How to run multiple goroutines in parallel?

Question

go

I can't get this code to work in parallel.
Who knows what I'm doing wrong?

package main

import (
  "fmt"
  "time"
)

func main() {
  t1 := time.Now()
  s1 := make(chan int)
  s2 := make(chan int)
  s3 := make(chan int)

  go summ1(s1)
  go summ2(s2)
  go summ3(s3)

  r1 := <-s1
  r2 := <-s2
  r3 := <-s3

  fmt.Println(r1)
  fmt.Println(r2)
  fmt.Println(r3)

  fmt.Println("elapsedTime:", time.Now().Sub(t1))
}

func summ1(summ chan int) {
  var sum int
  for i := 0; i < 1000000000; i++ {
    sum += i
  }
  summ <- sum
}

func summ2(summ chan int) {
  var sum int
  for i := 0; i < 1000000001; i++ {
    sum += i
  }
  summ <- sum
}

func summ3(summ chan int) {
  var sum int
  for i := 0; i < 1000000002; i++ {
    sum += i
  }
  summ <- sum
}

Answer 1

"The number of running Machines is limited by the GOMAXPROCS environment variable or the runtime.GOMAXPROCS(n int) function. It defaults to 1. It usually makes sense to set it to the number of cores."
One machine - one goroutine.
https://habr.com/ru/post/141853/