How to Implement the Reader-Writer Lock Pattern in Go

Use sync.RWMutex to allow multiple concurrent readers or a single exclusive writer. Create a struct embedding sync.RWMutex, then call RLock()/RUnlock() for reads and Lock()/Unlock() for writes.

package main

import (
	"sync"
)

type DataStore struct {
	mu   sync.RWMutex
	data map[string]int
}

func (s *DataStore) Read(key string) int {
	s.mu.RLock()
	defer s.mu.RUnlock()
	return s.data[key]
}

func (s *DataStore) Write(key string, val int) {
	s.mu.Lock()
	defer s.mu.Unlock()
	s.data[key] = val
}

The Reader-Writer Lock pattern in Go lets many goroutines read shared data simultaneously, but only one can write at a time. It prevents crashes when multiple parts of your program try to change data simultaneously. Think of it like a library where many people can read books, but only one person can check a book out to write in it.