Getting it into your agent
It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.
git clone --depth 1 https://github.com/muratmirgun/gophersnpx agentmods add skills/muratmirgun/gophers/go-concurrencyWrote 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/muratmirgun/gophers/go-concurrency)<a href="https://agentmods.dev/skills/muratmirgun/gophers/go-concurrency"><img src="https://agentmods.dev/badge/skills/muratmirgun/gophers/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/muratmirgun/gophers/go-concurrency"><img src="https://agentmods.dev/badge/skills/muratmirgun/gophers/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 | $0.00085 | $0.02179 |
| Opus 5 | $0.00043 | $0.01090 |
| Sonnet 5 | $0.00017 | $0.00436 |
| Haiku 4.5 | $0.00009 | $0.00218 |
Grade A, and why
go-concurrency scanned grade A with 1 finding 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.
Makes network callslowCapability
Not a fault in itself. Listed so you know the mod talks to something, and to what.
g.Go(func() error { return fetch(ctx, url) }) How it starts
The opening of the file, as written. The whole thing — 145 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Go Concurrency
Goroutines are cheap, but every one you spawn is a resource you must own. The goal is structured concurrency: each goroutine has a clear owner, a predictable exit, and a way for the caller to wait and collect errors.
Core Rules
- Never start a goroutine without knowing how it will stop. A blocked goroutine is not garbage-collected — it leaks.
- The caller must be able to wait. Use
sync.WaitGroup,errgroup.Group, or an explicit done channel. - No goroutines in
init(). ExposeStart/Stop/Shutdownso callers control the lifecycle. - Share by communicating. Default to channels; reach for
sync.Mutexonly when the problem is genuinely "protect a shared field". - Only the sender closes a channel. Closing from the receiver side panics on the next send.
- Specify channel direction (
chan<-,<-chan) at function boundaries — the compiler catches misuse. - Always include
ctx.Done()inselect. Without it, the goroutine cannot be cancelled. - Test for leaks with
go.uber.org/goleak.
Primitive Decision
| Need | Use | Why |
|---|---|---|
| Pass a value from producer to consumer | Channel | Transfers ownership explicitly |
| Wait for N fire-and-forget goroutines | sync.WaitGroup (Go 1.25: wg.Go) |
No error needed |
| Wait + collect first error + cancel siblings | errgroup.WithContext |
Structured failure |
| Bound concurrency (worker pool) | errgroup.SetLimit(n) |
Replaces hand-rolled pools |
| Protect a shared field | sync.Mutex / sync.RWMutex |
Short critical section |
| Counter / flag | typed sync/atomic (atomic.Int64, atomic.Bool) |
Lock-free, type-safe |
| Read-heavy concurrent map | sync.Map |
Concurrent map read/write otherwise crashes |
| One-shot init | sync.Once (or OnceFunc/OnceValue in 1.21+) |
Idempotent setup |
| Deduplicate concurrent calls | x/sync/singleflight |
Cache stampede prevention |
Read references/sync-primitives.md when picking between mutex, atomic,
sync.Map,sync.Pool, orsingleflight, or when designing the field layout of a struct that protects shared state.
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 · 145 lines · 85 tokens per session scan A 0b08ef11a5f5
go-concurrency is a skill published in the GitHub repository muratmirgun/gophers (8 stars, last pushed 29d ago), licensed MIT. It adds 85 tokens to every session and 2,179 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
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