55 lines
1.4 KiB
Go
55 lines
1.4 KiB
Go
// In this example we'll look at how to implement
|
|
// a _worker pool_ using goroutines and channels.
|
|
|
|
package main
|
|
|
|
import (
|
|
"fmt"
|
|
"time"
|
|
)
|
|
|
|
// Here's the worker, of which we'll run several
|
|
// concurrent instances. These workers will receive
|
|
// work on the `jobs` channel and send the corresponding
|
|
// results on `results`. We'll sleep a second per job to
|
|
// simulate an expensive task.
|
|
func worker(id int, jobs <-chan int, results chan<- int) {
|
|
for j := range jobs {
|
|
fmt.Println("worker", id, "started job", j)
|
|
time.Sleep(time.Second)
|
|
fmt.Println("worker", id, "finished job", j)
|
|
results <- j * 2
|
|
}
|
|
}
|
|
|
|
func main() {
|
|
|
|
// In order to use our pool of workers we need to send
|
|
// them work and collect their results. We make 2
|
|
// channels for this.
|
|
const numJobs = 5
|
|
jobs := make(chan int, numJobs)
|
|
results := make(chan int, numJobs)
|
|
|
|
// This starts up 3 workers, initially blocked
|
|
// because there are no jobs yet.
|
|
for w := 1; w <= 3; w++ {
|
|
go worker(w, jobs, results)
|
|
}
|
|
|
|
// Here we send 5 `jobs` and then `close` that
|
|
// channel to indicate that's all the work we have.
|
|
for j := 1; j <= numJobs; j++ {
|
|
jobs <- j
|
|
}
|
|
close(jobs)
|
|
|
|
// Finally we collect all the results of the work.
|
|
// This also ensures that the worker goroutines have
|
|
// finished. An alternative way to wait for multiple
|
|
// goroutines is to use a [WaitGroup](waitgroups).
|
|
for a := 1; a <= numJobs; a++ {
|
|
<-results
|
|
}
|
|
}
|