What Is the Difference Between Mutex and RWMutex in Go

A sync.Mutex allows only one goroutine to hold the lock at a time, blocking all others, while a sync.RWMutex allows multiple readers or a single writer. Use RWMutex when your data is read frequently but written rarely to improve concurrency.

import "sync"

// Mutex: Exclusive access (Read or Write)
var mu sync.Mutex
mu.Lock()
// Critical section
mu.Unlock()

// RWMutex: Multiple readers OR one writer
var rwmu sync.RWMutex

// Reading (multiple allowed)
rwmu.RLock()
// Read data
rwmu.RUnlock()

// Writing (exclusive)
rwmu.Lock()
// Write data
rwmu.Unlock()

Think of a Mutex as a single-person bathroom: only one person can enter at a time, regardless of what they are doing. An RWMutex is like a library: many people can read books at the same time, but if someone needs to write a book, everyone else must wait until they are finished. Use RWMutex when you have mostly read operations to let more people work simultaneously.