1 package main
 2 
 3 import "fmt"
 4 import "time"
 5 
 6 // Here's the worker, of which we'll run several
 7 // concurrent instances. These workers will receive
 8 // work on the `jobs` channel and send the corresponding
 9 // results on `results`. We'll sleep a second per job to
10 // simulate an expensive task.
11 func worker(id int, jobs <-chan int, results chan<- int) {
12     for j := range jobs {
13         fmt.Println("worker", id, "started  job", j)
14         time.Sleep(time.Second)
15         fmt.Println("worker", id, "finished job", j)
16         results <- j * 2
17     }
18 }
19 
20 func main() {
21 
22     // In order to use our pool of workers we need to send
23     // them work and collect their results. We make 2
24     // channels for this.
25     jobs := make(chan int, 100)
26     results := make(chan int, 100)
27 
28     // This starts up 3 workers, initially blocked
29     // because there are no jobs yet.
30     for w := 1; w <= 3; w++ {
31         go worker(w, jobs, results)
32     }
33 
34     // Here we send 5 `jobs` and then `close` that
35     // channel to indicate that's all the work we have.
36     for j := 1; j <= 5; j++ {
37         jobs <- j
38     }
39     close(jobs)
40 
41     // Finally we collect all the results of the work.
42     for a := 1; a <= 5; a++ {
43         <-results
44     }
45 }

 1 worker 3 started  job 2
 2 worker 1 started  job 1
 3 worker 2 started  job 3
 4 worker 3 finished job 2
 5 worker 3 started  job 4
 6 worker 1 finished job 1
 7 worker 1 started  job 5
 8 worker 2 finished job 3
 9 worker 3 finished job 4
10 worker 1 finished job 5