인프런 커뮤니티 질문&답변

분명 현재 없는 상태이고

결과가 자꾸 이상하게 나와서 sout 처리를 잠시 해보았습니다

package com.example.api.service;

import com.example.api.domain.Coupon;
import com.example.api.repository.CouponCountRepository;
import com.example.api.repository.CouponRepository;
import org.springframework.stereotype.Service;

@Service
public class ApplyService {

    private final CouponRepository couponRepository;
    private final CouponCountRepository couponCountRepository;

    public ApplyService(CouponRepository couponRepository, CouponCountRepository couponCountRepository) {
        this.couponRepository = couponRepository;
        this.couponCountRepository = couponCountRepository;
    }

    public void applyV1(Long userId) {
        Long count = couponRepository.count();

        if(count > 100) {
            return;
        }

        couponRepository.save(new Coupon(userId));
    }

    public void applyV2(Long userId) {
        Long count = couponCountRepository.increment();
        System.out.println(count);

        if(count > 100) {
            return;
        }

        couponRepository.save(new Coupon(userId));
    }

}

@SpringBootTest
class ApplyServiceTest {

    @Autowired
    private ApplyService applyService;

    @Autowired
    private CouponRepository couponRepository;

    @Test
    public void applyOnce() {
        applyService.applyV1(1L);

        long count = couponRepository.count();
        Assertions.assertEquals(1L, count);
    }

    @Test
    public void 여러명응모V1() throws InterruptedException {
        int threadCount = 1000;
        ExecutorService executorService = Executors.newFixedThreadPool(32);
        CountDownLatch latch = new CountDownLatch(threadCount);

        for(int i=0; i<threadCount; i++){
            long userId = i;
            executorService.submit(() -> {
                try {
                    applyService.applyV1(userId);
                } catch(Exception e) {
                    System.out.println(e);
                }finally {
                    latch.countDown();
                }
            });
        }
        latch.await();

        long count = couponRepository.count();

        assertThat(count).isEqualTo(100);
    }

    @Test
    public void 여러명응모V2() throws InterruptedException {
        int threadCount = 1000;
        ExecutorService executorService = Executors.newFixedThreadPool(32);
        CountDownLatch latch = new CountDownLatch(threadCount);

        for(int i=0; i<threadCount; i++){
            long userId = i;
            executorService.submit(() -> {
                try {
                    applyService.applyV2(userId);
                } catch(Exception e) {
                    System.out.println(e);
                }finally {
                    latch.countDown();
                }
            });
        }
        latch.await();

        long count = couponRepository.count();

        org.assertj.core.api.Assertions.assertThat(count).isEqualTo(100);
    }

}

그런데 여러명응모V2 test를 실행시에 count를 출력시

다음과 같은 수가 나옵니다.

20003

20011

20012

20013

20015

20016

20017

20018

20020

20022

???

한번 할때마다 1000씩 쿠폰의 수가 증가중인데요;;;

조회했을때는 empty라 나오는데 이렇게 되는 연유를 잘 모르갰습니다.

테스트 코드라서 rollback이 되야할거 같은데 그렇지 않는것도 잘 모르겟네요;; ㅠㅠ