deadlock-detection-harness SKILL.md skillA
deadlock-detection-harness from testland/qa is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add testland/qa/deadlock-detection-harness@v1.2.12Pins v1.2.12 in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- testland/qa
- Path
plugins/qa-concurrency/skills/deadlock-detection-harness/SKILL.md- Versions recorded
- 5
- Latest version
- v1.2.12, committed Oct 11, 2026
- First version recorded
- Jul 6, 2026
- Size
- 7,776 bytes
- Repository stars
- 11
- License
- MIT
Build deadlock-detection harnesses - extract lock-acquire-order graph via instrumentation, run cycle detection (DFS) to spot inconsistent ordering, use lock-acquire timeouts to surface rather than hang, JVM `jstack` / `gdb thread apply all bt` for postmortem analysis. Pair with ThreadSanitizer's `detect_deadlocks=1` for runtime detection. Use when a service that holds two or more locks hangs in production with no crash or error, or before release when lock acquisition order across code paths…
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# deadlock-detection-harness
A deadlock = a cycle in the lock-wait graph: thread A holds X waiting
for Y; thread B holds Y waiting for X. Tests prevent deadlocks via
*static analysis of lock acquisition order* + *runtime detection*
(timeouts, sanitizer, postmortem dumps).
## When to use
- Service has multiple locks/mutexes and complex code paths.
- Production hang reported; need to (a) reproduce and (b) prevent
recurrence.
- Pre-release: `detect_deadlocks` ThreadSanitizer mode passes on
the test workload.
## Step 1 - Lock-order convention
Establish a strict ordering for all locks and document it:
```python
# Lock order (acquire low-numbered first; release high-numbered first)
LOCK_ORDER = {
"user_lock": 1,
"session_lock": 2,
"audit_lock": 3,
"db_lock": 4,
}
```
Any code that violates this order = potential deadlock. The
deadlock harness's job: detect violations.
## Step 2 - Instrument lock acquisitions
For Python (rough sketch using contextvars + decorator):
```python
import contextvars
import threading
acquired = contextvars.ContextVar("acquired", default=())
class OrderedLock:
def __init__(self, name, order):
…Read the whole file at its exact version.
How to install
mdr add testland/qa/deadlock-detection-harness@sha256:40aecece10d759aaThe line at the top of this page pins the label v1.2.12, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
[](https://markdownregistry.com/a/art_evnfnvzc6xuqkiiu)
1 badge image fetches in 30 days. What the badge shows.
Versions
The registry has recorded 5 versions of this file, between Jul 6, 2026 and Oct 11, 2026, about one every 24 days.
| version | committed | commit | size | audit | |
|---|---|---|---|---|---|
| v1.2.12 latest | 2026-10-11 | a1bd3f7 | 7,776 B | A | view · diff |
| git:20260724.d4db756 | 2026-07-24 | d4db756 | 7,756 B | A | view · diff |
| git:20260719.53f73b7 | 2026-07-19 | 53f73b7 | 7,834 B | A | view · diff |
| git:20260719.6226ac1 | 2026-07-19 | 6226ac1 | 7,644 B | A | view · diff |
| git:20260706.d9cec5f | 2026-07-06 | d9cec5f | 7,658 B | A | view |
Audit of the latest version
- pass: Frontmatter block present
- pass: Frontmatter declares a name
- pass: Frontmatter declares a description
- pass: Size between 200 bytes and 200 KB (7776 bytes)
- pass: No zero-width or bidi control characters
- pass: No instruction hidden inside an HTML comment
- pass: No link to an exfiltration or paste host
- pass: No credential-shaped string
- pass: No instruction to send local credentials anywhere
- pass: No text hidden with inline styles
- pass: No prompt-injection phrasing
- pass: No curl or wget piped into a shell
- pass: No recursive delete of root, home or parent
- pass: No instruction to read or print local credentials
- pass: No base64 blob over 200 characters
- pass: No link to a raw IP address
- pass: No script tag
Source
testland/qa · 11 stars · license MIT · pushed 2026-10-20 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_evnfnvzc6xuqkiiu GET https://markdownregistry.com/api/v1/resolve?ref=testland/qa/deadlock-detection-harness GET https://markdownregistry.com/api/v1/blob/40aecece10d759aa3162016d1aaf6aefd5b79e5b3b9ec64c505c9596a40f35da
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
Guides: the SKILL.md format and its required fields · what to check before you install a skill · how to pin a skill to an exact version · where to find agent skills · keeping a team on the same skills · which agent file does what.