Read-Write Lock in Go

main.go

package main

// Just a sample code for learning mutex. Don't use this code for prodution.

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

type Account struct {
	sync.RWMutex
	balance int
}

func (acc *Account) Update(amount int) int {
	acc.Lock()
	defer acc.Unlock()

	acc.balance += amount
	// if write operation is pretty fast (fast like there's no write operation at all), the performace of using read-write lock is approximate to simple lock
	time.Sleep(200 * time.Millisecond)
	return acc.balance
}

func (acc *Account) Get() int {
	acc.RLock()
	defer acc.RUnlock()

	time.Sleep(800 * time.Millisecond)

	return acc.balance
}

func main() {

	account := Account{
		balance: 100,
	}

	var wg sync.WaitGroup
	start := time.Now()

	// try to modify k to 2 to see what will happen
	// k:=2
	k := 10

	for i := 0; i < 100; i++ {

		if i%k == 0 {
			wg.Add(1)
			go func(n int) {
				defer wg.Done()
				fmt.Println("Writing", account.Update(n/10))
			}(i)
		} else {
			wg.Add(1)
			// rw lock is good for reading
			go func() {
				defer wg.Done()
				fmt.Println("Reading", account.Get())
			}()
		}
	}

	wg.Wait()
	end := time.Now()

	fmt.Println("Duration", end.Sub(start))
}