Spring boot @Async 注解抛出 LazyInitializationException

Question

我有一个 emailsenderservice 来异步管理电子邮件通知。 有 2 种异步方法，一种方法有效，另一种方法抛出 LazyInitializationException：

@Service
public class EmailSenderService {
    // working
    @Async
    public void sendNewBidRequestEmail(BidRequest bidRequest) {
        this.sendNewBidRequestEmailToSupplier(bidRequest);
    }
    @Transactional
    public void sendNewBidRequestEmailToSupplier(BidRequest bidRequest) {
        sendNewBidRequestEmailToSupplier(bidRequest, bidRequest.getHotels());
    }

    @Transactional
    public void sendNewBidRequestEmailToSupplier(BidRequest bidRequest, List<Hotel> hotelList) {
        for (Hotel hotel : hotelList) {
           ...
           this.sender.send()
        }
    }


    // not working, throw exception
    @Async
    public void sendCancelledBidRequestEmail(BidRequest bidRequest, String reason) {
        this.sendCancelledBidRequestEmailToSupplier(bidRequest, bidRequest.getHotels(), reason);
    }

    @Transactional
    public void sendCancelledBidRequestEmailToSupplier(BidRequest bidRequest, List<Hotel> hotelList, String reason) {
        for (Hotel hotel : hotelList) {   // throw exception here
           ...
           this.sender.send();
        }
}

我完全关注this thread。 您可以看到两个异步方法具有几乎相同的结构。异步方法调用事务方法。但是第二个抛出org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.corpobids.server.entity.BidRequest.hotels, could not initialize proxy - no Session。

我什至模仿第一个异步方法结构将第二个修改为：

@Async
    public void sendCancelledBidRequestEmail(BidRequest bidRequest, String reason) {
        this.sendCancelledBidRequestEmailToSupplier(bidRequest, reason);
    }

    @Transactional
    public void sendCancelledBidRequestEmailToSupplier(BidRequest bidRequest, String reason) {
        this.sendCancelledBidRequestEmailToSupplier(bidRequest, bidRequest.getHotels(), reason);
    }

    @Transactional
    public void sendCancelledBidRequestEmailToSupplier(BidRequest bidRequest, List<Hotel> hotelList, String reason) {
        for (Hotel hotel : hotelList) {   // exception in this line
               ...
               this.sender.send();
            }
    }
}

这一次，它给了我java.lang.IllegalStateException: org.hibernate.resource.jdbc.internal.LogicalConnectionManagedImpl@fce9b7b is closed。

我想知道我的代码中的缺失点，任何帮助将不胜感激。

Answer 1

您对 JPA 有疑问。

在 JPA 中，OneToMany 关系有两种行为 LAZY 和 EAGER。

你可以查看一个很好的解释：Difference between FetchType LAZY and EAGER in Java Persistence API?

我假设当您在异步模式下调用代码时，JPA 的上下文是松散的。因此，由于上下文不同，Hibernate 无法填充执行新查询的关系。为了解决您的问题，您有两种选择：

1. 配置与 EAGER 的关系
2. 在调用异步方法之前预加载关系

使用延迟加载更好的潜在客户技术：

https://www.thoughts-on-java.org/5-ways-to-initialize-lazy-relations-and-when-to-use-them/