This sample script is for retrieving values from a deep nested JSON. There are 2 patterns. So for these, the benchmark were measured.
Script :
package main
import (
"encoding/json"
"testing"
)
const (
data = `{
"A_key1": {
"B_key1": {
"C_key": "value"
}
}
}`
)
func BenchmarkB1(b *testing.B) {
b.ResetTimer()
for i := 0; i < b.N; i++ {
var p map[string]interface{}
json.Unmarshal([]byte(data), &p)
a1 := p["A_key1"]
a2 := p["A_key1"].(map[string]interface{})["B_key1"]
a3 := p["A_key1"].(map[string]interface{})["B_key1"].(map[string]interface{})["C_key"]
_ = a1 // --> map[B_key1:map[C_key:value]]
_ = a2 // --> map[C_key:value]
_ = a3 // --> value
}
}
func BenchmarkB2(b *testing.B) {
b.ResetTimer()
for i := 0; i < b.N; i++ {
var p map[string]interface{}
json.Unmarshal([]byte(data), &p)
b1 := p["A_key1"]
temp, _ := json.Marshal(b1)
json.Unmarshal(temp, &p)
b2 := p["B_key1"]
temp, _ = json.Marshal(b2)
json.Unmarshal(temp, &p)
b3 := p["C_key"]
_ = b1 // --> map[B_key1:map[C_key:value]]
_ = b2 // --> map[C_key:value]
_ = b3 // --> value
}
}
Result :
$ go test -bench .
BenchmarkB1-4 300000 4177 ns/op
BenchmarkB2-4 100000 13619 ns/op
PASS
It was found that the process cost of json.Unmarshal() was high. json.Unmarshal() for test 2 is 3 times larger than that for test 1.