gorm: too many connections issue ?

I’m developing rest api with gin-gonic and I’m getting too many connections error. How to handle it ?

I’m on digital ocean 1GB RAM / 1CPU with mysql 5.7.9

my implementation

type Impl struct {
    DB gorm.DB
}

var i Impl

func main() {
    gin.SetMode(gin.ReleaseMode)
    r := gin.New()
    r.Use(gin.Logger())
    r.Use(gin.Recovery())

    i.InitDB()

    r.GET("/questions", func(c *gin.Context) {
        questions := i.GetRandomQuestions("userID", 10)
        c.JSON(200, gin.H{"question": questions})
    })


    r.Run(":" + os.Getenv("PORT"))
}

func (i *Impl) InitDB() {
    var err error
    i.DB, err = gorm.Open("mysql", "conn str")
    if err != nil {
        log.Fatalf("Got error when connect database, the error is '%v'", err)
    }
    i.DB.LogMode(true)
    i.DB.DB().SetMaxIdleConns(10)
    i.DB.DB().SetMaxOpenConns(100)
}

func (i *Impl) GetRandomQuestions(userID string, count int) []Question {
    var waitGroup sync.WaitGroup
    waitGroup.Add(count)
    questions := make([]Question, count)
    items := make([]Item, count)
    i.DB.Where("user_id = ? AND is_answered = ? AND RAND()<(SELECT ((?/COUNT(*))*10) FROM items)", userID, false, count).Order("RAND()").Limit(count).Find(&items)
    for index, item := range items {
        go func(item Item, index int) {
            defer waitGroup.Done()
            questions[index].Text = item
        }(item, index)
    }
    waitGroup.Wait()
    return questions
}