Is it possible to write to the same map from different goroutines simultaneously? What will happen?

In Go, it is not safe to write to a single map from multiple goroutines simultaneously without additional synchronization. The standard map is not thread-safe, and concurrent write operations can lead to a panic (runtime panic) or data corruption.

To safely use a map in a concurrent environment, you can:

• Use sync.Mutex or sync.RWMutex to protect access to the map.
• Use sync.Map — a specialized thread-safe data structure for maps.

Example with mutex:

var (
    m = make(map[string]int)
    mu sync.Mutex
)

func write(key string, value int) {
    mu.Lock()
    m[key] = value
    mu.Unlock()
}

Without such protection, the program may crash.