Multithreaded use of session.save() results in relationships being wrongly deleted

When saving a new entity linked to an existing entity using session.save() it results in the relationship being first saved and then deleted when multiple threads are executing session.save() in parallel.

I wrote a test to showcase the issue here.

I’m only saving new nodes and relationships, however I’m seeing a lot of logs indicating deletion:

DEBUG org.neo4j.ogm.context.EntityGraphMapper: 155 - context-del: ($1300)-[null:VIDEO_DESCRIBES_VIDEO_ASSET]->($1296)

that gets translated to

UNWIND {rows} as row MATCH (startNode) WHERE ID(startNode) = row.startNodeId MATCH (endNode) WHERE ID(endNode) = row.endNodeId MATCH (startNode)-[rel:VIDEO_DESCRIBES_VIDEO_ASSET]->(endNode) DELETE rel

[kjkrum]

IMO, this information should be included in the Javadoc for Session.

[vince-bickers]

In a web context you should override the Session bean in your Configuration class. You can then apply scoping annotation to scope the OGM session either to a client’s HttpSession, or to each individual HttpRequest. For example.

   // http-session scope
    @Bean
    @Scope(value = "session", proxyMode = ScopedProxyMode.TARGET_CLASS)
    public Session getSession() throws Exception {
        return super.getSession();
    }

   // http-request scope
    @Bean
    @Scope(value = "request", proxyMode = ScopedProxyMode.TARGET_CLASS)
    public Session getSession() throws Exception {
        return super.getSession();
    }