Concurrency bugs like overselling happen when multiple transactions read and modify the same data simultaneously. @Transactional alone doesn't prevent this. Two strategies address it: Optimistic Locking uses a version column to detect conflicts at update time (throwing OptimisticLockException on collision), while Pessimistic Locking uses SELECT FOR UPDATE to block concurrent access entirely. Spring Boot implementations are shown for both using @Version and @Lock(LockModeType.PESSIMISTIC_WRITE). Optimistic locking suits read-heavy, low-conflict scenarios; pessimistic locking suits high-stakes operations like payments and inventory where consistency is critical. Real systems typically use both depending on the use case.
Table of contents
IntroductionThe ProblemWhy Does This Happen?Is @Transactional Enough?What is Database Locking?Optimistic LockingConceptFlowSpring Boot ImplementationAdvantagesDisadvantagesBest Use CasesPessimistic LockingConceptGet Nakul Mitra’s stories in your inboxFlowSpring Boot ImplementationAdvantagesDisadvantagesBest Use CasesOptimistic vs Pessimistic LockingWhich One Should You Choose?Choose Optimistic Locking when:Choose Pessimistic Locking when:How Real Companies Use ThemE-commerceBanking ApplicationsSocial Media PlatformsRelationship with Previous TutorialsKey Takeaways37.5K Impressions