How does Rails handle high-scale distributed locking and concurrency control?

Rails uses database locks, Redis-based locks, and optimistic concurrency control to manage distributed consistency.

Concurrency control ensures that multiple processes do not modify the same resource simultaneously. Rails supports optimistic locking using version columns and pessimistic locking using SELECT FOR UPDATE. For distributed systems, Redis-based locking mechanisms (like Redlock) are commonly used. These systems must handle race conditions, lock expiration, and network partitions carefully.