Just a simple example of a mutex during race condition.

mutexEx.go

package main

import (
	"fmt"
	"runtime"
	"sync"
)

func main() {

	var wg sync.WaitGroup
	c := 0
	wg.Add(100)

	var mux sync.Mutex

	for i := 0; i < 100; i++ {
		go func() {
			mux.Lock()
			count := c
			runtime.Gosched()
			count++
			c = count
			fmt.Println(c)
			wg.Done()
			mux.Unlock()
		}()
	}
	wg.Wait()

	fmt.Println("End value: ", c)

}