Optimistic/Pessimistic Locking with JPA

Optimistic Locking

• with JPA (Java Persistence API)
• Instead of locking resources, it allows multiple threads to update the same resource and check for conflicts at the commit stage
• Use a version number

    @Entity
    public class BankAccount {
        @Id
        private Long id;
        private double balance;
        @Version
        private int version; // Tracks changes for optimistic locking
    }

Pessimistic Locking

• Lock resources upfront to prevent other threads from accessing them
• Other threads/transactions are blocked until the lock is released
• Use Case: High-write, high-conflict scenario, critical system(e.g. bank transfer)
• Use ReentrantLock