How to solve TIME_WAIT state issue when in multiple concurrency?

If I run below example on Windows I will quickly hit TCP connection limit (which I set to 64k) and get error: dial tcp 127.0.0.1:3306: connectex: Only one usage of each socket address (protocol/network address/port) is normally permitted.

I see all this TIME_WAIT states waiting for there lifetime to end with: netstat -ano|findstr 3306

Why aren't connections closed immediately?

The code:

package main
import (
	_ "github.com/go-sql-driver/mysql"
	"github.com/jmoiron/sqlx"
	"log"
	"sync"
)
var (
	db_instance *sqlx.DB
	wg          sync.WaitGroup
)
func main() {
	db, err := sqlx.Connect("mysql", "user:pass@/table")
	if err != nil {
		log.Fatalln(err)
	}
	defer db.Close()
	db_instance = db
	for {
		for l := 0; l < 50; l++ {
			wg.Add(1)
			go DB_TEST()
		}
		wg.Wait()
	}
}
func DB_TEST() {
	defer wg.Done()
	var s string
	err := db_instance.QueryRow("SELECT NOW()").Scan(&s)
	if err != nil {
		log.Println(err)
		return
	}
	log.Println(s)
}

Drafting answer from my comments discussion with @Glavić.

Utilize the SetMaxOpenConns and SetMaxIdleConns settings to keep TIME_WAIT status and connections under control. If needed use SetConnMaxLifetime too, generally it's not needed.