两种方法，第一种：
package main

import (
"fmt"
"sync"
)

func main() {
var wg sync.WaitGroup
initial := make(chan struct{})
ch := make(chan int)
prev := initial
for i := 1; i <= 100; i++ {
wg.Add(1)
next := make(chan struct{})
go func(i int, prev, next chan struct{}) {
<-prev
ch <- i
close(prev)
if i < 100 {
next <- struct{}{}
}
}(i, prev, next)
prev = next
}

initial <- struct{}{}
go func() {
for i := range ch {
wg.Done()
fmt.Println(i)
}
}()

wg.Wait()
}

第二种（使用锁）：
package main

import (
"fmt"
"sync"
)

func main() {
var wg sync.WaitGroup
var mu sync.Mutex
ch := make(chan int)
cond := sync.NewCond(&mu)
current := 1

for i := 1; i <= 100; i++ {
wg.Add(1)
go func(num int) {
mu.Lock()
for current != num {
cond.Wait()
}
ch <- i
current++
cond.Broadcast()
mu.Unlock()
}(i)
}

go func() {
for i := range ch {
wg.Done()
fmt.Println(i)
}
}()

wg.Wait()
}