“ pq：抱歉，客户端太多”-使用Scan（），关闭行，但某处出现连接泄漏

My code is set up such that every time I want to make a query I open the DB, run QueryRow(), Scan the results into variables, and then close the DB and rows using defer. However, I'm getting a connection leak though I believe I've closing all of them out.

I have tried taking the close statements out of defer, closing them just when I am done using it. I followed How to reuse a single Postgres DB connection for row inserts in Go? but though I believe I'm following the answer, still no luck.

func (a AccessPostgres) OpenDB() (*sql.DB, error) {
    dbinfo := fmt.Sprintf("user=%s password=%s dbname=%s sslmode=disable",
                            user, password, a.DBName)

    var err error

    db, err := sql.Open("postgres", dbinfo)
    if err != nil {
        return nil, err
    }

    return db, nil
}

func (a AccessPostgres) Run(s string) error {
    db, err := a.OpenDB()
    if err != nil {
        return err
    }
    defer db.Close()

    _, err = db.Exec(s)
    if err != nil {
        return err
    }

    return nil
}

type Row struct {
    Collection_time string
    Dbid            string
    Hostname        string
    Dbname          string
    Name            string
    Value           string
}

type QueryResult struct {
    Rows  []Row
}

func (a AccessPostgres) Query(q string) ([]byte, error) {

    db, err := a.OpenDB()
    if err != nil {
        return nil, err
    }
    defer db.Close()

    rows, err := db.Query(q)
    if err != nil {
        return nil, err
    }
    defer rows.Close()

    var qr QueryResult
    for rows.Next() {
        var r Row
        err := rows.Scan(&r.Collection_time, &r.Dbid, &r.Hostname, &r.Dbname, &r.Name, &r.Value)
        if err != nil {
            return nil, err
        }
        qr.Rows = append(qr.Rows, r)
    }


    result, err := json.Marshal(qr)
    if err != nil {
        return nil, err
    }

    return result, nil
}

For the most part things work well. But this code is run at an interval and after awhile the 'pq: sorry, too many clients' error shows up. That's all that happens.