我正在学习GOLANG，特别是它的并发能力。
尝试进一步开发其中一个worker_pool示例，以便每个worker接收一个作业ID和一个作业负载，以作业的随机持续时间表示。
time.sleep命令使用持续时间来等待分配的纳秒数，这是随机计算的。
代码看起来像这样......
//worker_pool improved example
package main
import "fmt"
import "time"
import "math/rand"
// 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 random number of seconds between
// 1 and 5 to simulate an expensive task.
func worker(id int, jobs <-chan int, loads <-chan time.Duration, results chan<- int) {
for j := range jobs {
fmt.Println("worker", id, "started job", j, time.Now())
time.Sleep(loads*time.Second)
fmt.Println("worker", id, "finished job", j, time.Now())
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)
loads := make(chan time.Duration)
results := make(chan int)
// 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 24 `jobs` and then `close` that
// channel to indicate that's all the work we have.
for j := 1; j <= 24; j++ {
jobs <- j
r := rand.New(rand.NewSource(99))
load := r.Int63n(5000000)
loads <- load
}
close(jobs)
close(loads)
// Finally we collect all the results of the work.
for a := 1; a <= 24; a++ {
<-results
}
}
我一直收到这个错误消息......
prog.go:18:33：无法将load（type <-chan int）转换为time.Duration
prog.go:36:18：调用worker的参数不足有（int，chan int，chan int）想要（int，<-chan int，<-chan int，chan < - int）
prog.go:45:15：不能在send中使用load（类型int64）作为int类型
我究竟做错了什么？
即使你修复了编译错误，你仍然会遇到问题。
//worker_pool improved example
package main
import "fmt"
import "time"
import "math/rand"
// 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 random number of seconds between
// 1 and 5 to simulate an expensive task.
func worker(id int, jobs <-chan int, loads <-chan time.Duration, results chan<- int) {
for j := range jobs {
fmt.Println("worker", id, "started job", j, time.Now())
time.Sleep(<-loads * time.Second)
fmt.Println("worker", id, "finished job", j, time.Now())
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)
loads := make(chan time.Duration)
results := make(chan int)
// This starts up 3 workers, initially blocked
// because there are no jobs yet.
for w := 1; w <= 3; w++ {
go worker(w, jobs, loads, results)
}
// Here we send 24 `jobs` and then `close` that
// channel to indicate that's all the work we have.
for j := 1; j <= 24; j++ {
jobs <- j
r := rand.New(rand.NewSource(99))
load := time.Duration(r.Int63n(5000000))
loads <- load
}
close(jobs)
close(loads)
// Finally we collect all the results of the work.
for a := 1; a <= 24; a++ {
<-results
}
}
游乐场：https://play.golang.org/p/tVdlKFHunKN
输出：
worker 3 started job 1 2009-11-10 23:00:00 +0000 UTC m=+0.000000001
worker 1 started job 2 2009-11-10 23:00:00 +0000 UTC m=+0.000000001
worker 2 started job 3 2009-11-10 23:00:00 +0000 UTC m=+0.000000001
worker 1 finished job 2 2009-12-27 17:05:41 +0000 UTC m=+4039541.000000001
worker 3 finished job 1 2009-12-27 17:05:41 +0000 UTC m=+4039541.000000001
worker 2 finished job 3 2009-12-27 17:05:41 +0000 UTC m=+4039541.000000001
fatal error: all goroutines are asleep - deadlock!
确实代码存在问题。
我创建的频道没有缓冲。我为作业和结果通道添加了100个缓冲区（每个原始示例），程序运行正常。
//worker_pool improved example
package main
import "fmt"
import "time"
import "math/rand"
func worker(id int, jobs <-chan int, loads <-chan time.Duration, results chan<- int) {
for j := range jobs {
before := time.Now()
fmt.Println("worker", id, "started job", j)
time.Sleep(<-loads)
after := time.Now()
fmt.Println("worker", id, "finished job", j, "in", after.Sub(before))
results <- j
}
}
func main() {
jobs := make(chan int, 100) // Buffered channel
loads := make(chan time.Duration)
results := make(chan int, 100) // Buffered channel
for w := 1; w <= 3; w++ {
go worker(w, jobs, loads, results)
}
for j := 1; j <= 24; j++ {
jobs <- j
r := rand.New(rand.NewSource(int64(j*10)))
loads <- time.Duration(r.Int63n(500000000)) // In nano seconds
}
close(jobs)
close(loads)
for a := 1; a <= 24; a++ {
<-results
}
}
游乐场：https://play.golang.org/p/bz-JIkD1OoG
我仍然习惯于随机生成器逻辑。在给定某种种子的情况下，它每次返回完全相同的数字，这在我的脑海中打败了随机性的概念。
部分结果......
worker 3 started job 1
worker 1 started job 2
worker 2 started job 3
worker 1 finished job 2 in 168.00641ms
worker 1 started job 4
worker 3 finished job 1 in 205.826435ms
worker 3 started job 5
worker 3 finished job 5 in 160.909863ms
worker 3 started job 6
worker 2 finished job 3 in 381.707665ms