main.go

package main

import (
	"database/sql"
	"flag"
	"log"
	"time"

	_ "github.com/lib/pq"
)

func main() {
	db, err := sql.Open("postgres", "user=postgres host=127.0.0.1 dbname=benchmark sslmode=disable")
	if err != nil {
		log.Fatal(err)
	}

	err = db.Ping()
	if err != nil {
		log.Fatal(err)
	}

	done := make(chan bool)

	nPtr := flag.Int("n", 10, "number of goroutines")
	flag.Parse()
	n := *nPtr

	for i := 0; i < n; i++ {
		go func() {
			start := time.Now()
			read(db)
			log.Println(time.Since(start))
			done <- true
		}()
	}

	for i := 0; i < n; i++ {
		<-done
	}

	db.Close()
}

func read(db *sql.DB) {
	rows, err := db.Query("SELECT name FROM users")
	if err != nil {
		log.Fatal(err)
	}
	defer rows.Close()

	users := []user{}
	for rows.Next() {
		user := user{}
		err := rows.Scan(
			&user.Name,
		)
		if err != nil {
			log.Fatal(err)
		}
		users = append(users, user)
	}
}

type user struct {
	Name string `db:"name"`
}