I need to use 3 goroutines named g1, g2, g3. and distribute numbers from 1-10 among the above 3 goroutines in a round-robin fashion. They will do some hypothetical work based on the provided number. And program should print output in the following manner.
g1-1
g2-2
g3-3
g1-4
g2-5
g3-6
...
Tasks must be performed concurrently but the output must be in sequential order.
I have implemented the below code which distributes numbers and prints but output print order is not guaranteed as mentioned above.
I need some help to fix the below code or suggestions on another approach to get the above-desired output.
Approach 1:
package main
import (
"fmt"
"sync"
)
func main() {
chang1 := make(chan int)
chang2 := make(chan int)
chang3 := make(chan int)
var wg sync.WaitGroup
wg.Add(3)
go func() {
for num := range chang1 {
fmt.Println("g1", num)
}
wg.Done()
}()
go func() {
for num := range chang2 {
fmt.Println("g2", num)
}
wg.Done()
}()
go func() {
for num := range chang3 {
fmt.Println("g3", num)
}
wg.Done()
}()
channels := []chan int{chang1, chang2, chang3}
for i := 1; i <= 10; i++ {
currentCh := (i - 1) % 3
channels[currentCh] <- i
}
close(chang1)
close(chang2)
close(chang3)
wg.Wait()
}
output (with incorrect sequence)
g1- 1
g1- 4
g2- 2
g3- 3
g1- 7
g2- 5
g2- 8
g3- 6
g3- 9
g1- 10
...
if you don't want to use slice then I think something like this will work:- (playground)
package main
import (
"fmt"
)
func main() {
chang1 := make(chan string)
chang2 := make(chan string)
chang3 := make(chan string)
channels := []chan string{chang1, chang2, chang3}
for i := 1; i < 10; i += 3 {
go g1(i, channels[i%3])
go g2(i+1, channels[(i+1)%3])
go g3(i+2, channels[(i+2)%3])
fmt.Print(<-channels[i%3])
fmt.Print(<-channels[(i+1)%3])
fmt.Print(<-channels[(i+2)%3])
}
}
func g1(i int, chanel chan string) {
chanel <- fmt.Sprintln("g1", i)
}
func g2(i int, chanel chan string) {
chanel <- fmt.Sprintln("g2", i)
}
func g3(i int, chanel chan string) {
chanel <- fmt.Sprintln("g3", i)
}
output
g1 1
g2 2
g3 3
g1 4
g2 5
g3 6
g1 7
g2 8
g3 9
but keep in mind in this solution you have to run 3 goroutines then wait for all of them to give the result then go back
if this is not ok for you you need to use bufferd channels.