Apache Isis 列出实体的操作太慢，发现 2 个问题/疑问

Question

使用演示应用程序 PetClinic 作为示例。仅关注 PetOwner，不关注其他实体。一些宠物主人已预先插入到数据库中。 演示中的操作“listAll”：

    @Action(semantics = SemanticsOf.SAFE)
    @ActionLayout(bookmarking = BookmarkPolicy.AS_ROOT)
    public List<PetOwner> listAll() {
        return petOwnerRepository.findAll();
    }

当调用操作“listAll”时，我们发现两个与延迟相关的问题。

1. 发出大量查询，每个实体一个 这是对 jpa 的查询，这是有意义的

[EL Fine]: sql: 2022-03-10 14:50:50.303--ClientSession(1477740542)--Connection(716488272)--SELECT id, NAME, NOTES, version FROM pets.PETOWNER

，并且还会有更多查询出现：

[EL Fine]: sql: 2022-03-10 14:50:50.436--ClientSession(840311416)--Connection(1724151743)--SELECT id, NAME, NOTES, version FROM pets.PETOWNER WHERE (id = ?)
    bind => [1]
[EL Fine]: sql: 2022-03-10 14:50:50.437--ClientSession(840311416)--Connection(1724151743)--SELECT id, NAME, NOTES, version FROM pets.PETOWNER WHERE (id = ?)
    bind => [2]
[EL Fine]: sql: 2022-03-10 14:50:50.437--ClientSession(840311416)--Connection(1724151743)--SELECT id, NAME, NOTES, version FROM pets.PETOWNER WHERE (id = ?)
    bind => [3]
[EL Fine]: sql: 2022-03-10 14:50:50.437--ClientSession(840311416)--Connection(1724151743)--SELECT id, NAME, NOTES, version FROM pets.PETOWNER WHERE (id = ?)
    bind => [4]
[EL Fine]: sql: 2022-03-10 14:50:50.438--ClientSession(840311416)--Connection(1724151743)--SELECT id, NAME, NOTES, version FROM pets.PETOWNER WHERE (id = ?)
    bind => [5]
[EL Fine]: sql: 2022-03-10 14:50:50.438--ClientSession(840311416)--Connection(1724151743)--SELECT id, NAME, NOTES, version FROM pets.PETOWNER WHERE (id = ?)
    bind => [6]
[EL Fine]: sql: 2022-03-10 14:50:50.438--ClientSession(840311416)--Connection(1724151743)--SELECT id, NAME, NOTES, version FROM pets.PETOWNER WHERE (id = ?)
    bind => [7]
[EL Fine]: sql: 2022-03-10 14:50:50.438--ClientSession(840311416)--Connection(1724151743)--SELECT id, NAME, NOTES, version FROM pets.PETOWNER WHERE (id = ?)
    bind => [8]
[EL Fine]: sql: 2022-03-10 14:50:50.439--ClientSession(840311416)--Connection(1724151743)--SELECT id, NAME, NOTES, version FROM pets.PETOWNER WHERE (id = ?)
    bind => [9]
[EL Fine]: sql: 2022-03-10 14:50:50.439--ClientSession(840311416)--Connection(1724151743)--SELECT id, NAME, NOTES, version FROM pets.PETOWNER WHERE (id = ?)
    bind => [10]
[EL Fine]: sql: 2022-03-10 14:50:50.439--ClientSession(840311416)--Connection(1724151743)--SELECT id, NAME, NOTES, version FROM pets.PETOWNER WHERE (id = ?)
    bind => [11]
[EL Fine]: sql: 2022-03-10 14:50:50.44--ClientSession(840311416)--Connection(1724151743)--SELECT id, NAME, NOTES, version FROM pets.PETOWNER WHERE (id = ?)
    bind => [12]
[EL Fine]: sql: 2022-03-10 14:50:50.44--ClientSession(840311416)--Connection(1724151743)--SELECT id, NAME, NOTES, version FROM pets.PETOWNER WHERE (id = ?)
    bind => [13]

Apache Isis 内部是否有任何配置/设置来不进行这些查询？因为从第一个查询开始我就认为我们已经把一切都做好了？

2. 即使没有这些查询，我们仍然会看到延迟。 因此，为了解决这个问题，我们引入了一个 DTO 类作为视图模型，以将域实体与列表结果

DTO 类解耦：

@DomainObject(nature = Nature.VIEW_MODEL,logicalTypeName = "cps.PetOwnerDtoViewModel")
@XmlRootElement(name = "PetOwnerDtoViewModel")
@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(
        propOrder = {
                "name",
                "notes"
        }
)
public class PetOwnerDto {
        private String name;
        private String notes;

...(constructor and getter setter)
}

并将 DTO 列表包装到另一个视图模型中，因为我们需要稍后添加针对集合的操作。 （如此处建议的 ISIS：从已弃用的 @Action(invokeOn=...) @Action(associateWith=...))

@DomainObject(nature = Nature.VIEW_MODEL,logicalTypeName = "cps.PetOwnersViewModel")
@XmlRootElement(name = "PetOwnersViewModel")
@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(
        propOrder = {
                "petOwnerList"
        }
)
@NoArgsConstructor(access = AccessLevel.PUBLIC)
public class PetOwnersViewModel {
    public String title() {
        return "Owners";
    }

    @XmlElementWrapper
    @XmlElement(name = "petOwnerList")
    @Getter
    @Setter
    @CollectionLayout(paged = 5)
    protected List<PetOwnerDto> petOwnerList = new LinkedList<>();

    public PetOwnersViewModel(List<PetOwnerDto> results) {
        this.petOwnerList = results;
    }

}

我们创建了一个新操作来返回 PetOwnerViewModel：

    @Action(semantics = SemanticsOf.SAFE)
    @ActionLayout(bookmarking = BookmarkPolicy.AS_ROOT)
    public PetOwnersViewModel listAllDto() {
        List<PetOwner> petOwnerList = petOwnerRepository.findAll();
        LinkedList<PetOwnerDto> petOwnerDtos = new LinkedList<>();
        for (PetOwner p : petOwnerList) {
            petOwnerDtos.add(new PetOwnerDto(p));
        }
        return new PetOwnersViewModel(petOwnerDtos);
    }

这样只有一个查询会发送到db，没有发现额外的查询。 然后我们向数据库加载了 1000 个宠物主人。使用 @CollectionLayout(paged = 5) 时，延迟仍然存在但可以接受，但如果我们单击“显示全部”，则需要 20 秒才能显示所有 1000 行数据。这个操作需要这么长时间有什么原因吗？既然所有需要的数据都已经从数据库中提取了，对吧？

谢谢，希望有人能帮忙！

Answer 1

正式来说，这不是一个答案（只是一条评论）：

感谢您在这里报告您的观察结果！我确实打开了 Jira 票证以进行进一步调查：

https://issues.apache.org/ jira/浏览/ISIS-2973