mapbench_test.go

package mapbench_test

import "testing"

var N = 1000000

var m1 map[int]int = map[int]int{}

var m2 map[int]int = make(map[int]int, N)

func init() {
	for i := 0; i < N; i++ {
		m1[i] = i
		m2[i] = i
	}
}

func BenchmarkMap(b *testing.B) {
	for i := 0; i < b.N; i++ {
		s := 0
		for _, v := range m1 {
			s += v
		}
	}
}

func BenchmarkMapcap(b *testing.B) {
	for i := 0; i < b.N; i++ {
		s := 0
		for _, v := range m2 {
			s += v
		}
	}
}

result.txt

[2020](*'-')< ~$ go test mapbench_test.go -bench . -benchmem
testing: warning: no tests to run
PASS
BenchmarkMap	      50	  27253697 ns/op	       0 B/op	       0 allocs/op
BenchmarkMapcap	      50	  26253573 ns/op	       0 B/op	       0 allocs/op
ok  	command-line-arguments	3.474s
[2021](*'-')< ~$ go test mapbench_test.go -bench . -benchmem
testing: warning: no tests to run
PASS
BenchmarkMap	      50	  26995885 ns/op	       0 B/op	       0 allocs/op
BenchmarkMapcap	      50	  26377702 ns/op	       0 B/op	       0 allocs/op
ok  	command-line-arguments	3.466s
[2022](*'-')< ~$ go test mapbench_test.go -bench . -benchmem
testing: warning: no tests to run
PASS
BenchmarkMap	      50	  27062819 ns/op	       0 B/op	       0 allocs/op
BenchmarkMapcap	      50	  26590986 ns/op	       0 B/op	       0 allocs/op
ok  	command-line-arguments	3.474s
[2023](*'-')< ~$ go test mapbench_test.go -bench . -benchmem
testing: warning: no tests to run
PASS
BenchmarkMap	      50	  27514986 ns/op	       0 B/op	       0 allocs/op
BenchmarkMapcap	      50	  26706534 ns/op	       0 B/op	       0 allocs/op
ok  	command-line-arguments	3.506s
[2024](*'-')< ~$ go test mapbench_test.go -bench . -benchmem
testing: warning: no tests to run
PASS
BenchmarkMap	      50	  27476116 ns/op	       0 B/op	       0 allocs/op
BenchmarkMapcap	      50	  26293569 ns/op	       0 B/op	       0 allocs/op
ok  	command-line-arguments	3.476s