Question

I want to write three concurrent routines that sends integer to each other. Now, I have implemented two concurrent routines which sends integers to each other.

package main
import "rand"

func Routine1(commands chan int, responses chan int) {
    for i := 0; i < 10; i++ {
        i := rand.Intn(100)
  commands <- i
  print(<-responses, " 1st\n");
}
close(commands)
}

func Routine2(commands chan int, responses chan int) {
for i := 0; i < 1000; i++ {
    x, open := <-commands
    if !open {
        return;
    }
     print(x , " 2nd\n");
    y := rand.Intn(100)
    responses <- y
}
}

func main() 
{
   commands := make(chan int)
   responses := make(chan int)
   go Routine1(commands, responses)
   Routine2(commands, responses)
}

However, when I want to add another routine which wants to send and receive integers to/from the above routines, it gives errors like “throw: all goroutines are asleep – deadlock!”. Below is my code:

package main
import "rand"

func Routine1(commands chan int, responses chan int, command chan int, response chan int ) {
for i := 0; i < 10; i++ {
    i := rand.Intn(100)
  commands <- i
  command <- i
  print(<-responses, " 12st\n");
  print(<-response, " 13st\n");
}
close(commands)
}

func Routine2(commands chan int, responses chan int) {
for i := 0; i < 1000; i++ {
    x, open := <-commands
    if !open {
        return;
    }
     print(x , " 2nd\n");
    y := rand.Intn(100)
    responses <- y
}
}

func Routine3(command chan int, response chan int) {
for i := 0; i < 1000; i++ {
    x, open := <-command
    if !open {
        return;
    }
     print(x , " 3nd\n");
    y := rand.Intn(100)
    response <- y
}
}

func main() {
   commands := make(chan int)
   responses := make(chan int)
   command := make(chan int)
   response := make(chan int)
   go Routine1(commands, responses,command, response )
   Routine2(commands, responses)
   Routine3(command, response)
}

Can anybody help me, where is my mistake ? And can anybody help me, is it possible to create bidirectional channel or is it possible to create a common channel for int, string etc ?

Answer 1

You haven’t declared the command and response variables in the main function.

func main() {
    commands := make(chan int)
    responses := make(chan int)
    go Routine1(commands, responses, command, response)
    Routine2(commands, responses)
    Routine3(command, response)
}