go max concurrent example

main.go

//https://goplay.tools/snippet/gYQ3zCEsjUV
package main

import (
	"fmt"
	"time"
)

func main() {
	batch := 5
	waits := []int{10, 23, 11, 15, 16, 13, 19, 12, 10, 22, 12}
	errChan := make(chan error)
	done := make(chan struct{})
	fmt.Printf("wait times: %#v\n", waits)
	go func() {
		for i, w := range waits {
			if i >= batch {
				<-errChan
			}
			go foo(w, errChan)
		}
		done <- struct{}{}
	}()
	<-done
}

func foo(i int, errChan chan error) {
	fmt.Printf("starting %d\n", i)
	time.Sleep(time.Duration(i) * time.Second)
	fmt.Printf("running completed %d\n", i)
	errChan <- nil
}