Deadlock while sending data to channel in slice of channels

Sending data to integer channel in slice of channels is resulting into deadlock

The code is expected to create 5 (+1 fanInChan) channels. These channels are used for send integer values through send() and receive the same in receive() and finally Fan-in the them to fanInChan.

Code:-

package main

import (
	"fmt"
	"sync"
)

func main() {
	defer fmt.Println("About to exit!")
	fmt.Println("Started")

	channels := make([]chan int, 5)
	fanInChan := make(chan int)

	go send(channels)
	go recive(fanInChan, channels)

	for val := range fanInChan {
		fmt.Println("Fanin", val)
	}
}
func send(channels []chan int) {
	defer fmt.Println("Send Ended")
	fmt.Println("Send Started")

	for i := 0; i < 100; i++ {
		channels[i%5] <- i
	}

	for i := 0; i < 5; i++ {
		close(channels[i])
	}
}

func recive(fanin chan<- int, channels []chan int) {
	defer fmt.Println("Recive Ended")
	fmt.Println("Recive Started")

	var wg sync.WaitGroup
	wg.Add(5)

	for i := 0; i < 5; i++ {
		go func(inew int) {
			defer wg.Done()
			fmt.Println(inew)
			for v := range channels[inew] {
				fanin <- v
			}
		}(i)
	}

	wg.Wait()
	close(fanin)
}

Golang PlayGround

OutPut:-

Started
Send Started
Recive Started
4
1
2
3
0
fatal error: all goroutines are asleep - deadlock!
... //You can see rest on playground link above

Problem is starting in a for loop inside send()

for i := 0; i < 100; i++ {
channels[i%5] <- i
}

The statement channels := make([]chan int, 5) is allocating a array with nil channels which

• Blocks receiving <- channel from channel
• Blocks sending channel <- value into channel
• panics on closing close(channel)

So you have to initialize each channel individually to recive integer values.

You should init the channels in the channels array before using those.

    for i := range channels {
channels[i] = make(chan int)
}

Insert this just before the line go send(channels) and run.