What is in the sync package?

The sync package in Go provides synchronization primitives for managing concurrent access to resources.

Main components of the package:

• Mutex — a mutex for mutual exclusion, blocks access to a resource.
• RWMutex — a read-write mutex, allows multiple readers or one writer at a time.
• WaitGroup — allows waiting for a group of goroutines to finish.
• Once — ensures a function is only executed once.
• Cond — a condition variable for signaling and waiting for events.

Example of using Mutex:

var mu sync.Mutex
var counter int

func increment() {
    mu.Lock()
    defer mu.Unlock()
    counter++
}

This package is essential for safe handling of shared data in concurrent programs.