Go by Example: Worker Pools
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In this example we’ll look at how to implement a worker pool using goroutines and channels. |
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package main
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import "fmt"
import "time"
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Here’s the worker, of which we’ll run several
concurrent instances. These workers will receive
work on the |
func worker(id int, jobs <-chan int, results chan<- int) {
for j := range jobs {
fmt.Println("worker", id, "processing job", j)
time.Sleep(time.Second)
results <- j * 2
}
}
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func main() {
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In order to use our pool of workers we need to send them work and collect their results. We make 2 channels for this. |
jobs := make(chan int, 100)
results := make(chan int, 100)
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This starts up 3 workers, initially blocked because there are no jobs yet. |
for w := 1; w <= 3; w++ {
go worker(w, jobs, results)
}
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Here we send 9 |
for j := 1; j <= 9; j++ {
jobs <- j
}
close(jobs)
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Finally we collect all the results of the work. |
for a := 1; a <= 9; a++ {
<-results
}
}
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Our running program shows the 9 jobs being executed by various workers. The program only takes about 3 seconds despite doing about 9 seconds of total work because there are 3 workers operating concurrently. |
$ time go run worker-pools.go
worker 1 processing job 1
worker 2 processing job 2
worker 3 processing job 3
worker 1 processing job 4
worker 2 processing job 5
worker 3 processing job 6
worker 1 processing job 7
worker 2 processing job 8
worker 3 processing job 9
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real 0m3.149s
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