What Is the Difference Between Mutex and RwLock in Rust?

A Mutex allows only one thread to access data at a time, while an RwLock allows multiple readers or one writer simultaneously. Use Mutex when writes are frequent, and RwLock when reads dominate to improve concurrency.

use std::sync::{Mutex, RwLock};

// Mutex: Exclusive access for reading or writing
let m = Mutex::new(5);
let mut num = m.lock().unwrap();
*num = 6;

// RwLock: Multiple readers or one writer
let rw = RwLock::new(5);
let read_guard = rw.read().unwrap(); // Multiple threads can hold this
let mut write_guard = rw.write().unwrap(); // Only one thread can hold this
*write_guard = 10;

Think of a Mutex like a single-key bathroom: only one person can enter at a time, whether they are just looking or using it. An RwLock is like a library reading room: many people can read books at once, but if someone needs to write in a book, everyone else must leave. You choose based on whether your data is mostly read or mostly changed.