How does sync.RWMutex work and when should it be used?

sync.RWMutex in Go is a type of mutex that allows multiple goroutines to read data simultaneously (RLock), but blocks writing (Lock) until all readers have released the lock.

When to use:

• If you have data that is read frequently and rarely modified.
• To improve performance by allowing parallel reads but excluding concurrent writes.

Example:

var mu sync.RWMutex
var data int

func readData() int {
    mu.RLock()
    defer mu.RUnlock()
    return data
}

func writeData(val int) {
    mu.Lock()
    defer mu.Unlock()
    data = val
}

Thus, multiple calls to readData can execute simultaneously, but writeData will wait until all reads are finished and will block new reads until the write is complete.