What can you tell about the Reader-Writer problem?

The problem of Reader-Writer lock occurs when multiple threads access shared data, where some only read and others write.

The main goal is to:

• Allow multiple readers to read simultaneously without blocking.
• Ensure that writers have exclusive access, blocking other readers and writers.

To solve this, special synchronization mechanisms called Reader-Writer locks are used. They allow:

• Multiple threads to read concurrently.
• Write access to be exclusive, blocking others.

This improves performance compared to simple mutexes, which block all access.

In iOS/Swift, similar tasks can be implemented using DispatchQueue with barriers (barrier), or NSLock/pthread_rwlock_t for Reader-Writer locks.