[REFACTOR] 메일 비동기 전송 구현

src/main/java/synk/meeteam/domain/recruitment/recruitment_applicant/facade/RecruitmentApplicantFacade.java

@@ -39,7 +39,10 @@ public void approveApplicant(Long postId, Long userId, List<Long> applicantIds)
 
         RecruitmentPost recruitmentPost = recruitmentPostService.getRecruitmentPost(postId);
         User user = userService.findById(recruitmentPost.getCreatedBy());
-        mailService.sendApproveMails(postId, applicants, user.getName());
+
+        applicants.stream().forEach(
+                applicant -> mailService.sendApproveMail(postId, applicant, user.getName())
+        );
     }
 
     @Transactional

src/main/java/synk/meeteam/domain/recruitment/recruitment_applicant/repository/RecruitmentApplicantRepository.java

@@ -16,7 +16,7 @@
 public interface RecruitmentApplicantRepository extends JpaRepository<RecruitmentApplicant, Long>,
         RecruitmentApplicantCustomRepository {
 
-    @Query("SELECT a FROM RecruitmentApplicant a JOIN FETCH a.recruitmentPost WHERE a.id IN :ids AND a.deleteStatus = synk.meeteam.global.entity.DeleteStatus.ALIVE")
+    @Query("SELECT a FROM RecruitmentApplicant a JOIN FETCH a.recruitmentPost JOIN FETCH a.applicant WHERE a.id IN :ids AND a.deleteStatus = synk.meeteam.global.entity.DeleteStatus.ALIVE")
     List<RecruitmentApplicant> findAllInApplicantId(@Param("ids") List<Long> applicantIds);
 
     Optional<RecruitmentApplicant> findByRecruitmentPostAndApplicantAndDeleteStatus(RecruitmentPost recruitmentPost,

src/main/java/synk/meeteam/global/config/AsyncConfig.java

@@ -0,0 +1,23 @@
+package synk.meeteam.global.config;
+
+import java.util.concurrent.Executor;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.scheduling.annotation.AsyncConfigurerSupport;
+import org.springframework.scheduling.annotation.EnableAsync;
+import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;
+
+@Configuration
+@EnableAsync
+public class AsyncConfig extends AsyncConfigurerSupport {
+
+    public Executor getAsyncExecutor() {
+        ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
+        executor.setCorePoolSize(2); // 기본적으로 실행 대기 중인 Thread 개수
+        executor.setMaxPoolSize(10); // 동시에 동작하는 최대 Thread 개수
+        executor.setQueueCapacity(500); // CorePool이 초과될때 Queue에 저장했다가 꺼내서 실행된다. (500개까지 저장함)
+
+        executor.setThreadNamePrefix("async-"); // Spring에서 생성하는 Thread 이름의 접두사
+        executor.initialize();
+        return executor;
+    }
+}

src/main/java/synk/meeteam/infra/mail/MailService.java

@@ -15,11 +15,11 @@
 import jakarta.mail.internet.InternetAddress;
 import jakarta.mail.internet.MimeMessage;
 import jakarta.mail.internet.MimeMessage.RecipientType;
-import java.util.List;
 import java.util.UUID;
 import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
 import org.springframework.mail.javamail.JavaMailSender;
+import org.springframework.scheduling.annotation.Async;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
 import org.thymeleaf.TemplateEngine;
@@ -74,6 +74,7 @@ public String generateEmailVerifyMailForm(String userName, String emailCode) {
         return templateEngine.process(MAIL_VERIFY_TEMPLATE, context);
     }
 
+    @Async
     @Transactional
     public void sendVerifyMail(String platformId, String receiverMail) {
         String newEmailCode = UUID.randomUUID().toString();
@@ -100,35 +101,34 @@ public void sendVerifyMail(String platformId, String receiverMail) {
         }
     }
 
+
+    @Async
     @Transactional
-    public void sendApproveMails(Long postId, List<RecruitmentApplicant> applicants, String writerName) {
-        if (applicants == null) {
-            return;
-        }
+    public void sendApproveMail(Long postId, RecruitmentApplicant recruitmentApplicant, String writerName) {
+
         MimeMessage message = mailSender.createMimeMessage();
 
-        for (RecruitmentApplicant recruitmentApplicant : applicants) {
-            User applicant = recruitmentApplicant.getApplicant();
-            String receiverMail =
-                    applicant.isUniversityMainEmail() ? applicant.getUniversityEmail() : applicant.getSubEmail();
-
-            try {
-                message.addRecipients(RecipientType.TO, receiverMail);// 받는 대상
-                message.setSubject(MAIL_TITLE_APPROVE);// 제목
-
-                String body = generateApproveMailForm(applicant.getName(), postId.toString(),
-                        recruitmentApplicant.getRecruitmentPost().getTitle(),
-                        recruitmentApplicant.getRole().getName(), writerName,
-                        recruitmentApplicant.getRecruitmentPost().getKakaoLink());
-
-                message.setText(body, CHAR_SET, SUB_TYPE);// 내용, charset 타입, subtype
-                // 보내는 사람의 이메일 주소, 보내는 사람 이름
-                message.setFrom(new InternetAddress(SENDER_ADDRESS, SENDER));// 보내는 대상
-                mailSender.send(message); // 메일 전송
-            } catch (Exception e) {
-                log.info("{}", e);
-                throw new AuthException(INVALID_MAIL_SERVICE);
-            }
+        User applicant = recruitmentApplicant.getApplicant();
+
+        String receiverMail =
+                applicant.isUniversityMainEmail() ? applicant.getUniversityEmail() : applicant.getSubEmail();
+
+        try {
+            message.addRecipients(RecipientType.TO, receiverMail);// 받는 대상
+            message.setSubject(MAIL_TITLE_APPROVE);// 제목
+
+            String body = generateApproveMailForm(applicant.getName(), postId.toString(),
+                    recruitmentApplicant.getRecruitmentPost().getTitle(),
+                    recruitmentApplicant.getRole().getName(), writerName,
+                    recruitmentApplicant.getRecruitmentPost().getKakaoLink());
+
+            message.setText(body, CHAR_SET, SUB_TYPE);// 내용, charset 타입, subtype
+            // 보내는 사람의 이메일 주소, 보내는 사람 이름
+            message.setFrom(new InternetAddress(SENDER_ADDRESS, SENDER));// 보내는 대상
+            mailSender.send(message); // 메일 전송
+        } catch (Exception e) {
+            log.info("{}", e);
+            throw new AuthException(INVALID_MAIL_SERVICE);
         }
 
     }