test map hint

test map hint

stirabos@t14s:/tmp/mapt$ cat main.go 
package main

func main() {}

var srcLabels = map[string]string{
	"app":                          "kubevirt-hyperconverged",
	"app.kubernetes.io/component":  "compute",
	"app.kubernetes.io/managed-by": "hco-operator",
	"app.kubernetes.io/part-of":    "hyperconverged-cluster",
	"app.kubernetes.io/version":    "4.14.3",
	"userk0":                       "userv0",
	"userk1":                       "userv1",
	"userk2":                       "userv2",
	"userk3":                       "userv3",
	"userk4":                       "userv4",
	"userk5":                       "userv5",
	"userk6":                       "userv6",
	"userk7":                       "userv7",
	"userk8":                       "userv8",
	"userk9":                       "userv9",
}

func MapWithHint() {
	m := make(map[string]string, len(srcLabels))
	for key, val := range srcLabels {
		m[key] = val
	}
}

func MapWithoutHint() {
	m := make(map[string]string)
	for key, val := range srcLabels {
		m[key] = val
	}
}

stirabos@t14s:/tmp/mapt$ cat main_test.go 
package main

import "testing"

func Benchmark_Hint(b *testing.B) {
	for i := 0; i < b.N; i++ {
		MapWithHint()
	}
}

func Benchmark_WithoutHint(b *testing.B) {
	for i := 0; i < b.N; i++ {
		MapWithoutHint()
	}
}

stirabos@t14s:/tmp/mapt$ go test -bench=. -benchtime=10s
goos: linux
goarch: amd64
pkg: example.com/m
cpu: Intel(R) Core(TM) i7-10610U CPU @ 1.80GHz
Benchmark_Hint-8          	14231425	       822.9 ns/op
Benchmark_WithoutHint-8   	 8742591	      1460 ns/op
PASS
ok  	example.com/m	26.720s