[root@wangjq queue]# cat work.go
package mainimport "time"type WorkRequest struct {Name  stringDelay time.Duration
}

[root@wangjq queue]# cat collector.go
package mainimport ("fmt""net/http""time"
)// A buffered channel that we can send work requests on.
var WorkQueue = make(chan WorkRequest, 100)func Collector(w http.ResponseWriter, r *http.Request) {// Make sure we can only be called with an HTTP POST request.if r.Method != "POST" {w.Header().Set("Allow", "POST")w.WriteHeader(http.StatusMethodNotAllowed)return}// Parse the delay.delay, err := time.ParseDuration(r.FormValue("delay"))if err != nil {http.Error(w, "Bad delay value: "+err.Error(), http.StatusBadRequest)return}// Check to make sure the delay is anywhere from 1 to 10 seconds.if delay.Seconds() < 1 || delay.Seconds() > 10 {http.Error(w, "The delay must be between 1 and 10 seconds, inclusively.", http.StatusBadRequest)return}// Now, we retrieve the person's name from the request.name := r.FormValue("name")// Just do a quick bit of sanity checking to make sure the client actually provided us with a name.if name == "" {http.Error(w, "You must specify a name.", http.StatusBadRequest)return}// Now, we take the delay, and the person's name, and make a WorkRequest out of them.work := WorkRequest{Name: name, Delay: delay}// Push the work onto the queue.WorkQueue <- workfmt.Println("Work request queued")// And let the user know their work request was created.
        w.WriteHeader(http.StatusCreated)return
}

[root@wangjq queue]# cat worker.go
package mainimport ("fmt""time"
)// NewWorker creates, and returns a new Worker object. Its only argument
// is a channel that the worker can add itself to whenever it is done its
// work.
func NewWorker(id int, workerQueue chan chan WorkRequest) Worker {// Create, and return the worker.worker := Worker{ID:          id,Work:        make(chan WorkRequest),WorkerQueue: workerQueue,QuitChan:    make(chan bool)}return worker
}type Worker struct {ID          intWork        chan WorkRequestWorkerQueue chan chan WorkRequestQuitChan    chan bool
}// This function "starts" the worker by starting a goroutine, that is
// an infinite "for-select" loop.
func (w *Worker) Start() {go func() {for {// Add ourselves into the worker queue.w.WorkerQueue <- w.Workselect {case work := <-w.Work:// Receive a work request.fmt.Printf("worker%d: Received work request, delaying for %f seconds\n", w.ID, work.Delay.Seconds())time.Sleep(work.Delay)fmt.Printf("worker%d: Hello, %s!\n", w.ID, work.Name)case <-w.QuitChan:// We have been asked to stop.fmt.Printf("worker%d stopping\n", w.ID)return}}}()
}// Stop tells the worker to stop listening for work requests.
//
// Note that the worker will only stop *after* it has finished its work.
func (w *Worker) Stop() {go func() {w.QuitChan <- true}()
}

[root@wangjq queue]# cat dispatcher.go
package mainimport "fmt"var WorkerQueue chan chan WorkRequestfunc StartDispatcher(nworkers int) {// First, initialize the channel we are going to but the workers' work channels into.WorkerQueue = make(chan chan WorkRequest, nworkers)// Now, create all of our workers.for i := 0; i < nworkers; i++ {fmt.Println("Starting worker", i+1)worker := NewWorker(i+1, WorkerQueue)worker.Start()}go func() {for {select {case work := <-WorkQueue:fmt.Println("Received work requeust")go func() {worker := <-WorkerQueuefmt.Println("Dispatching work request")worker <- work}()}}}()
}

[root@wangjq queue]# cat main.go
package mainimport ("flag""fmt""net/http"
)var (NWorkers = flag.Int("n", 4, "The number of workers to start")HTTPAddr = flag.String("http", "127.0.0.1:8000", "Address to listen for HTTP requests on")
)func main() {// Parse the command-line flags.
        flag.Parse()// Start the dispatcher.fmt.Println("Starting the dispatcher")StartDispatcher(*NWorkers)// Register our collector as an HTTP handler function.fmt.Println("Registering the collector")http.HandleFunc("/work", Collector)// Start the HTTP server!fmt.Println("HTTP server listening on", *HTTPAddr)if err := http.ListenAndServe(*HTTPAddr, nil); err != nil {fmt.Println(err.Error())}
}

[root@wangjq queue]# go build -o queued *.go

[root@wangjq queue]# ./queued -n 5
Starting the dispatcher
Starting worker 1
Starting worker 2
Starting worker 3
Starting worker 4
Starting worker 5
Registering the collector
HTTP server listening on 127.0.0.1:8000

[root@wangjq ~]# for i in {1..3}; do curl localhost:8000/work -d name=$USER -d delay=$(expr $i % 11)s; done

[root@wangjq queue]# ./queued -n 5
Starting the dispatcher
Starting worker 1
Starting worker 2
Starting worker 3
Starting worker 4
Starting worker 5
Registering the collector
HTTP server listening on 127.0.0.1:8000
Work request queued
Received work requeust
Dispatching work request
worker1: Received work request, delaying for 1.000000 seconds
Work request queued
Received work requeust
Dispatching work request
worker2: Received work request, delaying for 2.000000 seconds
Work request queued
Received work requeust
Dispatching work request
worker4: Received work request, delaying for 3.000000 seconds
worker1: Hello, root!
worker2: Hello, root!
worker4: Hello, root!