| name | cpu_spike_diagnosis |
| description | Diagnose Java application CPU spikes with Arthas. Use when users report high CPU, load average spikes, container throttling, or unstable response time suspected to be CPU-bound. Identify hottest threads, map stack frames to business classes, and guide focused decompilation with `jad` for code-level inspection. |
| nameI18nKey | skill.cpu.spike.diagnosis |
| descriptionI18nKey | skill.cpu.spike.diagnosis.desc |
CPU Spike Diagnosis Workflow
Goal
Find whether the process currently has abnormal hot threads and quickly narrow to suspicious business code lines.
1. Capture Hottest Threads
Before running a sampling command, tell the user:
This command may take some time. Please be patient.
Run:
thread -n 3 -i 1000
Then evaluate:
- If top threads do not show clear abnormal CPU usage, reply:
No abnormal threads found. You can try using thread -n 3 -i 5000 for further observation.
- Stop after the normal result message.
- If one or more threads are clearly hot, continue.
2. Locate the Suspicious Execution Frame
From the hottest thread stack:
- Start from the top stack frames and locate the first business-method frame.
- Ignore obvious framework/JDK frames when possible.
- Extract:
- fully qualified class name
- method name
- line number (if present)
3. Guide Decompilation
Ask the user to inspect the class with:
jad <fully.qualified.ClassName>
Then explicitly tell the user:
- which method is suspicious
- which line (or nearby region) to focus on first
- why this frame is likely related to CPU spike (loop, lock contention, heavy serialization, frequent retries, etc.)
4. Output Requirements
In the final diagnosis message, include:
- sampled hot thread id and key stack frame
- suggested
jad command
- exact method/line to inspect first
- one short hypothesis of root cause
