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.
npx skills add mickeyyaya/refactoring-skills --skill concurrency-patternsgit clone --depth 1 https://github.com/mickeyyaya/refactoring-skillsWrote 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.
[](https://agentmods.dev/skills/mickeyyaya/refactoring-skills/concurrency-patterns)<a href="https://agentmods.dev/skills/mickeyyaya/refactoring-skills/concurrency-patterns"><img src="https://agentmods.dev/badge/skills/mickeyyaya/refactoring-skills/concurrency-patterns/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.
<a href="https://agentmods.dev/skills/mickeyyaya/refactoring-skills/concurrency-patterns"><img src="https://agentmods.dev/badge/skills/mickeyyaya/refactoring-skills/concurrency-patterns.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00067 | $0.03345 |
| Opus 5 | $0.00034 | $0.01673 |
| Sonnet 5 | $0.00013 | $0.00669 |
| Haiku 4.5 | $0.00007 | $0.00334 |
Grade A, and why
concurrency-patterns 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 9d 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.
How it starts
The opening of the file, as written. The whole thing — 401 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Concurrency Patterns for Code Review
Overview
Concurrency bugs are among the hardest to reproduce: they appear non-deterministically, are invisible in unit tests, and can cause data corruption in production. Use this guide during code review to catch concurrency hazards before they ship.
When to Use
- Reviewing code that accesses shared state from multiple threads or coroutines
- Reviewing async/await code for hidden bottlenecks or error-swallowing
- Evaluating background task queues, worker pools, or message-passing systems
- Code touching databases, caches, or files from concurrent request handlers
Quick Reference
| Pattern | Core Idea | Primary Red Flag |
|---|---|---|
| Race Conditions | Multiple threads read-modify-write shared state | Unsynchronized count++, check-then-act without lock |
| Deadlocks | Circular wait on two or more locks | Nested lock acquisition in inconsistent order |
| Thread Safety | Ensuring shared resources are safe to use concurrently | Mutable fields accessed without synchronization |
| Immutable Data | Eliminate races by sharing only read-only values | Passing mutable objects across thread boundaries |
| Producer-Consumer | Decouple work creation from execution via queue | Unbounded queue, missing backpressure |
| Actor Model | Isolated state, message-only communication | Shared mutable state between actors, blocking in actor |
| Thread Pool | Reuse threads instead of creating per-request | Thread-per-request at scale, pool exhaustion |
| Async/Await Pitfalls | Common mistakes in async code | Fire-and-forget without error handler, blocking in async |
| Read-Write Locks | Multiple readers OR single writer | Write-heavy workload using RWLock (more overhead than mutex) |
| Compare-and-Swap | Lock-free atomic update via CAS loop | ABA problem, spin loop without backoff |
Patterns in Detail
1. Race Conditions
Red Flags:
- Unsynchronized
count++— read-modify-write is three operations, not one - Check-then-act without lock:
if (!map.containsKey(k)) { map.put(k, v); } - Lazy init without synchronization:
if (instance == null) instance = new Foo() - Multiple fields updated separately when they should be atomic
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.
- 9d ago First seen · 401 lines · 67 tokens per session scan A 9b6974aaaf8a
concurrency-patterns is a skill published in the GitHub repository mickeyyaya/refactoring-skills (6 stars, last pushed 5mo ago), licensed MIT. It adds 67 tokens to every session and 3,345 once invoked, about $0.0003 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 2026-08-31.
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