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54 lines
1.3 KiB
Go
54 lines
1.3 KiB
Go
// In this example we'll look at how to implement
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// a _worker pool_ using goroutines and channels.
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package main
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import (
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"fmt"
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"time"
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)
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// Here's the worker, of which we'll run several
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// concurrent instances. These workers will receive
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// work on the `jobs` channel and send the corresponding
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// results on `results`. We'll sleep a second per job to
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// simulate an expensive task.
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func worker(id int, jobs <-chan int, results chan<- int) {
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for j := range jobs {
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fmt.Println("worker", id, "started job", j)
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time.Sleep(time.Second)
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fmt.Println("worker", id, "finished job", j)
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results <- j * 2
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}
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}
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func main() {
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// In order to use our pool of workers we need to send
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// them work and collect their results. We make 2
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// channels for this.
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jobs := make(chan int, 100)
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results := make(chan int, 100)
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// This starts up 3 workers, initially blocked
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// because there are no jobs yet.
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for w := 1; w <= 3; w++ {
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go worker(w, jobs, results)
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}
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// Here we send 5 `jobs` and then `close` that
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// channel to indicate that's all the work we have.
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for j := 1; j <= 5; j++ {
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jobs <- j
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}
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close(jobs)
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// Finally we collect all the results of the work.
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// This also ensures that the worker goroutines have
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// finished. An alternative way to wait for multiple
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// goroutines is to use a [WaitGroup](waitgroups).
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for a := 1; a <= 5; a++ {
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<-results
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}
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}
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