go 退出但是端口依然被占用的原因

package main

import (
    setting "bitian_go/pkg"
    "bitian_go/routers"
    "context"
    "log"
    "net/http"
    "os"
    "os/signal"
    "syscall"
    "time"
)

//var EsClient *elastic.Client

func init() {
    setting.Setup()
    setting.NewMysqlClient()
    setting.InitRedis()
    //EsClient = setting.NewEsClient()
}
func main() {

    r := routers.Router()
    srv := &http.Server{
        Addr:           ":8000",
        Handler:        r,
        ReadTimeout:    30 * time.Second,
        WriteTimeout:   30 * time.Second,
        MaxHeaderBytes: 1 << 20,
    }
    go func() {
        // 服务连接
        if err := srv.ListenAndServe(); err != nil && err != http.ErrServerClosed {
            log.Fatalf("listen: %s\n", err)
        }
    }()

    // 等待中断信号以优雅地关闭服务器（设置 5 秒的超时时间）
    quit := make(chan os.Signal)
    signal.Notify(quit, os.Interrupt, syscall.SIGQUIT, syscall.SIGHUP)
    <-quit
    log.Println("Shutdown Server ...")

    ctx, cancel := context.WithTimeout(context.Background(), 1*time.Second)
    defer cancel()
    if err := srv.Shutdown(ctx); err != nil {
        log.Fatal("Server Shutdown:", err)
    }
    log.Println("Server exiting")
}

现在通过hup 命令可以关闭go 程序，但是接口依然被占用，所以想知道问题在哪里。