| To wait for multiple goroutines to finish, we can use a *wait group*. | ||
package main |
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import ( |
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"fmt" |
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"sync" |
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"time" |
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) |
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| This is the function we'll run in every goroutine. Note that a WaitGroup must be passed to functions by pointer. | func worker(id int, wg *sync.WaitGroup) { |
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| On return, notify the WaitGroup that we're done. | defer wg.Done() |
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fmt.Printf("Worker %d starting\n", id) |
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| Sleep to simulate an expensive task. | time.Sleep(time.Second) |
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fmt.Printf("Worker %d done\n", id) |
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} |
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func main() { |
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| This WaitGroup is used to wait for all the goroutines launched here to finish. | var wg sync.WaitGroup |
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| Launch several goroutines and increment the WaitGroup counter for each. | for i := 1; i <= 5; i++ { |
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wg.Add(1) |
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go worker(i, &wg) |
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} |
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| Block until the WaitGroup counter goes back to 0; all the workers notified they're done. | wg.Wait() |
Worker 5 starting Worker 1 starting Worker 3 starting Worker 2 starting Worker 4 starting Worker 5 done Worker 4 done Worker 1 done Worker 3 done Worker 2 done |
} |