使用协程扫描端口时，主协程提前退出怎么办？

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

func scanPort(jobChan <-chan int, retChan chan<- string, wg *sync.WaitGroup) {
    defer wg.Done()
    for port := range jobChan {
        target := fmt.Sprintf("149.129.68.235:%d", port)
        _, err := net.DialTimeout("tcp", target, 100*time.Millisecond)
        if err == nil {
            retChan <- fmt.Sprintf("%s is open", target)
        }
    }
}

func main() {
    jobChan := make(chan int, 5)
    retChan := make(chan string, 5)
    var wg sync.WaitGroup

    go func() {
        for i := 0; i < 1024; i++ {
            jobChan <- i
        }
        close(jobChan)
    }()

    for i := 0; i < 10; i++ {
        wg.Add(1)
        go scanPort(jobChan, retChan, &wg)
    }

    go func() {
        for ret := range retChan {
            fmt.Println(ret)
        }
    }()

    wg.Wait()
    close(retChan)
}