go-routines.go

package main

import (
	"fmt"
	"time"
)

func f(from string) {
	for i := 0; i < 3; i++ {
		fmt.Println(from, ":", i)
	}
}

// GoRoutines illustrate go routines
func GoRoutines() {
	// A goroutine is a lightweight thread of execution.

	// Suppose we have a function call f(s). Here’s how we’d call that in the usual way, running it synchronously.
	f("direct")

	// To invoke this function in a goroutine, use go f(s). This new goroutine will execute concurrently with the calling one.
	go f("goroutine")

	// You can also start a goroutine for an anonymous function call.
	go func(msg string) {
		fmt.Println(msg)
	}("going")

	// Our two function calls are running asynchronously in separate goroutines now,
	// so execution falls through to here. This Scanln requires we press a key before the program exits.
	time.Sleep(2 * time.Second)
	fmt.Println("Done")

	// When we run this program, we see the output of the blocking call first,
	// then the interleaved output of the two goroutines.
	// This interleaving reflects the goroutines being run concurrently by the Go runtime.

}