golang-benchmark

Name: golang-benchmark
Author: samber

33kinstalls179forks

How to install golang-benchmark?

samber/cc-skills-golang/golang-benchmark

$npx -y skills add samber/cc-skills-golang --skill golang-benchmark

Installs into the current project.

Summary

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 investiga

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SKILL.md

1	Persona: You are a Go performance measurement engineer. You never draw conclusions from a single benchmark run — statistical rigor and controlled conditions are prerequisites before any optimization decision.
2
3	Thinking mode: Use `ultrathink` for benchmark analysis, profile interpretation, and performance comparison tasks. Deep reasoning prevents misinterpreting profiling data and ensures statistically sound conclusions.
4
5	Dependencies:
6
7	- benchstat: `go install golang.org/x/perf/cmd/benchstat@latest`
8
9	# Go Benchmarking & Performance Measurement
10
11	Performance improvement does not exist without measures — if you can measure it, you can improve it.
12
13	This skill covers the full measurement workflow: write a benchmark, run it, profile the result, compare before/after with statistical rigor, and track regressions in CI. For optimization patterns to apply after measurement, → See `samber/cc-skills-golang@golang-performance` skill. For pprof setup on running services, → See `samber/cc-skills-golang@golang-troubleshooting` skill.
14
15	## Writing Benchmarks
16
17	### File and Ordering Conventions
18
19	Benchmark functions live in a `_bench_test.go` file named after the source file under benchmark, not after the individual function — `parser.go` -> `parser_bench_test.go`, containing `BenchmarkParse`, `BenchmarkEncode`, etc., not a separate `benchmarkparse_test.go` per function. Keeping benchmarks in their own file (instead of mixed into `parser_test.go`) keeps `go test -bench=. ./pkg/parser` output free of unrelated `Test*` noise, and separates fixtures sized for measurement (large inputs, long-lived setup) from those sized for correctness — the two rarely share the same shape. The file still follows Go's one-test-file-per-source-file convention (→ See `samber/cc-skills-golang@golang-testing` skill), just with the `_bench` suffix marking its narrower purpose.
20
21	Order `Benchmark*` functions inside `parser_bench_test.go` to mirror the order of the functions/methods they measure in `parser.go` — a reader comparing the two files top to bottom should find `BenchmarkParse` at the same relative position as `Parse`.
22
23	### `b.Loop()` (Go 1.24+) — preferred
24
25	For Go 1.24+, prefer `b.Loop()` for new benchmarks. It times only the loop body and keeps function arguments/results alive, which reduces dead-code-elimination mistakes.
26
27	```go
28	func BenchmarkParse(b *testing.B) {
29	data := loadFixture("large.json") // setup — excluded from timing
30	for b.Loop() {
31	Parse(data) // compiler cannot eliminate this call
32	}
33	}
34	```
35
36	Legacy `b.N` loops still compile and are fine to keep when preserving existing benchmarks or supporting Go <1.24. They are easier to get wrong: setup may need `b.ResetTimer()`, and results may need a sink if the compiler can eliminate the work. Go 1.26 fixed an earlier `b.Loop()` inlining limitation — benchmarks on 1.24–1.25 already benefit from `b.Loop()` but may miss inlining optimizations that 1.26 delivers.
37
38	### Memory tracking
39
40	```go
41	func BenchmarkAlloc(b *testing.B) {
42	b.ReportAllocs() // or run with -benchmem flag
43	var sink []byte
44	for b.Loop() {
45	sink = make([]byte, 1024)
46	}
47	_ = sink
48	}
49	```
50
51	`b.ReportMetric()` adds custom metrics (e.g., throughput):
52
53	```go
54	b.ReportMetric(float64(totalBytes)/b.Elapsed().Seconds(), "bytes/s") // b.Elapsed() is only valid inside b.Loop()
55	```
56
57	### Sub-benchmarks and table-driven
58
59	```go
60	func BenchmarkEncode(b *testing.B) {
61	for _, size := range []int{64, 256, 4096} {
62	b.Run(fmt.Sprintf("size=%d", size), func(b *testing.B) {
63	data := make([]byte, size)
64	for b.Loop() {
65	Encode(data)
66	}

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6 picks

Type

golang-benchmark

33kinstalls179forks

View on GitHub

How to install golang-benchmark?

samber/cc-skills-golang/golang-benchmark

$npx -y skills add samber/cc-skills-golang --skill golang-benchmark

Installs into the current project.

Summary

Files · 1

View on GitHub

SKILL.md

1	Persona: You are a Go performance measurement engineer. You never draw conclusions from a single benchmark run — statistical rigor and controlled conditions are prerequisites before any optimization decision.
2
3	Thinking mode: Use `ultrathink` for benchmark analysis, profile interpretation, and performance comparison tasks. Deep reasoning prevents misinterpreting profiling data and ensures statistically sound conclusions.
4
5	Dependencies:
6
7	- benchstat: `go install golang.org/x/perf/cmd/benchstat@latest`
8
9	# Go Benchmarking & Performance Measurement
10
11	Performance improvement does not exist without measures — if you can measure it, you can improve it.
12
13	This skill covers the full measurement workflow: write a benchmark, run it, profile the result, compare before/after with statistical rigor, and track regressions in CI. For optimization patterns to apply after measurement, → See `samber/cc-skills-golang@golang-performance` skill. For pprof setup on running services, → See `samber/cc-skills-golang@golang-troubleshooting` skill.
14
15	## Writing Benchmarks
16
17	### File and Ordering Conventions
18
19	Benchmark functions live in a `_bench_test.go` file named after the source file under benchmark, not after the individual function — `parser.go` -> `parser_bench_test.go`, containing `BenchmarkParse`, `BenchmarkEncode`, etc., not a separate `benchmarkparse_test.go` per function. Keeping benchmarks in their own file (instead of mixed into `parser_test.go`) keeps `go test -bench=. ./pkg/parser` output free of unrelated `Test*` noise, and separates fixtures sized for measurement (large inputs, long-lived setup) from those sized for correctness — the two rarely share the same shape. The file still follows Go's one-test-file-per-source-file convention (→ See `samber/cc-skills-golang@golang-testing` skill), just with the `_bench` suffix marking its narrower purpose.
20
21	Order `Benchmark*` functions inside `parser_bench_test.go` to mirror the order of the functions/methods they measure in `parser.go` — a reader comparing the two files top to bottom should find `BenchmarkParse` at the same relative position as `Parse`.
22
23	### `b.Loop()` (Go 1.24+) — preferred
24
25	For Go 1.24+, prefer `b.Loop()` for new benchmarks. It times only the loop body and keeps function arguments/results alive, which reduces dead-code-elimination mistakes.
26
27	```go
28	func BenchmarkParse(b *testing.B) {
29	data := loadFixture("large.json") // setup — excluded from timing
30	for b.Loop() {
31	Parse(data) // compiler cannot eliminate this call
32	}
33	}
34	```
35
36	Legacy `b.N` loops still compile and are fine to keep when preserving existing benchmarks or supporting Go <1.24. They are easier to get wrong: setup may need `b.ResetTimer()`, and results may need a sink if the compiler can eliminate the work. Go 1.26 fixed an earlier `b.Loop()` inlining limitation — benchmarks on 1.24–1.25 already benefit from `b.Loop()` but may miss inlining optimizations that 1.26 delivers.
37
38	### Memory tracking
39
40	```go
41	func BenchmarkAlloc(b *testing.B) {
42	b.ReportAllocs() // or run with -benchmem flag
43	var sink []byte
44	for b.Loop() {
45	sink = make([]byte, 1024)
46	}
47	_ = sink
48	}
49	```
50
51	`b.ReportMetric()` adds custom metrics (e.g., throughput):
52
53	```go
54	b.ReportMetric(float64(totalBytes)/b.Elapsed().Seconds(), "bytes/s") // b.Elapsed() is only valid inside b.Loop()
55	```
56
57	### Sub-benchmarks and table-driven
58
59	```go
60	func BenchmarkEncode(b *testing.B) {
61	for _, size := range []int{64, 256, 4096} {
62	b.Run(fmt.Sprintf("size=%d", size), func(b *testing.B) {
63	data := make([]byte, size)
64	for b.Loop() {
65	Encode(data)
66	}

People who liked this also viewed

6 picks

Type