golang mutex

main.go

// refer to http://stackoverflow.com/questions/8286806/go-programming-language-mutual-concurrent-execution
// https://gobyexample.com/mutexes
package main

import "sync"

var m sync.Mutex
var wg sync.WaitGroup

func routine1() {
    ... do something ...

    m.Lock()
    ... critical section (access the shared resource here) ...
    m.Unlock()

    ... do something ...
    wg.Done()
}

func routine2() {
    ... do something ...

    m.Lock()
    ... critical section (access the shared resource here) ...
    m.Unlock()

    ... do something ...
    wg.Done()
}

func main() {
    wg.Add(1); go routine1()
    wg.Add(1); go routine2()
    wg.Wait()
}