import org.springframework.stereotype.Service;

@Service
public class SynchronizedLockService {
    private int counter = 0;

    public synchronized void increment() {
        counter++;
        System.out.println(Thread.currentThread().getName() + " - 현재 카운트: " + counter);
    }
}

CREATE TABLE lock_table (
    id INT PRIMARY KEY,
    locked BOOLEAN NOT NULL DEFAULT FALSE
);

    @Transactional
    public void doSomethingWithLock() {
        // 행 잠금 (SELECT FOR UPDATE)
        jdbcTemplate.queryForObject("SELECT * FROM lock_table WHERE id = 1 FOR UPDATE", (rs, rowNum) -> rs.getInt("id"));

        System.out.println(Thread.currentThread().getName() + " - 데이터베이스 Lock 획득!");
        try {
            Thread.sleep(5000); // 작업 수행
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println(Thread.currentThread().getName() + " - 작업 완료!");
    }