GO 语言：致命错误：所有 goroutine 都处于Hibernate 状态 死锁

下面的代码可以很好地处理硬编码的JSON数据，但是当我从文件中读取JSON数据时就不行了.当我使用sync.WaitGroup时，我得到了fatal error: all goroutines are asleep - deadlock个错误.

WORKING EXAMPLE WITH HARD-CODED JSON DATA:个

package main

import (
    "bytes"
    "fmt"
    "os/exec"
    "time"
)

func connect(host string) {
    cmd := exec.Command("ssh", host, "uptime")
    var out bytes.Buffer
    cmd.Stdout = &out
    err := cmd.Run()
    if err != nil {
        fmt.Println(err)
    }
    fmt.Printf("%s: %q\n", host, out.String())
    time.Sleep(time.Second * 2)
    fmt.Printf("%s: DONE\n", host)
}

func listener(c chan string) {
    for {
        host := <-c
        go connect(host)
    }
}

func main() {
    hosts := [2]string{"user1@111.79.154.111", "user2@111.79.190.222"}
    var c chan string = make(chan string)
    go listener(c)

    for i := 0; i < len(hosts); i++ {
        c <- hosts[i]
    }
    var input string
    fmt.Scanln(&input)
}

OUTPUT:

user@user-VirtualBox:~/go$ go run channel.go
user1@111.79.154.111: " 09:46:40 up 86 days, 18:16,  0 users,  load average: 5"
user2@111.79.190.222: " 09:46:40 up 86 days, 17:27,  1 user,  load average: 9"
user1@111.79.154.111: DONE
user2@111.79.190.222: DONE

NOT WORKING - EXAMPLE WITH READING JSON DATA FILE:

package main

import (
    "bytes"
    "fmt"
    "os/exec"
    "time"
    "encoding/json"
    "os"
    "sync"
)

func connect(host string) {
    cmd := exec.Command("ssh", host, "uptime")
    var out bytes.Buffer
    cmd.Stdout = &out
    err := cmd.Run()
    if err != nil {
        fmt.Println(err)
    }
    fmt.Printf("%s: %q\n", host, out.String())
    time.Sleep(time.Second * 2)
    fmt.Printf("%s: DONE\n", host)
}

func listener(c chan string) {
    for {
        host := <-c
        go connect(host)
    }
}

type Content struct {
    Username string `json:"username"`
    Ip       string `json:"ip"`
}

func main() {
    var wg sync.WaitGroup

    var source []Content
    var hosts []string
    data := json.NewDecoder(os.Stdin)
    data.Decode(&source)

    for _, value := range source {
        hosts = append(hosts, value.Username + "@" + value.Ip)
    }

    var c chan string = make(chan string)
    go listener(c)

    for i := 0; i < len(hosts); i++ {
        wg.Add(1)
        c <- hosts[i]
        defer wg.Done()
    }

    var input string
    fmt.Scanln(&input)

    wg.Wait()
}

OUTPUT

user@user-VirtualBox:~/go$ go run deploy.go < hosts.txt 
user1@111.79.154.111: " 09:46:40 up 86 days, 18:16,  0 users,  load average: 5"
user2@111.79.190.222: " 09:46:40 up 86 days, 17:27,  1 user,  load average: 9"
user1@111.79.154.111 : DONE
user2@111.79.190.222: DONE
fatal error: all goroutines are asleep - deadlock!

goroutine 1 [semacquire]:
sync.runtime_Semacquire(0xc210000068)
    /usr/lib/go/src/pkg/runtime/sema.goc:199 +0x30
sync.(*WaitGroup).Wait(0xc210047020)
    /usr/lib/go/src/pkg/sync/waitgroup.go:127 +0x14b
main.main()
    /home/user/go/deploy.go:64 +0x45a

goroutine 3 [chan receive]:
main.listener(0xc210038060)
    /home/user/go/deploy.go:28 +0x30
created by main.main
    /home/user/go/deploy.go:53 +0x30b
exit status 2
user@user-VirtualBox:~/go$

HOSTS.TXT

[
   {
      "username":"user1",
      "ip":"111.79.154.111"
   },
   {
      "username":"user2",
      "ip":"111.79.190.222"
   }
]