func main() {
	cfg := &config{}
	cfg.parse()
	connStr := cfg.db + "?maxAllowedPacket=512000000&charset=utf8mb4&parseTime=True&loc=Local&allowAllFiles=true"
	var wg sync.WaitGroup
	for i := 0; i < 100; i++ {
		wg.Add(1)
		go func() {
			db, err := sql.Open("mysql", connStr)
			if err != nil {
				log.Fatal(err)
			}
			defer db.Close()

			stmt, err := db.Prepare("select t.i, t.j from t, t1 where t.k = 0")
			if err != nil {
				log.Fatal(err)
			}

			stmt1, err := db.Prepare("select t.i, t.j from t, t1 where t.i = 0")
			if err != nil {
				log.Fatal(err)
			}

			for {
				rs, err := stmt.Query()
				if err != nil {
					log.Println(err)
					break
				}
				for rs.Next() {
					var i int
					var j int
					err = rs.Scan(&i, &j)
					if err != nil {
						log.Println(err)
						break
					}
					log.Println(i, j)
				}
				rs.Close()

				rs1, err := stmt1.Query()
				if err != nil {
					log.Println(err)
					break
				}
				for rs1.Next() {
					var i int
					var j int
					err = rs1.Scan(&i, &j)
					if err != nil {
						log.Println(err)
						break
					}
					log.Println(i, j)
				}
				rs1.Close()
			}
			wg.Done()
		}()
	}
	wg.Wait()
}