使用fanIn功能多路复用Go常规输出

I was trying to implement an example Go code for using returned channels from go routines without any "reading block" in the main function. Here, a fanIn function accepts channels from two other routines and return which got as input.

Here, the expected output is Random Outputs from two inner routines. But the actual output is always one "ann" followed by a "john", not at all random in any case.

Why am I not getting random output?

Go Playground: http://play.golang.org/p/46CiihtPwD

Actual output:

  you say: ann,0 
  you say: john,0
  you say: ann,1
  you say: john,1 
   ......

Code:

package main

import (
    "fmt"
    "time"
)

func main() {

    final := fanIn(boring("ann"), boring("john"))

    for i := 0; i < 100; i++ {
        fmt.Println("you say:", <-final)

    }
    time.Sleep(4 * time.Second)
}

func boring(msg string) chan string {
    c1 := make(chan string)
    go func() {
        for i := 0; ; i++ {
            c1 <- fmt.Sprintf("%s,%d", msg, i)
            time.Sleep(time.Second)

        }
    }()
    return c1
}

func fanIn(input1, input2 <-chan string) chan string {
    c := make(chan string)
    go func() {
        for {
            c <- <-input1
        }
    }()
    go func() {
        for {
            c <- <-input2
        }
    }()
    return c
}

No particular reason, that's just how Go happens to schedule the relevant goroutines (basically, you're getting "lucky" that there's a pattern). You can't rely on it. If you really want an actual reliably random result, you'll have to manually mix in randomness somehow.

There's also the Multiplex function from https://github.com/eapache/channels/ (doc: https://godoc.org/github.com/eapache/channels#Multiplex) which does effectively the same thing as your fanIn function. I don't think it would behave any differently in terms of randomness though.