concurrency-debugging

concurrency-debugging is a skill for Codex from OutlineDriven/outline-driven-development. It costs 40 tokens per session (1,668 once invoked), scanned A, original, Apache-2.0.

A read-only guide for diagnosing concurrency problems, where multiple threads run at the same time and can interfere with one another. It covers data races, deadlocks, lock ordering, and atomic operations.

In plain words
What is it for?
Use it to analyse race reports, inspect deadlocked threads with GDB, review C++ atomic access, and describe how to verify the fix.
Why use it?
It turns reports from tools such as ThreadSanitizer and Helgrind, or symptoms such as a hung process, into a named cause and a proposed fix.

Skill for Codex

Written for Codex: agents/openai.yaml present.

Good fit Use it to analyse race reports, inspect deadlocked threads with GDB, review C++ atomic access, and describe how to verify the fix.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/outlinedriven/outline-driven-development/concurrency-debugging
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.

Any agent
npx skills add OutlineDriven/outline-driven-development --skill concurrency-debugging
Clone the repo
git clone --depth 1 https://github.com/OutlineDriven/outline-driven-development

Made for: Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for concurrency-debugging

README.md
[![agentmods](https://agentmods.dev/badge/skills/outlinedriven/outline-driven-development/concurrency-debugging/github.svg)](https://agentmods.dev/skills/outlinedriven/outline-driven-development/concurrency-debugging)
Your own site
<a href="https://agentmods.dev/skills/outlinedriven/outline-driven-development/concurrency-debugging"><img src="https://agentmods.dev/badge/skills/outlinedriven/outline-driven-development/concurrency-debugging/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for concurrency-debugging

Your own site · 80×15
<a href="https://agentmods.dev/skills/outlinedriven/outline-driven-development/concurrency-debugging"><img src="https://agentmods.dev/badge/skills/outlinedriven/outline-driven-development/concurrency-debugging.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 40 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,668 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
Origin original No closer match found in the catalogue.
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 5.1 $0.00040 $0.01668
Opus 5 $0.00020 $0.00834
Sonnet 5 $0.00008 $0.00334
Haiku 4.5 $0.00004 $0.00167

Measured 3d ago against content hash 4e2313e5b3f4, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

concurrency-debugging 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 3d ago.

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.

.devin/skills/concurrency-debugging/SKILL.md · 130 lines

How it starts

The opening of the file, as written. The whole thing — 130 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Concurrency debugging

Contract

Field Bound contract
Trigger A ThreadSanitizer or Helgrind report needs reading, a process hangs in a suspected deadlock, std::atomic usage needs review, or a cross-thread access needs a happens-before justification.
Authority Read-only. Emits analysis and commands for the operator to run on the target; no file writes, no rollback needed. No remote mutation.
Side effect Diagnostic commands and a verdict in chat. Nothing is written.
Done The race or deadlock is named by its two conflicting accesses or its lock cycle, the fix is stated, and the verification run is described.

Inputs

  1. Symptom (required): a TSan or Helgrind report, a hung or deadlocked process, or code under review.
  2. Build access (required for TSan and Helgrind): the project rebuilds with a sanitizer flag or runs under Valgrind.
  3. Source (required): the code paths named in the report.

Procedure

  1. Detect the race with ThreadSanitizer. TSan ships inside GCC and Clang; it needs no separate install.

    gcc -fsanitize=thread -g -O1 -o prog main.c    # clang takes the same flags
    ./prog
    TSAN_OPTIONS="halt_on_error=1:second_deadlock_stack=1" ./prog
    

    halt_on_error stops at the first report. second_deadlock_stack adds the other lock stack to deadlock reports. Done when: the instrumented binary runs and a report exists, or the run is clean.

  2. Read the TSan report. A report names the access type and address, the stack of the thread that performed it, the stack of the conflicting earlier access, and where each thread was created. The race is the pair of accesses on one address with no synchronization between them.

    WARNING: ThreadSanitizer: data race (pid=12345)
      Write of size 4 at 0x7f1234 by thread T2:
        #0 increment /src/counter.c:8:5
      Previous read of size 4 at 0x7f1234 by thread T1:
        #0 read_counter /src/counter.c:3:14
      Thread T2 created at:
        #0 pthread_create ...
        #1 main /src/counter.c:28:3
    SUMMARY: ThreadSanitizer: data race /src/counter.c:8:5 in increment
    

Read the full file on GitHub · 130 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 3d ago First seen · 130 lines · 40 tokens per session scan A 4e2313e5b3f4

Subscribe to this mod's changes

concurrency-debugging is a skill published in the GitHub repository OutlineDriven/outline-driven-development (52 stars, last pushed 3d ago), licensed Apache-2.0. It adds 40 tokens to every session and 1,668 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-06.

Related

Other skills, from other repositories

memory-safety-patterns

Implement memory-safe programming with RAII, ownership, smart pointers, and resource management across Rust, C++, and C. Use when writing safe systems code, managing resources, or preventing memory bugs.

rmyndharis/antigravity-skills · 45 tokens

cpp

Comprehensive C/C++ programming reference covering everything from C11-C23 and C++11-C++23, system programming, CUDA GPU computing, debugging tools, Rust interop, and advanced topics. Use for: C/C++ questions, C/C++ interview preparation, modern language features, RAII/memory management, templates/generics, CUDA…

crazyguitar/cppcheatsheet · 0 tokens

cpp-debugging

Use when a C++ failure involves memory lifetime, undefined behavior, native crashes, or debugger-only state — debug with symbols, sanitizers, and platform-native debuggers before patching symptoms.

drvoss/everything-copilot-cli · 42 tokens

memory-safety-patterns

Implement memory-safe programming with RAII, ownership, smart pointers, and resource management across Rust, C++, and C. Use when writing safe systems code, managing resources, or preventing memory bugs.

RudyCity/superagent · 45 tokens

gcc

GCC compiler skill for C/C++ projects. Use when selecting optimization levels, warning flags, debug builds, LTO, sanitizer instrumentation, or diagnosing compilation errors with GCC. Covers flag selection for debug vs release, ABI concerns, preprocessor macros, profile-guided optimization, and integration with build…

mohitmishra786/low-level-dev-skills · 85 tokens

cuopt-developer

Modify, build, test, debug, and contribute to NVIDIA cuOpt (C++/CUDA, Python, server, CI). Use for solver internals, PRs, DCO, and code conventions.

NVIDIA/skills · 47 tokens