56_Spring 플러스 주차 개인 과제 트러블슈팅_25.3.20(목)

2025.03.20(목)

Spring 플러스 주차 개인 과제 트러블슈팅

도전

Lv 3-12. AWS 활용

aws pc에서 java -jar expert-0.0.1-SNAPSHOT.jar 실행 시 문제 발생

2025-03-20T00:53:21.644Z ERROR 4655 --- [expert] [           main] o.s.b.web.embedded.tomcat.TomcatStarter  : Error starting Tomcat context. Exception: org.springframework.beans.factory.UnsatisfiedDependencyException. Message: Error creating bean with name 'jwtAuthenticationFilter' defined in URL [jar:nested:/home/ubuntu/expert-0.0.1-SNAPSHOT.jar/!BOOT-INF/classes/!/org/example/expert/config/JwtAuthenticationFilter.class]: Unsatisfied dependency expressed through constructor parameter 0: Error creating bean with name 'jwtUtil': Injection of autowired dependencies failed
2025-03-20T00:53:21.713Z  INFO 4655 --- [expert] [           main] o.apache.catalina.core.StandardService   : Stopping service [Tomcat]
2025-03-20T00:53:21.756Z  WARN 4655 --- [expert] [           main] ConfigServletWebServerApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.context.ApplicationContextException: Unable to start web server
2025-03-20T00:53:21.789Z  INFO 4655 --- [expert] [           main] .s.b.a.l.ConditionEvaluationReportLogger : 

Error starting ApplicationContext. To display the condition evaluation report re-run your application with 'debug' enabled.
2025-03-20T00:53:21.827Z ERROR 4655 --- [expert] [           main] o.s.boot.SpringApplication               : Application run failed

org.springframework.context.ApplicationContextException: Unable to start web server
        at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.onRefresh(ServletWebServerApplicationContext.java:165) ~[spring-boot-3.3.3.jar!/:3.3.3]
        at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:619) ~[spring-context-6.1.12.jar!/:6.1.12]
        at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:146) ~[spring-boot-3.3.3.jar!/:3.3.3]
        at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:754) ~[spring-boot-3.3.3.jar!/:3.3.3]
        at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:456) ~[spring-boot-3.3.3.jar!/:3.3.3]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:335) ~[spring-boot-3.3.3.jar!/:3.3.3]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1363) ~[spring-boot-3.3.3.jar!/:3.3.3]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1352) ~[spring-boot-3.3.3.jar!/:3.3.3]
        at org.example.expert.ExpertApplication.main(ExpertApplication.java:14) ~[!/:0.0.1-SNAPSHOT]
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77) ~[na:na]
        at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
        at java.base/java.lang.reflect.Method.invoke(Method.java:569) ~[na:na]
        at org.springframework.boot.loader.launch.Launcher.launch(Launcher.java:102) ~[expert-0.0.1-SNAPSHOT.jar:0.0.1-SNAPSHOT]
        at org.springframework.boot.loader.launch.Launcher.launch(Launcher.java:64) ~[expert-0.0.1-SNAPSHOT.jar:0.0.1-SNAPSHOT]
        at org.springframework.boot.loader.launch.JarLauncher.main(JarLauncher.java:40) ~[expert-0.0.1-SNAPSHOT.jar:0.0.1-SNAPSHOT]
Caused by: org.springframework.boot.web.server.WebServerException: Unable to start embedded Tomcat
        at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.initialize(TomcatWebServer.java:147) ~[spring-boot-3.3.3.jar!/:3.3.3]
        at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.<init>(TomcatWebServer.java:107) ~[spring-boot-3.3.3.jar!/:3.3.3]
        at org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory.getTomcatWebServer(TomcatServletWebServerFactory.java:516) ~[spring-boot-3.3.3.jar!/:3.3.3]
        at org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory.getWebServer(TomcatServletWebServerFactory.java:222) ~[spring-boot-3.3.3.jar!/:3.3.3]
        at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.createWebServer(ServletWebServerApplicationContext.java:188) ~[spring-boot-3.3.3.jar!/:3.3.3]
        at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.onRefresh(ServletWebServerApplicationContext.java:162) ~[spring-boot-3.3.3.jar!/:3.3.3]
        ... 15 common frames omitted
Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'jwtAuthenticationFilter' defined in URL [jar:nested:/home/ubuntu/expert-0.0.1-SNAPSHOT.jar/!BOOT-INF/classes/!/org/example/expert/config/JwtAuthenticationFilter.class]: Unsatisfied dependency expressed through constructor parameter 0: Error creating bean with name 'jwtUtil': Injection of autowired dependencies failed
        at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:795) ~[spring-beans-6.1.12.jar!/:6.1.12]
        at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:237) ~[spring-beans-6.1.12.jar!/:6.1.12]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireConstructor(AbstractAutowireCapableBeanFactory.java:1375) ~[spring-beans-6.1.12.jar!/:6.1.12]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1212) ~[spring-beans-6.1.12.jar!/:6.1.12]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:562) ~[spring-beans-6.1.12.jar!/:6.1.12]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:522) ~[spring-beans-6.1.12.jar!/:6.1.12]
        at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:337) ~[spring-beans-6.1.12.jar!/:6.1.12]
        at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[spring-beans-6.1.12.jar!/:6.1.12]
        at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:335) ~[spring-beans-6.1.12.jar!/:6.1.12]
        at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:205) ~[spring-beans-6.1.12.jar!/:6.1.12]
        at org.springframework.boot.web.servlet.ServletContextInitializerBeans.getOrderedBeansOfType(ServletContextInitializerBeans.java:211) ~[spring-boot-3.3.3.jar!/:3.3.3]
        at org.springframework.boot.web.servlet.ServletContextInitializerBeans.addAsRegistrationBean(ServletContextInitializerBeans.java:174) ~[spring-boot-3.3.3.jar!/:3.3.3]
        at org.springframework.boot.web.servlet.ServletContextInitializerBeans.addAsRegistrationBean(ServletContextInitializerBeans.java:169) ~[spring-boot-3.3.3.jar!/:3.3.3]
        at org.springframework.boot.web.servlet.ServletContextInitializerBeans.addAdaptableBeans(ServletContextInitializerBeans.java:154) ~[spring-boot-3.3.3.jar!/:3.3.3]
        at org.springframework.boot.web.servlet.ServletContextInitializerBeans.<init>(ServletContextInitializerBeans.java:87) ~[spring-boot-3.3.3.jar!/:3.3.3]
        at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.getServletContextInitializerBeans(ServletWebServerApplicationContext.java:266) ~[spring-boot-3.3.3.jar!/:3.3.3]
        at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.selfInitialize(ServletWebServerApplicationContext.java:240) ~[spring-boot-3.3.3.jar!/:3.3.3]
        at org.springframework.boot.web.embedded.tomcat.TomcatStarter.onStartup(TomcatStarter.java:52) ~[spring-boot-3.3.3.jar!/:3.3.3]
        at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:4414) ~[tomcat-embed-core-10.1.28.jar!/:na]
        at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:164) ~[tomcat-embed-core-10.1.28.jar!/:na]
        at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1203) ~[tomcat-embed-core-10.1.28.jar!/:na]
        at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1193) ~[tomcat-embed-core-10.1.28.jar!/:na]
        at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264) ~[na:na]
        at org.apache.tomcat.util.threads.InlineExecutorService.execute(InlineExecutorService.java:75) ~[tomcat-embed-core-10.1.28.jar!/:na]
        at java.base/java.util.concurrent.AbstractExecutorService.submit(AbstractExecutorService.java:145) ~[na:na]
        at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:749) ~[tomcat-embed-core-10.1.28.jar!/:na]
        at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:772) ~[tomcat-embed-core-10.1.28.jar!/:na]
        at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:164) ~[tomcat-embed-core-10.1.28.jar!/:na]
        at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1203) ~[tomcat-embed-core-10.1.28.jar!/:na]
        at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1193) ~[tomcat-embed-core-10.1.28.jar!/:na]
        at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264) ~[na:na]
        at org.apache.tomcat.util.threads.InlineExecutorService.execute(InlineExecutorService.java:75) ~[tomcat-embed-core-10.1.28.jar!/:na]
        at java.base/java.util.concurrent.AbstractExecutorService.submit(AbstractExecutorService.java:145) ~[na:na]
        at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:749) ~[tomcat-embed-core-10.1.28.jar!/:na]
        at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:203) ~[tomcat-embed-core-10.1.28.jar!/:na]
        at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:164) ~[tomcat-embed-core-10.1.28.jar!/:na]
        at org.apache.catalina.core.StandardService.startInternal(StandardService.java:415) ~[tomcat-embed-core-10.1.28.jar!/:na]
        at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:164) ~[tomcat-embed-core-10.1.28.jar!/:na]
        at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:874) ~[tomcat-embed-core-10.1.28.jar!/:na]
        at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:164) ~[tomcat-embed-core-10.1.28.jar!/:na]
        at org.apache.catalina.startup.Tomcat.start(Tomcat.java:437) ~[tomcat-embed-core-10.1.28.jar!/:na]
        at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.initialize(TomcatWebServer.java:128) ~[spring-boot-3.3.3.jar!/:3.3.3]
        ... 20 common frames omitted
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'jwtUtil': Injection of autowired dependencies failed
        at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessProperties(AutowiredAnnotationBeanPostProcessor.java:515) ~[spring-beans-6.1.12.jar!/:6.1.12]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1439) ~[spring-beans-6.1.12.jar!/:6.1.12]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:599) ~[spring-beans-6.1.12.jar!/:6.1.12]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:522) ~[spring-beans-6.1.12.jar!/:6.1.12]
        at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:337) ~[spring-beans-6.1.12.jar!/:6.1.12]
        at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[spring-beans-6.1.12.jar!/:6.1.12]
        at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:335) ~[spring-beans-6.1.12.jar!/:6.1.12]
        at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:200) ~[spring-beans-6.1.12.jar!/:6.1.12]
        at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:254) ~[spring-beans-6.1.12.jar!/:6.1.12]
        at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1443) ~[spring-beans-6.1.12.jar!/:6.1.12]
        at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1353) ~[spring-beans-6.1.12.jar!/:6.1.12]
        at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:904) ~[spring-beans-6.1.12.jar!/:6.1.12]
        at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:782) ~[spring-beans-6.1.12.jar!/:6.1.12]
        ... 61 common frames omitted
Caused by: java.lang.IllegalArgumentException: Could not resolve placeholder 'JWT_SECRET_KEY' in value "${JWT_SECRET_KEY}"
        at org.springframework.util.PropertyPlaceholderHelper.parseStringValue(PropertyPlaceholderHelper.java:180) ~[spring-core-6.1.12.jar!/:6.1.12]
        at org.springframework.util.PropertyPlaceholderHelper.replacePlaceholders(PropertyPlaceholderHelper.java:126) ~[spring-core-6.1.12.jar!/:6.1.12]
        at org.springframework.core.env.AbstractPropertyResolver.doResolvePlaceholders(AbstractPropertyResolver.java:239) ~[spring-core-6.1.12.jar!/:6.1.12]
        at org.springframework.core.env.AbstractPropertyResolver.resolveRequiredPlaceholders(AbstractPropertyResolver.java:210) ~[spring-core-6.1.12.jar!/:6.1.12]
        at org.springframework.core.env.AbstractPropertyResolver.resolveNestedPlaceholders(AbstractPropertyResolver.java:230) ~[spring-core-6.1.12.jar!/:6.1.12]
        at org.springframework.boot.context.properties.source.ConfigurationPropertySourcesPropertyResolver.getProperty(ConfigurationPropertySourcesPropertyResolver.java:80) ~[spring-boot-3.3.3.jar!/:3.3.3]
        at org.springframework.boot.context.properties.source.ConfigurationPropertySourcesPropertyResolver.getProperty(ConfigurationPropertySourcesPropertyResolver.java:61) ~[spring-boot-3.3.3.jar!/:3.3.3]
        at org.springframework.core.env.AbstractEnvironment.getProperty(AbstractEnvironment.java:552) ~[spring-core-6.1.12.jar!/:6.1.12]
        at org.springframework.context.support.PropertySourcesPlaceholderConfigurer$1.getProperty(PropertySourcesPlaceholderConfigurer.java:153) ~[spring-context-6.1.12.jar!/:6.1.12]
        at org.springframework.context.support.PropertySourcesPlaceholderConfigurer$1.getProperty(PropertySourcesPlaceholderConfigurer.java:149) ~[spring-context-6.1.12.jar!/:6.1.12]
        at org.springframework.core.env.PropertySourcesPropertyResolver.getProperty(PropertySourcesPropertyResolver.java:85) ~[spring-core-6.1.12.jar!/:6.1.12]
        at org.springframework.core.env.PropertySourcesPropertyResolver.getPropertyAsRawString(PropertySourcesPropertyResolver.java:74) ~[spring-core-6.1.12.jar!/:6.1.12]
        at org.springframework.util.PropertyPlaceholderHelper.parseStringValue(PropertyPlaceholderHelper.java:153) ~[spring-core-6.1.12.jar!/:6.1.12]
        at org.springframework.util.PropertyPlaceholderHelper.replacePlaceholders(PropertyPlaceholderHelper.java:126) ~[spring-core-6.1.12.jar!/:6.1.12]
        at org.springframework.core.env.AbstractPropertyResolver.doResolvePlaceholders(AbstractPropertyResolver.java:239) ~[spring-core-6.1.12.jar!/:6.1.12]
        at org.springframework.core.env.AbstractPropertyResolver.resolveRequiredPlaceholders(AbstractPropertyResolver.java:210) ~[spring-core-6.1.12.jar!/:6.1.12]
        at org.springframework.context.support.PropertySourcesPlaceholderConfigurer.lambda$processProperties$0(PropertySourcesPlaceholderConfigurer.java:200) ~[spring-context-6.1.12.jar!/:6.1.12]
        at org.springframework.beans.factory.support.AbstractBeanFactory.resolveEmbeddedValue(AbstractBeanFactory.java:964) ~[spring-beans-6.1.12.jar!/:6.1.12]
        at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1374) ~[spring-beans-6.1.12.jar!/:6.1.12]
        at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1353) ~[spring-beans-6.1.12.jar!/:6.1.12]
        at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.resolveFieldValue(AutowiredAnnotationBeanPostProcessor.java:785) ~[spring-beans-6.1.12.jar!/:6.1.12]
        at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:768) ~[spring-beans-6.1.12.jar!/:6.1.12]
        at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:145) ~[spring-beans-6.1.12.jar!/:6.1.12]
        at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessProperties(AutowiredAnnotationBeanPostProcessor.java:509) ~[spring-beans-6.1.12.jar!/:6.1.12]
        ... 73 common frames omitted

 

jwt.secret.key를 application.properties에서 환경변수로 설정했었는데

이 정보가 jar 파일에는 설정되지 않아서 발생한 문제로 보인다.

다시 이 부분을 수정하고 build하니 잘 되었다.

 

rds 생성해서 연결해주니

아래와 같이 잘 연결된 것을 확인할 수 있다.

 

---

Lv 3-13. 대용량 데이터 처리

JPA Repository saveAll()이 아닌 JdbcTemplate를 사용해야 하는 이유

 

수정 전

100만건 데이터 입력에 JPA Repository saveAll()을 사용했었다.

@SpringBootTest
@Commit
@Transactional
class GenerateUsersTest {

    @Autowired
    private UserRepository userRepository;

    @Autowired
    private EntityManager entityManager;

    @Test
    void 유저_100만건_생성() {
        List<User> users = new ArrayList<>();
        for (int i = 0; i < 1_000_000; i++) {
            UserRole userRole = i % 2 == 0 ? UserRole.ROLE_USER : UserRole.ROLE_ADMIN;
            users.add(new User("email" + i, "password" + i, userRole, "nickname" + i));

            if (i % 10_000 == 0 && i > 0) {
                userRepository.saveAll(users);
                entityManager.flush(); // 즉시 DB 반영
                users.clear();
            }
        }

        // 마지막 남은 데이터 저장
        if (!users.isEmpty()) {
            userRepository.saveAll(users);
            entityManager.flush();
        }
    }
}

 

그러나 튜터님께서 saveAll() 메서드를 잘 살펴보라고 하셔서 들어가서 보았다.

for문을 통해서 일일이 리스트에 저장하고 있는 것을 확인할 수 있었다.

이런 상태에서는 100만 건의 데이터를 넣을 수 없다는 것을 알 수 있었다.

@Transactional
public <S extends T> List<S> saveAll(Iterable<S> entities) {
    Assert.notNull(entities, "Entities must not be null");
    List<S> result = new ArrayList();

    for(S entity : entities) {
        result.add(this.save(entity));
    }

    return result;
}

 

추가로 공식문서를 보면 아래와 같이JPA saveAll()은 Batch Insert 방식으로 작동하지 않는 이유에 대해서도 알 수 있었다.

"@GeneratedValue(strategy = GenerationType.IDENTITY)의 경우 Hibernate는 JDBC 수준에서 batch insert를 비활성화한다"

출처: https://twosky.tistory.com/62

 

수정 후

따라서 JPA Repository가 아닌 JdbcTemplate Repository를 가지고 100만 건을 생성했다.

@Repository
@RequiredArgsConstructor
public class UserJdbcRepository {

    private final JdbcTemplate jdbcTemplate;

    public void saveAllUsers(List<User> users) {
        String sql = "INSERT INTO users (email, password, user_role, nickname) VALUES (?, ?, ?, ?)";
        jdbcTemplate.batchUpdate(sql, new BatchPreparedStatementSetter() {
            @Override
            public void setValues(PreparedStatement ps, int i) throws SQLException {
                User user = users.get(i);
                ps.setString(1, user.getEmail());
                ps.setString(2, user.getPassword());
                ps.setString(3, user.getUserRole().name());
                ps.setString(4, user.getNickname());
            }

            @Override
            public int getBatchSize() {
                return users.size();
            }
        });
    }
}

 

@SpringBootTest
@TestInstance(TestInstance.Lifecycle.PER_CLASS)
class GenerateUsers {

    @Autowired
    private UserJdbcRepository userJdbcRepository;

    private static final int USER_INSERT_COUNT = 1_000_000;
    private static final int BATCH_SIZE = 1_000;

    @Test
    @Transactional
    @Rollback(value = false)
    void 유저_100만건_생성() {
        List<User> users = new ArrayList<>();
        for (int i = 0; i < USER_INSERT_COUNT; i++) {
            UserRole userRole = i % 2 == 0 ? UserRole.ROLE_USER : UserRole.ROLE_ADMIN;
            users.add(new User("email" + i + "@naver.com", "Password" + i, userRole, "nickname" + i));

            if (i % BATCH_SIZE == 0 && i > 0) {
                userJdbcRepository.saveAllUsers(users);
                users.clear();
                /* 배치 사이즈마다 0.5초씩 sleep 처리 */
                try {
                    Thread.sleep(500);
                } catch (InterruptedException e) {
                    throw new RuntimeException(e);
                }
            }
        }

        if (!users.isEmpty()) {
            userJdbcRepository.saveAllUsers(users);
        }
    }
}