Go concurrency examples

sleepsort1.go

package main

import (
	"fmt"
	"time"
)

func sleepSort(array []int) []int {
	rc := make(chan int)

	postpone := func(v int) {
		time.Sleep(time.Duration(v) * time.Millisecond)
		rc <- v
	}
	max := 0
	for _, v := range array {
		go postpone(v)
		if v > max {
			max = v
		}
	}
	res := make([]int, 0)
	for {
		v := <-rc
		res = append(res, v)
		if v == max {
			return res
		}
	}
}

func main() {
	fmt.Println(sleepSort([]int{43, 2, 3, 10, 22, -10, 7, 2, 3, 100, -1, -2}))
}

sleepsort_waitgroup.go

package main

import (
	"fmt"
	"sync"
	"time"
)

func sleepSort(array []int) []int {
	rc := make(chan int)
	postpone := func(v int, wg *sync.WaitGroup) {
		time.Sleep(time.Duration(v) * time.Millisecond)
		rc <- v
		wg.Done()
	}

	var wg sync.WaitGroup
	max := 0
	for _, v := range array {
		wg.Add(1)
		go postpone(v, &wg)
		if v > max {
			max = v
		}
	}
	res := make([]int, 0)
	go func() {
		for {
			v := <-rc
			res = append(res, v)
		}
	}()
	wg.Wait()
	return res
}

func main() {
	fmt.Println(sleepSort([]int{43, 2, 3, 10, 22, -10, 7, 2, 3, 100, -1, -2}))
}

worker_pool.go

package main

import (
	"fmt"
	//"math/rand"
	"time"
)

func generator(c chan<- int) {
	v := 0
	for {
		v++
		time.Sleep(200 * time.Millisecond)
		// v := rand.Intn(100)
		fmt.Println("Generated", v)
		c <- v
	}
}

func worker(n int, in <-chan int, out chan<- int) {
	for {
		v := <-in
		fmt.Println("worker", n, "got", v)
		time.Sleep(5000 * time.Millisecond)
		fmt.Println("worker", n, "processed", v)
		out <- v
	}
}

func reader(c <-chan int) {
	for {
		v := <-c
		fmt.Println("Pull outputs", v)
	}
}

func main() {
	data := make(chan int, 10)
	results := make(chan int, 10)
	go generator(data)
	for i := 0; i < 10; i++ {
		go worker(i, data, results)
	}
	reader(results)
}