GO by example, part 4

5-go-by-example/35-worker-pools.go

@@ -0,0 +1,41 @@
+package main
+
+import (
+	"fmt"
+	"time"
+)
+
+// worker, of which will run several concurrent instances
+// those workers will receive work on the jobs channel and send the corresponding results on results
+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() {
+
+	// send workers work and collect their results
+	const numJobs = 5
+	jobs := make(chan int, numJobs)
+	results := make(chan int, numJobs)
+
+	// starts up 3 workers, initially blocked because there are no jobs
+	for w := 1; w <= 3; w++ {
+		go worker(w, jobs, results)
+	}
+
+	// send 5 jobs and then close that channel
+	for j := 1; j <= numJobs; j++ {
+		jobs <- j
+	}
+	close(jobs)
+
+	// collect all the results of the work
+	for a := 1; a <= numJobs; a++ {
+		<-results
+	}
+}