Go lang multiplexing all goroutines are asleep - deadlock

I wants to create a fan-in function using multiple go routines returning channel here is my code.

package main

import (
	"fmt"
	"math/rand"
	"sync"
	"time"
)

var wg, wg2 sync.WaitGroup

func main() {
	final := talk(boring("Joe"), boring("Ann"))
	for i := 0; i < 10; i++ {
		fmt.Println(<-final)
	}
	fmt.Println("You are both boring I'm leaving")
}

func talk(input1, input2 <-chan string) <-chan string {
	out := make(chan string)
	go func() {
		wg.Add(1)
		for {
			out <- <-input1
		}
	}()
	go func() {
		wg.Add(1)
		for {
			out <- <-input2
		}
	}()
	wg.Done()
	close(out)
	return out
}

func boring(msg string) <-chan string {
	c := make(chan string)
	for i := 0; i < 5; i++ {
		c <- fmt.Sprintf("%s%d\n", msg, i)
		time.Sleep(time.Duration(rand.Intn(1e3)) * time.Millisecond)
	}
	return c
}

But I got an error after running above code

> all goroutines are asleep - deadlock

I have tried to close channels but still it is giving me the error. I have tried to assign boring returned channels to Joe and Ann and then pass those channels to talk function for multiplexing still no success. I am new to go learning channels not clear on this concept.

Instead of wait groups, you can use select: https://tour.golang.org/concurrency/5

> The select statement lets a goroutine wait on multiple communication
> operations.
>
> A select blocks until one of its cases can run, then it executes that
> case. It chooses one at random if multiple are ready.
>
>

package main

import (
	"fmt"
	"math/rand"
	"time"
)

func main() {
	final := talk(boring("Joe"), boring("Ann"))
	for i := 0; i < 10; i++ {
		fmt.Println(<-final)
	}
	fmt.Println("You are both boring I'm leaving")
}

func talk(input1, input2 <-chan string) <-chan string {
	c := make(chan string)
	go func() {
		for {
			select {
			case s := <-input1:
				c <- s
			case s := <-input2:
				c <- s
			}
		}
	}()
	return c
}

func boring(msg string) <-chan string {
	c := make(chan string)
	go func() {
		for i := 0; i < 5; i++ {
			c <- fmt.Sprintf("%s: %d", msg, i)
			time.Sleep(time.Duration(rand.Intn(1e3)) * time.Millisecond)
		}
	}()
	return c
}

Try it on Playground

Edit:

In your given example, boring function doesn't use goroutine for repeated send over channel which will block forever, because:
https://tour.golang.org/concurrency/2

> By default, sends and receives block until the other side is ready.
> This allows goroutines to synchronize without explicit locks or
> condition variables.

Also, wg.Done() needs to be part of goroutine.

I got it working by doing above changes: https://play.golang.org/p/YN0kfBO6iT

You cannot stop a goroutine by itself, I suggest signaling the goroutine to quit with something along these lines:

stop := make(chan bool)
go func() {
    for {
        select {
        case <- stop:
            return
        default:
            // Do other stuff
        }
    }
}()

// Do stuff

// Quit goroutine
stop<- true