golang-concurrency

Golang concurrency patterns. Use when writing or reviewing concurrent Go code involving goroutines, channels, select, locks, sync primitives, errgroup, singleflight, worker pools, or fan-out/fan-in pipelines. Also triggers when you detect goroutine leaks, race conditions, channel ownership issues, or need to choose between channels and mutexes.

1.18x

Quality

81%

Does it follow best practices?

Impact

98%

1.18x

Average score across 3 eval scenarios

Securityby

Passed

No known issues

Evaluation results

94%

Concurrent Job Queue with Test Coverage

Goroutine leak detection in tests

Criteria

Without context

With context

goleak import

100%

goleak in TestMain

100%

TestMain signature

100%

Race flag usage

100%

Context-based goroutine exit

100%

WaitGroup Add before go

100%

Channel direction in functions

50%

Sender closes channel

62%

75%

ctx.Done in select

100%

No time.After in loops

100%

24%

Service Metrics Collector

Typed atomics and mutex embedding

Criteria

Without context

With context

Typed atomic counter

100%

Typed atomic flag

100%

Mutex above protected fields

100%

Mutex is unexported

100%

RWMutex for read-heavy fields

100%

No mutex across I/O

100%

Atomic over mutex for simple values

100%

sync.Map only for read-heavy

100%

No RLock-to-Lock upgrade

100%

Context-based goroutine lifecycle

100%

18%

Distributed Report Generator

sync.Once modern helpers and wg.Go

Criteria

Without context

With context

OnceValue or OnceFunc usage

100%

wg.Go() for goroutines

100%

errgroup.SetLimit for bounded fan-out

100%

errgroup.WithContext cancellation

100%

No unbounded goroutine spawning

100%

ctx.Done in select

100%

Channel direction specified

100%

Sender closes channel

100%

No hand-rolled worker pool

100%

Repository: samber/cc-skills-golang
Commit: e9761db

Evaluated: 1 day ago
Agent: Claude Code
Model: Claude Sonnet 4.6

Table of Contents

Concurrent Job Queue with Test Coverage Service Metrics Collector Distributed Report Generator

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