Could you explain the principle of mutual exclusion (Mutex) and its use in multithreaded programs?

Mutual exclusion (Mutex) is a synchronization mechanism used to prevent multiple threads from simultaneously accessing a shared resource (such as a variable or file). A mutex guarantees that only one thread can own the lock and execute the critical section at any given time.

Working principle:

• A thread attempts to acquire the mutex before entering the critical section.
• If the mutex is free, the thread gains access and continues.
• If the mutex is occupied by another thread, the current thread is blocked and waits for it to be released.
• After finishing with the resource, the thread releases the mutex, allowing other threads to proceed.

In Go, this is implemented using the sync.Mutex type:

var mu sync.Mutex
var counter int

func increment() {
    mu.Lock()         // acquire mutex
    counter++         // critical section
    mu.Unlock()       // release mutex
}

Using a mutex prevents race conditions and ensures data correctness during parallel execution.