Go工作池实例

在这个例子中，我们将看看如何使用goroutines和channel实现一个工作池。

这里是工作程序(worker)，我们将运行几个并发实例。这些工作程序(worker)将在工作渠道上接收工作，并将结果发送相应的结果。将每个工作程序(worker)睡一秒钟，用来模拟执行的任务。

为了使用工作程序(worker)池，需要向它们发送工作(或作业)并收集的结果。为此做2个通道。

这启动了3个工作程序(worker)，最初被阻止，因为还没有作业。

然后，我们再发送5个作业，然后关闭该通道，以指示这是所有的工作。

最后，收集作业的所有结果。

运行程序显示了5个作业正在由各种工作程序执行。该程序只需要约2秒的时间，尽管做了大约5秒的总工作，因为有3个工作程序同时操作。

所有的示例代码，都放在 F:\worksp\golang 目录下。安装Go编程环境请参考：/tutorial/detail-5562.html

timers.go的完整代码如下所示 -

package main

import "fmt"
import "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.
    jobs := make(chan int, 100)
    results := make(chan int, 100)

    // 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 <= 5; j++ {
        jobs <- j
    }
    close(jobs)

    // Finally we collect all the results of the work.
    for a := 1; a <= 5; a++ {
        <-results
    }
}

执行上面代码，将得到以下输出结果 -

F:\worksp\golang>go run worker-pools.go
worker 3 started  job 2
worker 1 started  job 1
worker 2 started  job 3
worker 3 finished job 2
worker 3 started  job 4
worker 1 finished job 1
worker 1 started  job 5
worker 2 finished job 3
worker 3 finished job 4
worker 1 finished job 5