Go limited worker count

limited-concurrency.go

package main

import (
	"fmt"
	"runtime"
	"sync"
)

func doStuff(wg *sync.WaitGroup, guard chan struct{}, id int) {
	defer func() {
		wg.Done()
		<-guard
	}()
	fmt.Printf("from goroutine %d", id)
}

func main() {
  workload := []int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16}
	guard := make(chan struct{}, runtime.GOMAXPROCS(0))
	wg := &sync.WaitGroup{}
	for _, id := range workload {
		guard <- struct{}{} // would block if guard channel is already filled
		wg.Add(1)
		go doStuff(wg, guard, id)
	}

	wg.Wait()
}