What is the difference between mutex and RWMutex in Go?

Question

Accepted Answer

**Mutex** — exclusive lock. **RWMutex** — allows multiple readers.

**sync.Mutex:**
- Exclusive lock.
- Only one goroutine at a time.
- Both read and write.

```go
var mu sync.Mutex

func Read() {
    mu.Lock()
    // Read data
    mu.Unlock()
}

func Write() {
    mu.Lock()
    // Write data
    mu.Unlock()
}
```

**sync.RWMutex:**
- Multiple readers OR single writer.
- RLock/RUnlock for readers.
- Lock/Unlock for writers.

```go
var rwmu sync.RWMutex

func Read() {
    rwmu.RLock()
    // Read data — multiple can read
    rwmu.RUnlock()
}

func Write() {
    rwmu.Lock()
    // Write data — exclusive
    rwmu.Unlock()
}
```

**When to use RWMutex:**
- Read-heavy workloads.
- Many readers, few writers.
- Better performance than Mutex.

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