What is the difference between Mutex and RWMutex?

Mutex (mutual exclusion) is a simple locking mechanism that allows only one goroutine to access the critical section of code at a time.

RWMutex (Read-Write Mutex) extends this idea by allowing multiple goroutines to read data simultaneously (permitting parallel read operations), but blocking access during writing. That is:

• Multiple readers can hold the lock simultaneously.
• Writing is only possible when there are no readers or other writers.

Example of using RWMutex:

var mu sync.RWMutex
var data int

func readData() int {
    mu.RLock()           // lock for reading
    defer mu.RUnlock()
    return data
}

func writeData(val int) {
    mu.Lock()            // lock for writing
    defer mu.Unlock()
    data = val
}

Thus, RWMutex improves performance in scenarios with frequent read operations and infrequent writes.