JSON unmarshal serial v. parallel

main_test.go

package main

import (
    "encoding/json"
    "sync"
    "testing"
)

var jsonStr = `{"url":"http://hoge","score":123,"map":{"123":123,"234":234}}`

type Map map[string]int

type Source struct {
    URL   string `json:"url"`
    Score int    `json:"score"`
    Map   Map    `json:"map"`
}

func BenchmarkSerial_JSON_Unmarshal(b *testing.B) {
    jsonBytes := []byte(jsonStr)

    b.ResetTimer()
    for i := 0; i < b.N; i++ {
        var src Source
        json.Unmarshal(jsonBytes, &src)
    }
    b.StopTimer()
}

func BenchmarkParallel_JSON_Unmarshal(b *testing.B) {
    jsonBytes := []byte(jsonStr)

    var wg sync.WaitGroup
    out := make(chan []byte)

    wg.Add(5)
    for i := 0; i < 5; i++ {
        go func(w *sync.WaitGroup, in <-chan []byte) {
            defer w.Done()
            for input := range in {
                var src Source
                json.Unmarshal(input, &src)
            }
        }(&wg, out)
    }

    b.ResetTimer()
    for i := 0; i < b.N; i++ {
        out <- jsonBytes
    }
    b.StopTimer()

    close(out)
    wg.Wait()
}

/**
BenchmarkSerial_JSON_Unmarshal-4          300000              4265 ns/op
BenchmarkParallel_JSON_Unmarshal-4        500000              3024 ns/op
 */

% cat /proc/cpuinfo | grep ^processor | wc -l
4