How Laravel Handles Concurrency with Transactions, Atomicity, and Locking

Concurrent database requests in Laravel applications can cause race conditions, where two users simultaneously read the same data and both proceed with an action like a purchase. Atomicity, one of the four ACID properties, ensures that a group of database operations either all succeed or all roll back, which Laravel implements via DB::transaction(). To prevent race conditions, Laravel offers pessimistic locking through lockForUpdate(), which locks a row before it is read and modified, forcing other requests to wait until the lock is released. A sharedLock() alternative is available for protected reads where no modification is intended. Optimistic locking offers yet another strategy by skipping row locks and instead detecting conflicts after the fact, suited for scenarios where simultaneous edits are infrequent.