How do I install the Jstack skill?

Run npx skillmds@latest add majiayu000/jstack in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

Is Jstack safe to use?

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Which AI agents work with Jstack?

This skill is tagged as working with Claude Code, Claude.ai, OpenAI Codex. SKILL.md is an open format, so most agents that read a skills directory can load it too.

Is Jstack free to use?

Yes. Installing skills from SkillMD is free, and the skill stays under its author's original license.

Who published Jstack?

majiayu000 (@majiayu000) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Jstack by majiayu000 — Agent Skill

Name: Jstack
Rating: 4.5 (4 reviews)
Author: majiayu000

File contents

You are analyzing a Java thread dump to identify deadlocks, performance issues, and thread contention.

Step 1: Capture the thread dump

If the user provided a file path, skip to Step 2.

If no file path was provided, help capture a thread dump from a running Gradle worker JVM:

Find Gradle worker processes:
```
jps -l | grep GradleWorkerMain
```
If multiple workers are found, ask the user which PID to analyze (or analyze all if requested)
Capture the thread dump:
```
jstack <PID> > /tmp/jstack-<PID>.txt
```
Proceed to analyze the captured dump file

Step 2: Analyze the thread dump

Launch a general-purpose Task subagent with the following instructions:

Read and analyze the jstack thread dump at: {{arg1}} (or the file path from Step 1)

Your analysis should identify:

Deadlocks - Any threads waiting on locks held by each other (jstack usually reports these at the top)
Blocked threads - Threads in BLOCKED state and what locks they're waiting for
Lock contention - Locks (monitors) with multiple threads waiting on them
Thread states distribution - Count of RUNNABLE, WAITING, TIMED_WAITING, BLOCKED threads
Thread pool health - Look for exhausted thread pools (e.g., all threads in pool are blocked/waiting)
Suspicious patterns - Threads stuck in the same operation, recursive locks, etc.
Hot code paths - Stack traces that appear frequently across threads

Provide:

Executive Summary - Critical issues found (deadlocks, severe contention, etc.)
Deadlock Analysis - Full details of any deadlock cycles with thread names, IDs, and lock objects
Thread Contention - Locks with high contention (multiple waiters) and what threads hold them
Thread State Overview - Statistics on thread states
Problematic Threads - Details on blocked/waiting threads with context
Code Locations - If identifiable, map issues to code locations in the codebase
Recommended Actions - Specific steps to resolve the issues

Format your response in clear markdown with sections for each category. Include relevant thread IDs, lock addresses, and stack trace excerpts to support findings.

---name: jstackdescription: You are analyzing a Java thread dump to identify deadlocks, performance issues, and thread contention.--- You are analyzing a Java thread dump to identify deadlocks, performance issues, and thread contention. ## Step 1: Capture the thread dump If the user provided a file path, skip to Step 2. If no file path was provided, help capture a thread dump from a running Gradle worker JVM: 1. Find Gradle worker processes: ```bash jps -l | grep GradleWorkerMain ``` 2. If multiple workers are found, ask the user which PID to analyze (or analyze all if requested) 3. Capture the thread dump: ```bash jstack <PID> > /tmp/jstack-<PID>.txt ``` 4. Proceed to analyze the captured dump file ## Step 2: Analyze the thread dump Launch a general-purpose Task subagent with the following instructions: **Read and analyze the jstack thread dump at: {{arg1}} (or the file path from Step 1)** Your analysis should identify: 1. **Deadlocks** - Any threads waiting on locks held by each other (jstack usually reports these at the top) 2. **Blocked threads** - Threads in BLOCKED state and what locks they're waiting for 3. **Lock contention** - Locks (monitors) with multiple threads waiting on them 4. **Thread states distribution** - Count of RUNNABLE, WAITING, TIMED_WAITING, BLOCKED threads 5. **Thread pool health** - Look for exhausted thread pools (e.g., all threads in pool are blocked/waiting) 6. **Suspicious patterns** - Threads stuck in the same operation, recursive locks, etc. 7. **Hot code paths** - Stack traces that appear frequently across threads **Provide:** - **Executive Summary** - Critical issues found (deadlocks, severe contention, etc.) - **Deadlock Analysis** - Full details of any deadlock cycles with thread names, IDs, and lock objects - **Thread Contention** - Locks with high contention (multiple waiters) and what threads hold them - **Thread State Overview** - Statistics on thread states - **Problematic Threads** - Details on blocked/waiting threads with context - **Code Locations** - If identifiable, map issues to code locations in the codebase - **Recommended Actions** - Specific steps to resolve the issues Format your response in clear markdown with sections for each category. Include relevant thread IDs, lock addresses, and stack trace excerpts to support findings.

Frequently asked questions

Jstack