golang select和缓冲channel一起使用时如何保证安全退出，不丢失数据？

package main

import (
	"fmt"
	"sync"
	"time"
)

var (
	wg      sync.WaitGroup
	channel = make(chan int, 10)
)

func main() {
	//先写满一个channel
	for i := 0; i < 10; i++ {
		channel <- i
	}

	wg.Add(1)
	go func() {
		defer wg.Done()
		for {
			select {
			case num := <-channel:
				
				fmt.Println("======", num)
				//每次从channel取值后sleep 1秒，方便我们分析
				time.Sleep(time.Duration(num) * time.Second)

			}
		}
	}()
	wg.Wait()
}

package main

import (
	"fmt"
	"log"
	"os"
	"os/signal"
	"sync"
	"syscall"
	"time"
)

var (
	wg      sync.WaitGroup
	channel = make(chan int, 10000)
)

func main() {
	//先写满一个channel
	for i := 0; i < 10; i++ {
		channel <- i
	}
	wg.Add(1)
	go HandleSignals()
	wg.Add(1)
	go func() {
		defer wg.Done()
		for {
			select {
			case num, ok := <-channel:
				if !ok {
					return
				}
				fmt.Println("======", num)
				//每次从channel取值后sleep 1秒，方便我们分析
				time.Sleep(time.Duration(num) * time.Second)


			}
		}
	}()
	wg.Wait()
}
func HandleSignals() {
	defer wg.Done()

	ch := make(chan os.Signal, 10)
	signal.Notify(ch, syscall.SIGINT, syscall.SIGTERM, syscall.SIGUSR2)
	for {
		sig := <-ch
		switch sig {
		case syscall.SIGINT, syscall.SIGTERM:
			close(channel)
			log.Println("Exiting, please wait...")
			return
		}
	}
}

func closechan(c *hchan) {
    ...
    lock(&c.lock)
    if c.closed != 0 {
        unlock(&c.lock)
        panic(plainError("close of closed channel"))
    }
    ...

    c.closed = 1

    var glist gList

    // release all readers
    for {
        sg := c.recvq.dequeue()
        if sg == nil {
            break
        }
        if sg.elem != nil {
            typedmemclr(c.elemtype, sg.elem)
            sg.elem = nil
        }
        if sg.releasetime != 0 {
            sg.releasetime = cputicks()
        }
        gp := sg.g
        gp.param = nil
        if raceenabled {
            raceacquireg(gp, c.raceaddr())
        }
        glist.push(gp)
    }
    ...
}