- Java 17
- Docker, Docker-Compose
- Gradle
- SpringBoot 3.2.0
cd docker;
docker-compose -f docker-compose-mysql.yaml up -d;
docker exec -it $(docker ps | grep mysql | awk -F" " '{ print $1}') bash;
mysql -u root
create database test;public interface StockRepository extends JpaRepository<Stock, Long> {
@Lock(LockModeType.PESSIMISTIC_WRITE)
@Query("select s from Stock s where s.id = :id")
Optional<Stock> findByIdWithPessimisticLock(@Param("id") Long id);
}재고 관리시스템 구현 코드 예시
@Service
public class StockPessimisticLockService implements StockCommand {
private final StockRepository stockRepository;
public StockPessimisticLockService(StockRepository stockRepository) {
this.stockRepository = stockRepository;
}
/**
* Decrease stock quantity.
* @param id Product ID
* @param quantity Quantity to decrease
* @throws IllegalStateException If the stock quantity is less than the quantity to decrease
*/
@Transactional
@Override
public void decreaseStockQuantity(Long id, Long quantity) {
Stock stock = stockRepository.findByIdWithPessimisticLock(id)
.orElseThrow(IllegalStateException::new);
stock.decrease(quantity);
}
}public interface StockRepository extends JpaRepository<Stock, Long> {
@Lock(LockModeType.OPTIMISTIC)
@Query("select s from Stock s where s.id = :id")
Optional<Stock> findByIdWithOptimisticLock(@Param("id") Long id);
}재고 관리시스템 구현 코드 예시
@Component
public class StockOptimisticLockFacade implements StockCommand {
private final StockOptimisticLockService stockOptimisticLockService;
public StockOptimisticLockFacade(StockOptimisticLockService stockOptimisticLockService) {
this.stockOptimisticLockService = stockOptimisticLockService;
}
@Override
public void decreaseStockQuantity(Long id, Long quantity) {
try {
// Retry until success
retryUntilSuccess(() ->
stockOptimisticLockService.decreaseStockQuantity(id, quantity)
);
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
}
}
private void retryUntilSuccess(Runnable runnable) throws InterruptedException {
while (true) {
try {
runnable.run();
break;
} catch (RuntimeException e) {
// retry
Thread.sleep(500);
}
}
}
}SELECT GET_LOCK('lock_name', 1000);
SELECT RELEASE_LOCK('lock_name');@Query(value = "SELECT GET_LOCK(:key, 3000)", nativeQuery = true)
void getLock(@Param("key") String key);
@Query(value = "SELECT RELEASE_LOCK(:key)", nativeQuery = true)
void releaseLock(@Param("key") String key);재고 관리시스템 구현 코드 예시
@Component
public class StockNamedLockFacade implements StockCommand {
private final NamedLockRepository namedLockRepository;
private final StockService stockService;
public StockNamedLockFacade(NamedLockRepository namedLockRepository, StockService stockService) {
this.namedLockRepository = namedLockRepository;
this.stockService = stockService;
}
@Override
public void decreaseStockQuantity(Long id, Long quantity) {
try {
namedLockRepository.lock(id.toString());
stockService.decreaseStockQuantity(id, quantity);
} finally {
namedLockRepository.unlock(id.toString());
}
}
}setnx명령어를 사용하여 락을 획득한다.- spin lock 방식으로 락을 획득한다.
- 동시에 많은 쓰레드가 Lock 획득 대기 상태일 경우, Redis에 부하가 걸릴 수 있다.
@Component
public class RedisLockRepository {
private final RedisTemplate<String, String> redisTemplate;
public RedisLockRepository(RedisTemplate<String, String> redisTemplate) {
this.redisTemplate = redisTemplate;
}
/**
* Lock product by ID with Redis Lock (Lettuce)
* @param id Product ID
* @return true if lock is acquired, false otherwise
*/
public Boolean lock(Long id) {
return redisTemplate
.opsForValue()
.setIfAbsent(id.toString(), "lock", Duration.ofSeconds(3));
}
/**
* Unlock product by ID with Redis Lock (Lettuce)
* @param id Product ID
* @return true if lock is released, false otherwise
*/
public Boolean unlock(Long id) {
return redisTemplate.delete(id.toString());
}
}재고 관리시스템 구현 코드 예시
@Component
public class StockLettuceLockFacade implements StockCommand {
private final RedisLockRepository redisLockRepository;
private final StockService stockService;
public StockLettuceLockFacade(
RedisLockRepository redisLockRepository,
StockService stockService) {
this.redisLockRepository = redisLockRepository;
this.stockService = stockService;
}
/**
* Decrease stock quantity with Redis Lock (Lettuce)
* @param id Product ID
* @param quantity Quantity to decrease
*/
@Override
public void decreaseStockQuantity(Long id, Long quantity) {
try {
while (Boolean.FALSE.equals(redisLockRepository.lock(id))) {
sleep(100); // Spin Lock
}
stockService.decreaseStockQuantity(id, quantity);
} finally {
redisLockRepository.unlock(id);
}
}
private void sleep(long millis) {
try {
Thread.sleep(millis);
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
}
}
}pub/sub방식으로 락을 획득한다.- Lettuce에 비해 Redis에 대한 부하가 적다.
- 별도의 라이브러리를 사용해야한다.
implementation 'org.redisson:redisson-spring-boot-starter:3.24.3'
재고 관리시스템 구현 코드 예시
@Component
public class StockRedissonLockFacade implements StockCommand {
private final RedissonClient redissonClient;
private final StockService stockService;
public StockRedissonLockFacade(RedissonClient redissonClient, StockService stockService) {
this.redissonClient = redissonClient;
this.stockService = stockService;
}
/**
* Decrease stock quantity with Redisson Lock
* @param id Product ID
* @param quantity Quantity to decrease
*/
@Override
public void decreaseStockQuantity(Long id, Long quantity) {
RLock lock = redissonClient.getLock(id.toString());
try {
// pub-sub Lock
boolean isLocked = lock.tryLock(10, 1, TimeUnit.SECONDS);
if (!isLocked) {
throw new IllegalStateException("Failed to acquire lock");
}
stockService.decreaseStockQuantity(id, quantity);
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
} finally {
lock.unlock();
}
}
}