CompositeAttributeFlusher throws NPE on some operations

[EugenMayer]

In some cases (i cannot simply reproduce it), we get this error in our production logs

2023/07/10 13:02:50 [e2e-firefox] ERROR [http-nio-8080-exec-10] o.a.c.c.C.[.[.[.[dispatcherServlet] ⬩ Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed: java.lang.NullPointerException: Cannot invoke "com.blazebit.persistence.view.impl.update.flush.CompositeAttributeFlusher.flushEntity(com.blazebit.persistence.view.impl.update.UpdateContext, Object, Object, Object, Object, java.lang.Runnable)" because "this.fullFlusher" is null] with root cause
java.lang.NullPointerException: Cannot invoke "com.blazebit.persistence.view.impl.update.flush.CompositeAttributeFlusher.flushEntity(com.blazebit.persistence.view.impl.update.UpdateContext, Object, Object, Object, Object, java.lang.Runnable)" because "this.fullFlusher" is null
	at com.blazebit.persistence.view.impl.update.EntityViewUpdaterImpl.executePersist(EntityViewUpdaterImpl.java:732) ~[blaze-persistence-entity-view-impl-jakarta-1.6.9.jar!/:1.6.9]
	at com.blazebit.persistence.view.impl.update.EntityViewUpdaterImpl.executePersist(EntityViewUpdaterImpl.java:727) ~[blaze-persistence-entity-view-impl-jakarta-1.6.9.jar!/:1.6.9]
	at com.blazebit.persistence.view.impl.EntityViewManagerImpl.update(EntityViewManagerImpl.java:1191) ~[blaze-persistence-entity-view-impl-jakarta-1.6.9.jar!/:1.6.9]
	at com.blazebit.persistence.view.impl.EntityViewManagerImpl.update(EntityViewManagerImpl.java:1153) ~[blaze-persistence-entity-view-impl-jakarta-1.6.9.jar!/:1.6.9]
	at com.blazebit.persistence.view.impl.EntityViewManagerImpl.save(EntityViewManagerImpl.java:1070) ~[blaze-persistence-entity-view-impl-jakarta-1.6.9.jar!/:1.6.9]
	at de.kontextwork.dw.platform.commons.jpa.sql.blazepersistence.RegularEntityViewRepository.create(RegularEntityViewRepository.java:227) ~[platform-commons-20230710.7.jar!/:?]
	at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:?]
	at jdk.internal.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[?:?]

This is the create view that is used in this case

@EntityView(SpaceContentStructureNode.class)
@CreatableEntityView
public interface SpaceContentStructureNodeCreateView extends SpaceContentStructureNodeIdView
{
  Integer getPosition();

  void setPosition(Integer position);

  SpaceContentStructureNodeIdView getParent();

  void setParent(SpaceContentStructureNodeIdView parent);

  SpaceIdView getSpace();

  void setSpace(SpaceIdView spaceIdView);

  PageIdView getPage();

  void setPage(PageIdView pageIdView);
}

and this is the entity

@Entity
@Data
@Table(name = "dw_space_content_structure")
@EqualsAndHashCode(onlyExplicitlyIncluded = true)
public class SpaceContentStructureNode implements Serializable
{
  @Id
  @Include
  @Column(name = "id", columnDefinition = "INT(10)")
  @GeneratedValue(strategy = GenerationType.IDENTITY)
  private Long id;

  @ManyToOne
  private SpaceContentStructureNode parent;

  @OrderColumn(name = "position")
  @OneToMany(mappedBy = "parent", fetch = FetchType.LAZY, cascade = CascadeType.REMOVE)
  private Set<SpaceContentStructureNode> children;

  @ManyToOne(fetch = FetchType.LAZY)
  @JoinColumn(name = "node_id", referencedColumnName = "nid", columnDefinition = "INT(10) UNSIGNED")
  private Page page;

  @ManyToOne(fetch = FetchType.LAZY)
  @JoinColumn(name = "space_id", referencedColumnName = "id", columnDefinition = "INT(10) UNSIGNED")
  private Space space;

  /**
   * Custom sort field normalized between 1 (first) and unlimited (last).
   * Normalized means, we are ensuring, that if we insert a TreeNode as a child,
   * all the position values of the children are a unique sequence starting from 1
   *
   * see SpaceContentStructureRepository#insertRelativeToNeighbor
   */
  @Column(columnDefinition = "INT(10)")
  private Integer position;
}

Yet not sure what to provide and how to further narrow it down, maybe this needs a discussion.

i## Env

• BP 1.6.9
• HIbernate 6.2.6
• Java 17
• Spring boot 3.1.1.

[beikov]

Looks like a concurrency issue, but I have to think through this a bit to understand how this can happen.

[EugenMayer]

Thank you!