simple-golang-pool-example.go

package main

import (
        "fmt"
        "time"
        "sync"
)

func work(serverChan chan int, wg *sync.WaitGroup, server int, thing string) {
        defer wg.Done()

        // processing
        time.Sleep(time.Duration(server) * time.Second)

        now := time.Now()
        fmt.Printf("%v, use server: %d, do thing: %s \n", now, server, thing)
        serverChan <- server
}

func main() {
        serverCount := 4
        serverChan := make(chan int, thingCount)
        for i := 1; i <= serverCount; i++ {
                serverChan <- i
        }

        thingCount := 10
        for i := 1; i <= thingCount;  i++ {
                wg.Add(1)
                go work(serverChan, &wg, <- serverChan, fmt.Sprintf("thing %d", i))
        }

        wg.Wait()
}