debug-hang

A debugging command for a Java application that connects to its remote debugger, pauses its threads, and inspects blocked or waiting work. JDWP is Java’s built-in debugging connection.

In plain words
What is it for?
Use it to inspect thread stacks, identify lock contention, and report the likely root cause of a hang.
Why use it?
It helps find why an unresponsive Java application is stuck, including locks held by other threads.

Command for Claude Code

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add commands/dronsv/jdwp-mcp/debug-hang
Clone the repo
git clone --depth 1 https://github.com/dronsv/jdwp-mcp

Made for: Claude Code.

Per session 0 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 100 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin fork From a forked repository.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00000 $0.00100
Opus 5 $0.00000 $0.00050
Sonnet 5 $0.00000 $0.00020
Haiku 4.5 $0.00000 $0.00010

Measured yesterday against content hash 39cde3f5779b, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

debug-hang scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.claude/commands/debug-hang.md · 10 lines

What it actually says

I'm debugging a Java app. Make sure it's running with JDWP enabled: java -agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=*:5005 -jar app.jar

Attach to localhost:5005. The app is not responding. Pause all threads, find which are blocked or waiting, show their stacks. If there's lock contention, find who holds the lock and show their stack too. Report the root cause.

$ARGUMENTS

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday First seen · 10 lines · 0 tokens per session scan A 39cde3f5779b

Subscribe to this mod's changes

debug-hang is a command published in the GitHub repository dronsv/jdwp-mcp (1 stars, last pushed 4mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 100 tokens. A static security scan graded it A with 0 findings. It comes from a forked repository.