go 46 lines · 7 steps

A graceful worker pool in Go

A worker pool that processes jobs from a channel and shuts every goroutine down cleanly with a broadcast signal.

Explained by highlit
Intermediate concurrency goroutines channels graceful-shutdown synchronization
1package worker
2 
3import (
4 "fmt"
5 "sync"
6 "time"
7)
8 
9type Pool struct {
10 done chan struct{}
11 once sync.Once
12 wg sync.WaitGroup
13}
14 
15func NewPool() *Pool {
16 return &Pool{done: make(chan struct{})}
17}
18 
19func (p *Pool) Spawn(id int, jobs <-chan string) {
20 p.wg.Add(1)
21 go func() {
22 defer p.wg.Done()
23 for {
24 select {
25 case <-p.done:
26 fmt.Printf("worker %d: shutting down\n", id)
27 return
28 case job, ok := <-jobs:
29 if !ok {
30 return
31 }
32 select {
33 case <-p.done:
34 return
35 case <-time.After(50 * time.Millisecond):
36 fmt.Printf("worker %d: processed %s\n", id, job)
37 }
38 }
39 }
40 }()
41}
42 
43func (p *Pool) Shutdown() {
44 p.once.Do(func() { close(p.done) })
45 p.wg.Wait()
46}
01 / 01
STEP 01

Walkthrough

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Three takeaways
  1. 1Closing a channel broadcasts to every receiver at once, which makes it the idiomatic Go shutdown signal.
  2. 2A sync.Once guards close so Shutdown is safe to call repeatedly without panicking on a double close.
  3. 3Pairing a WaitGroup with the done channel lets shutdown both signal and block until all workers actually exit.

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