Golang Coroutines Quickstart (https://www.youtube.com/watch?v=anACPPJCNVA)

squencial cooking.go

package main

import (
	"fmt"
	"time"
)

func main() {
	since := time.Now()
	// cooking
	foodList := []string{"mushroom pizza", "pasta", "kebab", "cake"}
	for _, food := range foodList {
		cook(food)
	}
	// time
	fmt.Printf("took %.0f sec to cook\n", time.Since(since).Seconds())
}

// cook cook the food
func cook(food string) {
	fmt.Printf("cooking %s\n", food)
	time.Sleep(2 * time.Second)
}

/*
output:
took 8 second to cook
*/

sync coroutine cook wait.go

package main

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

func main() {
	since := time.Now()
	// cooking
	foodList := []string{"mushroom pizza", "pasta", "kebab", "cake"}

	// create a WaitGroup for waiting for coroutines
	var wg sync.WaitGroup
	// add the number of tasks to wait for
	wg.Add(len(foodList))

	for _, food := range foodList {
		// use a simple coroutine (this will fail as we do not wait for cooking to complete
		go func(f string) {
			cook(f)
			// call done when cooking completes
			wg.Done()
		}(food)
	}
	// wait
	wg.Wait()

	// time
	fmt.Printf("took %.0f sec to cook\n", time.Since(since).Seconds())
}

// cook cook the food
func cook(food string) {
	fmt.Printf("cooking %s\n", food)
	time.Sleep(2 * time.Second)
}

/*
output:
took 2 second to cook
*/

sync coroutine cook.go

package main

import (
	"fmt"
	"time"
)

func main() {
	since := time.Now()
	// cooking
	foodList := []string{"mushroom pizza", "pasta", "kebab", "cake"}
	for _, food := range foodList {
		// use a simple coroutine (this will fail as we do not wait for cooking to complete
    // we call the cook function wrapped in a function that we call using a coroutine
		go func(f string) {
			cook(f)
		}(food)
    // or just
    // go cook(food)
    // works as we call cook in a coroutine
	}
	// time
	fmt.Printf("took %.0f sec to cook\n", time.Since(since).Seconds())
}

// cook cook the food
func cook(food string) {
	fmt.Printf("cooking %s\n", food)
	time.Sleep(2 * time.Second)
}

/*
output:
took 0 second to cook
*/