthasHotSwap”. The former helps generate Arthas commands, the latter enables simple hot‑deployment.

5‑Minute Problem Solving

Problem description : An interface returns a null parameter without logs, making debugging difficult.

Step 1 – Locate the method : Identify the target method and use watch to observe its parameters and return values.

Step 2 – Generate watch command : Right‑click the method name in IDEA and select “watch”. The command is copied to the clipboard.

Step 3 – Log into the remote server and run Arthas.

Step 4 – Install Arthas (one‑line install):

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

Step 5 – Start Arthas : Execute ./as.sh to enter the interactive console.

Step 6 – Execute the watch command (example):

watch com.**.**.endpoint.BargainPlayApplyCycleEndPoint fetchPlayDetailRenderData '{params,returnObj,throwExp}' -n 5 -x 3 'params[0].getPlayToolDO().getId()==588'

Explanation of the command options follows.

Step 7 – View results : The observed parameters reveal that targetId is null, leading to the root cause.

Further solution : Use ArthasHotSwap to hot‑replace the class without redeploying. After swapping, the issue is resolved and the front‑end displays correctly.

Limitations

Arthas redefine cannot change method names or fields, only the method body. Certain commands may conflict after a redefine, and ThreadLocal information can be lost during hot‑deployment.

Time Tunnel (tt) Commands

The tt command records method execution history, allowing replay, filtering, and inspection.

Record execution: tt -t List records: tt -l Search records: tt -s 'params[2].getRecordId() == 110213603' Watch a record: tt -w Replay a record: tt -p -i 1000 (or with repeat options)

Be aware that tt only stores a single object reference; changes after the call may not be reflected, which is why watch remains useful.