I have a simple 2 file go application. I am trying to benchmark ping and pong messages on 2 channels.
The goal is to run the benchmark to see how many back and forth ping and pong can be done (that is why I am passing the attempts so the benchmark can keep running at different inputs)
For some reason locally it is only displaying this when I run it:
go build
./main
Output:
ping
pong
ping
pong
ping
pong
ping
pong
ping
Why does it end after so little iterations?
main.go
package main
import (
"fmt"
)
func main() {
PingPong(1000)
var input string
fmt.Scanln(input)
fmt.Println("done!")
}
ping.go
package main
import "fmt"
func PingPong(attempts int) {
pingCh := make(chan string)
pongCh := make(chan string)
go pinger(pingCh, pongCh)
go ponger(pingCh, pongCh, attempts)
pingCh <- "ping"
}
func pinger(pingCh chan string, pongCh chan string) {
for {
_ = <-pingCh
fmt.Println("ping")
pongCh <- "pong"
}
}
func ponger(pingCh chan string, pongCh chan string, attempts int) {
counter := 0
for {
msg := <-pongCh
fmt.Println(msg)
counter++
if counter == attempts {
fmt.Println(counter)
break
}
pingCh <- "ping"
}
}
ping_test.go
package main
import "testing"
func benchmarkPingPong(i int, b *testing.B) {
for n := 0; n < b.N; n++ {
PingPong(n)
}
}
fmt.Scanln needs a pointer:
Use this:
fmt.Println(fmt.Scanln(&input))
This works for me:
package main
import "fmt"
func main() {
PingPong(1000)
var input string
fmt.Println(fmt.Scanln(&input))
fmt.Println("done!")
}
func PingPong(attempts int) {
pingCh := make(chan string)
pongCh := make(chan string)
go pinger(pingCh, pongCh)
go ponger(pingCh, pongCh, attempts)
pingCh <- "ping"
}
func pinger(pingCh chan string, pongCh chan string) {
for {
_ = <-pingCh
fmt.Println("ping")
pongCh <- "pong"
}
}
func ponger(pingCh chan string, pongCh chan string, attempts int) {
counter := 0
for {
msg := <-pongCh
counter++
fmt.Println(msg, counter)
if counter == attempts {
fmt.Println(counter)
break
}
pingCh <- "ping"
}
}
output:
...
ping
pong 999
ping
pong 1000
1000
The reason it wasn't working is that I moved the files out from main.go to ping.go. When I ran go build, it created different binary name ./pingpong but I was still running the old binary!