How to solve TIME_WAIT state issue when in multiple concurrency?

Question

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)
}

Answer 1

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.