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 tienenwu/fables --skill go-concurrencygit clone --depth 1 https://github.com/tienenwu/fablesWrote 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/tienenwu/fables/go-concurrency)<a href="https://agentmods.dev/skills/tienenwu/fables/go-concurrency"><img src="https://agentmods.dev/badge/skills/tienenwu/fables/go-concurrency/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/tienenwu/fables/go-concurrency"><img src="https://agentmods.dev/badge/skills/tienenwu/fables/go-concurrency.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 | $0.00086 | $0.01561 |
| Opus 5 | $0.00043 | $0.00781 |
| Sonnet 5 | $0.00017 | $0.00312 |
| Haiku 4.5 | $0.00009 | $0.00156 |
Grade A, and why
go-concurrency-playbook 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 — 62 lines — stays where its author put it; the contents beside it link to each section on GitHub.
🌐 繁體中文（canonical） · English mirror
Go High-Concurrency Judgment Handbook
Prerequisite: single-machine correctness (the error three-way choice, the three classic goroutine leaks, nil interface, context rules, channel vs mutex, project structure) lives in backend-server's references/go.md; this handbook does not repeat it. This handbook picks up from "it runs correctly on one machine" and moves up to "it still holds when ten thousand requests pour in at once."
Core Principles
- Concurrency is a design decision, not a speed button: before spawning a goroutine, ask "is the bottleneck really here?" Adding concurrency without evidence of a bottleneck only turns bugs into concurrent bugs.
- Any unbounded buffer is a deferred OOM: every boundary where production might outpace consumption needs to be bounded + have an explicit "what happens when it's full" decision (pick one of block / drop / reject).
- For high-concurrency problems, look at "waiting" first, not CPU: the investigation order is goroutine profile (leaks/blocking) → lock contention → CPU → trace (scheduling). Most "slowness" is waiting on a lock, on a downstream, or on the scheduler — not slow computation.
- "Feels slow" is forbidden as a reason to change code directly: profile for evidence before acting; adding goroutines / caches / swapping data structures on a hunch usually fixes the wrong place and makes it slower.
- Problems that only blow up in production can only be verified with load testing: low-traffic single-machine runs have zero evidentiary weight for "leaks, lock contention, pool saturation, GOMAXPROCS misconfiguration" — these only surface under load at the target RPS.
Kickoff Routing
| Situation | Path | Read first |
|---|---|---|
| Thinking "spawn a few goroutines to speed it up" | First confirm the bottleneck and whether concurrency is even needed, then decide on a pool | references/concurrency-patterns.md §1 |
| Need a worker pool / bounded concurrency / fan-out | Set worker count and bounds, pick the right primitive | references/concurrency-patterns.md |
| Multiple subtasks to run in parallel + error propagation/cancellation | errgroup, not a bare WaitGroup | references/concurrency-patterns.md §3 |
| High-concurrency reads on the same key + expensive origin fetch | singleflight to prevent cache stampede | references/concurrency-patterns.md §5 |
| Wiring a channel/queue, fear OOM, setting timeouts | Bounded + backpressure + timeout budget decreasing layer by layer | references/backpressure-limits.md |
| Adding rate limit / throttling / circuit breaker / load shedding | Selection and the "is it really needed" criterion | references/backpressure-limits.md |
| Service got slow, need to tune performance | Profile for evidence first, don't change anything yet | references/performance-profiling.md |
| Suspect lock contention / GC pressure | mutex/block profile, fix priority order | references/performance-profiling.md |
| Before a release / going to high traffic | Run the mandatory checklist item by item (load testing is a hard requirement) | references/release-checklist.md |
What ships with it
5 files 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.
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 · 62 lines · 86 tokens per session scan A 77184c98e7df
go-concurrency-playbook is a skill published in the GitHub repository tienenwu/fables (4 stars, last pushed 1mo ago), licensed MIT. It adds 86 tokens to every session and 1,561 once invoked, about $0.0004 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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