Gin + Golang + DB Connection Pooling - mysql

Question

I would like to understand how does GIN ensures that each HTTP request gets a unique DB ( say MySQL ) connection. Here is one example code.
If you see, since 'db' is a global object and therefore, the API router.GET("/person/:age"... gets access to DB.
Now with load, I suppose GIN will have concurrency implemented internally. If yes, then how does it ensures that each request gets a different connection. If no, then it is single threaded imnplementation. Could anyone please correct my understanding.
package main
import (
// "bytes"
"database/sql"
"fmt"
"github.com/gin-gonic/gin"
_ "github.com/go-sql-driver/mysql"
"net/http"
)
func checkErr(err error) {
if err != nil {
panic(err)
} else {
fmt.Println("successful...")
}
}
func main() {
db, err := sql.Open("mysql", "abfl:abfl#tcp(127.0.0.1:3306)/abfl?charset=utf8")
checkErr(err)
defer db.Close()
// make sure connection is available
err = db.Ping()
checkErr(err)
type User struct {
age int
name string
}
router := gin.Default()
// Add API handlers here
// GET a user detail
router.GET("/person/:age", func(c *gin.Context) {
var (
user User
result gin.H
)
age := c.Param("age")
fmt.Println("input age : '%d'", age)
row := db.QueryRow("select age, name from user where age = ?", age)
err = row.Scan(&user.age, &user.name)
fmt.Printf("user : %+v\n", user)
if err != nil {
// If no results send null
result = gin.H{
"user": nil,
"count": 0,
}
} else {
result = gin.H{
"age": user.age,
"name": user.name,
"count": 1,
}
}
c.JSON(http.StatusOK, result)
})
router.Run(":3000")
}

Answer 1

Establishing a new SQL connection for each HTTP request is too heavy and has no sense.
In go there is no user-managable connection pool yet, it is handled internally by go implementation.
sql.DB is ready to be used concurrently, so there is no worry about it.
And GIN has nothing to do with SQL connections at all. It is fully your responsibility to handle queries/transactions properly.