Go makes it cheap to run work in the background and just as easy to leave it running forever — this is how to give each piece an owner, a way to stop, and safe access to data it shares.
WHEN TO USE
SCOPE
USE FOR
Choose between a channel, a mutex, or an atomic to protect one piece of shared state.
Design a worker pool or fan-out/fan-in pipeline with errgroup.SetLimit instead of hand-rolled code.
Review a pull request's concurrent code for goroutine leaks and a missing ctx.Done() case.
Decide between sync.WaitGroup, errgroup, and singleflight for a specific coordination need.
Audit an existing codebase for unbounded goroutine spawning and unprotected shared maps.
NOT FOR
Not for defensive-coding issues unrelated to concurrency, like nil panics or slice aliasing.
Not for debugging an already hung, crashed, or racing program after the fact.
This is a saved copy of the skill's SKILL.md instructions. It may differ from the upstream file or the version you install.
Persona: You are a Go concurrency engineer. You assume every goroutine is a liability until proven necessary — correctness and leak-freedom come before performance.
Orchestration mode: Fan out the five sub-agents described in the "Parallelizing Concurrency Audits" section for auditing concurrent code across a large codebase, and consolidate their findings into one report. On Claude Code, use ultracode to opt into multi-agent orchestration explicitly.
Review mode — reviewing a PR's concurrent code changes. Focus on the diff: check for goroutine leaks, missing context propagation, ownership violations, and unprotected shared state. Sequential.
Audit mode — auditing existing concurrent code across a codebase. Use up to 5 parallel sub-agents as described in the "Parallelizing Concurrency Audits" section.
Community default. A company skill that explicitly supersedes samber/cc-skills-golang@golang-concurrency skill takes precedence.
Go Concurrency Best Practices
Go's concurrency model is built on goroutines and channels. Goroutines are cheap but not free — every goroutine you spawn is a resource you must manage. The goal is structured concurrency: every goroutine has a clear owner, a predictable exit, and proper error propagation.
Core Principles
Every goroutine must have a clear exit — without a shutdown mechanism (context, done channel, WaitGroup), they leak and accumulate until the process crashes
Share memory by communicating — channels transfer ownership explicitly; mutexes protect shared state but make ownership implicit
Send copies, not pointers on channels — sending pointers creates invisible shared memory, defeating the purpose of channels
Only the sender closes a channel — closing from the receiver side panics if the sender writes after close
Specify channel direction (chan<-, <-chan) — the compiler prevents misuse at build time
Default to unbuffered channels — larger buffers mask backpressure; use them only with measured justification
Always include ctx.Done() in select — without it, goroutines leak after caller cancellation
Avoid repeated time.After in hot loops — each call allocates a timer and creates unnecessary churn; use time.NewTimer + Reset for long-running loops
Track goroutine leaks in tests with go.uber.org/goleak
No explicit locking; use RWMutex+map when writes dominate
sync.Pool
Reuse temporary objects
Always Reset() before Put(); reduces GC pressure
sync.Once
One-time initialization
Go 1.21+: OnceFunc, OnceValue, OnceValues
sync.WaitGroup
Waiting for simple goroutines
Go 1.25+: prefer wg.Go(func(){ ... }) for fire-and-wait tasks that do not panic and do not need error propagation. For Go <1.25 use Add/Done. For errors/cancellation/limits, use errgroup with context.
Find time.After in loops, missing ctx.Done() in select, unbounded spawning
Check mutex usage, sync.Map, atomics, and thread-safety documentation
Common Mistakes
Mistake
Fix
Fire-and-forget goroutine
Provide stop mechanism (context, done channel)
Closing channel from receiver
Only the sender closes
time.After in hot loop
Reuse time.NewTimer + Reset
Missing ctx.Done() in select
Always select on context to allow cancellation
Unbounded goroutine spawning
Use errgroup.SetLimit(n) or semaphore
Sharing pointer via channel
Send copies or immutable values
wg.Add inside goroutine
Call Add before go — Wait may return early otherwise
Forgetting -race in CI
Always run go test -race ./...
Mutex held across I/O
Keep critical sections short
Cross-References
→ See samber/cc-skills-golang@golang-performance skill for false sharing, cache-line padding, sync.Pool hot-path patterns
→ See samber/cc-skills-golang@golang-context skill for cancellation propagation and timeout patterns
→ See samber/cc-skills-golang@golang-safety skill for concurrent map access and race condition prevention
→ See samber/cc-skills-golang@golang-troubleshooting skill for debugging goroutine leaks and deadlocks
→ See samber/cc-skills-golang@golang-design-patterns skill for graceful shutdown patterns
→ See samber/cc-skills-golang@golang-continuous-integration skill for automated AI-driven code review in CI using these guidelines
Goroutine leak profile
The goroutine leak profile (experimental behind GOEXPERIMENT=goroutineleakprofile in Go 1.26) is generally available in runtime/pprof since Go 1.27 — no build flag required. It is a useful production-oriented leak signal alongside the existing tools below.
curl http://localhost:6060/debug/pprof/goroutineleak?debug=2
go tool pprof http://localhost:6060/debug/pprof/goroutineleak
Run this outside your AI tool, using Node.js 22.20.0 or newer. Skills CLI 1.7.2 skips skill selection; prompts cancel installation without an interactive terminal. If choosing Project when asked about installation scope, open your project's folder before running this.
Install checklist
Check selected tools if a picker appears; Claude Code may be unchecked under Additional agents. ↑/↓ moves, Space toggles selections, Enter confirms.
Without a tool picker, check Installing to: for your intended tool. Stop if it names a different tool.
If asked, choose Symlink (Recommended) for shared files or Copy to all agents for separate copies; review the summary before confirming installation.
Install the find-skills skill? defaults to Yes, adding another skill for all projects. Choose No if you don't want that extra installation.
Skills CLI 1.7.2 sends install data to skills.sh by default, including the source, skill names, target tools and file details; GitHub sources are reported only when GitHub confirms the repository is public, while other remote sources can also be reported. Confirmed-public GitHub sources also trigger a security-audit request. Before installing, set the environment variable DO_NOT_TRACK=1 or DISABLE_TELEMETRY=1 to disable both.
After installing for Claude Code, open it in the installation project if you chose Project; Global makes the skill available across projects on this computer. Once Claude Code loads the skill, its description helps Claude decide when to use it.
If installation created a top-level skills folder that did not exist when your Claude Code session started, run /reload-skills in that session. Run it again after later changes in that folder.
Install the whole plugin
This route installs the Samber Golang Skills plugin package selected for your AI tool.
Add Samuel's marketplace, then install the plugin
Type both lines inside a Claude Code session, not at your shell prompt. The marketplace is a separate repository of Samuel Berthe's, samber/cc, which also lists his other plugins. The second line opens the details of cc-skills-golang, which carries this repository's 46 Go skills; pick one of the install options shown and Claude Code installs it.
01
/plugin marketplace add samber/cc
02
/plugin install cc-skills-golang@samber
Run it in your terminal. It copies the whole repository, with its 46 skills, into ~/.openclaw/skills/cc-skills-golang, OpenClaw's skills folder in your home folder. To install it for one OpenClaw workspace instead, Samuel gives ~/.openclaw/workspace/skills/cc-skills-golang as the folder.
Run it in your terminal, not inside Gemini CLI; installing from GitHub needs git on your computer. It installs the repository, with its 46 skills, as a Gemini CLI extension. To update it later, run gemini extensions update cc-skills-golang.
Run it in your terminal. It copies the whole repository, with its 46 skills, into ~/.cursor/skills/cc-skills-golang, Cursor's skills folder in your home folder.
Type it in an interactive GitHub Copilot CLI session, not at your shell prompt. It installs the repository straight from GitHub as a plugin, with its 46 skills and no marketplace to add first.
Golang benchmarking, profiling, and performance measurement. Use when writing, running, or comparing Go benchmarks, profiling hot paths with pprof, interpreting CPU/memory/trace profiles, analyzing results with benchstat, setting up CI benchmark regression detection, or investigating production performance with Prometheus runtime metrics. Also use when the developer needs deep analysis on a specific performance indicator - this skill provides the measurement methodology, while samber/cc-skills-golang@golang-performance provides the optimization patterns.Read full description
Golang CLI application development. Use when building, modifying, or reviewing a Go CLI tool — especially for command structure, flag handling, configuration layering, version embedding, exit codes, I/O patterns, signal handling, shell completion, argument validation, and CLI unit testing. Also triggers when code uses cobra, viper, or urfave/cli. For cobra-specific APIs → See samber/cc-skills-golang@golang-spf13-cobra skill; for viper configuration layering → See samber/cc-skills-golang@golang-spf13-viper skill.Read full description
Golang code style conventions — line length and breaking, variable declarations, control flow clarity, when comments help vs hurt. Use when writing or reviewing Go code, asking about style or clarity, or establishing project coding standards. Not for naming conventions (→ See samber/cc-skills-golang@golang-naming skill), linter configuration (→ See samber/cc-skills-golang@golang-lint skill), or doc comments (→ See samber/cc-skills-golang@golang-documentation skill).Read full description
Idiomatic context.Context usage in Golang — propagation through API boundaries, cancellation, timeouts and deadlines, request-scoped values, context.WithoutCancel for background work outliving requests. Apply when designing context propagation across layers, debugging leaked or unexpired contexts, choosing between context.Background/TODO/WithoutCancel, or storing values in context. Not for code that merely accepts ctx as first parameter.Read full description
CI/CD pipeline configuration using GitHub Actions for Golang projects — testing, linting, SAST, security scanning, code coverage, Dependabot, Renovate, GoReleaser, code review automation, and release pipelines. Use when setting up or improving Go project CI, configuring GitHub Actions workflows, adding linters or security scanners, automating dependency updates, or adding quality gates.Read full description
Golang data structures — slices (internals, capacity growth, preallocation, slices package), maps (internals, hash buckets, maps package), arrays, container/list/heap/ring, strings.Builder vs bytes.Buffer, generic collections, pointers (unsafe.Pointer, weak.Pointer), and copy semantics. Use when choosing or optimizing Go data structures, implementing generic containers, using container/ packages, unsafe or weak pointers, or questioning slice/map internals. Not for applying optimization patterns once profiling has identified a bottleneck (→ See samber/cc-skills-golang@golang-performance skill).Read full description
