Limit number of goroutines

package main

import (
	"fmt"
	"runtime"
	"time"
)

func main() {
	maxGoroutines := 2
	guard := make(chan struct{}, maxGoroutines)

	for i := 0; i < 50; i++ {
		guard <- struct{}{}
		go func(n int) {
			worker(n)
			<-guard
		}(i)
	}
}

func worker(i int) {
	time.Sleep(time.Second * 10) // processing time for the task
	fmt.Println(runtime.NumGoroutine()) // print number or running current goroutines
	fmt.Println("doing work on", i)
}

package main

import (
	"fmt"
	"time"
)

const LIMIT = 25

func main() {
    sem := make(chan int, LIMIT)
    for {
        sem <- 1 // will block if there is LIMIT ints in sem
        go func() {
			time.Sleep(time.Second * 10) // processing time for the task
            fmt.Println("doing work")
            <-sem // removes an int from sem, allowing another to proceed
        }()
    }
}