Goroutines example. Use the time command to verify the elapsed time to finish the execution.

basic_goroutines.go

// goroutines errors example

package main

import (
	"errors"
	"fmt"
	"time"
)

func returnError(text string) error {
	if text == "error" {
		return errors.New("err")
	}

	return nil
}

func main() {
	err1 := make(chan error)
	err2 := make(chan error)

	// all "go func" run asynchronously
	go func() {
		// this function needs 10 seconds
		time.Sleep(time.Second * 10)
		err1 <- returnError("error")
	}()

	go func() {
		// this function needs 5 second
		time.Sleep(time.Second * 5)
		err2 <- returnError("error")
	}()

	// synchronous code from here
	err := <-err1
	if err != nil {
		fmt.Println("g1", err)
	}

	err = <-err2
	if err != nil {
		fmt.Println("g2", err)
	}

	close(err1)
	close(err2)
}