如何解决多并发时的TIME_WAIT状态问题？

Question

如果我在Windows上运行下面的例子，我将很快达到TCP连接限制(我设置为64k)并得到错误：dial tcp 127.0.0.1:3306: connectex: Only one usage of each socket address (protocol/network address/port) is normally permitted.

我看到所有这些等待生命周期结束的TIME_WAIT状态都是：netstat -ano|findstr 3306

为什么不立即关闭连接？

代码：

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)
}