go map access

bench.txt

# go test -bench . -benchmem
goos: darwin
goarch: amd64
BenchmarkMap1-4           100000             24314 ns/op            2800 B/op        280 allocs/op
BenchmarkMap2-4            50000             25083 ns/op            2800 B/op        280 allocs/op

map_test.go

package main

import (
	"testing"
	"fmt"
)

func createItems(prefix string, num int) []string {
	items := make([]string, num)
	for i := 0; i < num; i++ {
		items[i] = fmt.Sprintf("%s_%04d", prefix, i)
	}

	return items
}


func BenchmarkMap1(b *testing.B) {
	mains := createItems("main", 1000)
	subs := createItems("sub", 1000)
	var total int
	
	maps := make(map[string]map[string]int)
	for _, main := range mains {
		maps[main] = make(map[string]int)
		for _, sub := range subs {
			total++
			maps[main][sub] = total
		}
	}

    b.ResetTimer()
    for i := 0; i < b.N; i++ {
		for j := 10; j < 80; j++ {
			mkey := fmt.Sprintf("main_%04d", j)
			skey := fmt.Sprintf("sub_%04d", j)
			if _, ok := maps[mkey][skey]; !ok {
				b.Errorf("map1 error: main = %s, sub = %s", mkey, skey)
			}
		}
    }
}

func BenchmarkMap2(b *testing.B) {
	mains := createItems("main", 1000)
	subs := createItems("sub", 1000)
	var total int
	
	maps := make(map[string]int)
	for _, main := range mains {
		for _, sub := range subs {
			total++
			key := main + "_" + sub
			maps[key] = total
		}
	}

    b.ResetTimer()
    for i := 0; i < b.N; i++ {
		for j := 10; j < 80; j++ {
			mkey := fmt.Sprintf("main_%04d", j)
			skey := fmt.Sprintf("sub_%04d", j)
			if _, ok := maps[mkey + "_" + skey]; !ok {
				b.Errorf("map2 error: main = %s, sub = %s", mkey, skey)
			}
		}
    }	
}