pool

gistfile1.go

package main

import (
	"sync"
	"fmt"
)

func WorkerPool(size int) chan func() {
	listen := make(chan func())
	pool := make(chan bool, size)
	for i := 0; i < size; i++ {
		pool <- true
	}
	go func() {
		for {
			fun := <-listen
			go func() {
				<-pool
				defer func() {
					pool <- true
				}()
				fun()
			}()
		}
	}()
	return listen
}

func main() {
	workers := WorkerPool(8)
	n := 500000
	collect := make(map[int]bool)
	wait := new(sync.WaitGroup)
	for i := 0; i < n; i++ {
		wait.Add(1)
		argchan := make(chan int)
		workers <- func() {
			defer wait.Done()
			arg := <-argchan
			collect[arg] = true
		}
		argchan <- i
	}
	wait.Wait()
	fmt.Printf("%d\n", len(collect))
}