Neo4j Bug in Tinkerpop3

[potera...@gmail.com]

Hi Guys,

I think I've found a bug in the Neo4j implementation for T3.

Please run the following test:

    

    @Test

    public void neo4jPropertyBug2(){

    Configuration config = new BaseConfiguration();

    config.addProperty("gremlin.neo4j.metaProperties", true);

        config.addProperty("gremlin.neo4j.multiProperties", true);

        config.addProperty("gremlin.neo4j.directory", "neo4jdbBug");

        

        Neo4jGraph neo4jGraph = Neo4jGraph.open(config); 

        

        Vertex v = neo4jGraph.addVertex("prop", "abc");

        VertexProperty<String> prop = v.property("prop");

        assertTrue(Property.empty().equals(prop.property("some-missing-meta-prop")));

    }

I would normally expect the above test to pass. However, it fails with the following stack trace:

java.lang.NullPointerException

at com.tinkerpop.gremlin.neo4j.structure.Neo4jVertexProperty.property(Neo4jVertexProperty.java:121)

at com.itc.graph.structure.Neo4jTest.neo4jPropertyBug(Neo4jTest.java:29)

Please have a look at method Neo4jVertexProperty.property:

    public <U> Property<U> property(final String key) {

        if (!this.vertex.graph.supportsMetaProperties)

            throw VertexProperty.Exceptions.metaPropertiesNotSupported();

        this.vertex.graph.tx().readWrite();

        try {

            if (this.node.hasProperty(key))

                return new Neo4jProperty<>(this, key, (U) this.node.getProperty(key));

            else

                return Property.empty();

        } catch (IllegalStateException | NotFoundException ex) {

            throw Element.Exceptions.elementAlreadyRemoved(this.getClass(), this.id());

        }

    }

It calls this.node.hasProperty(key), and since this.node is null (no meta-property added on the vertex property yet), it raises a NullPointerException.

I suppose the above code should do something like:

         if (isNode() && this.node.hasProperty(key)) { ....

Cheers,

Cosmin.

[Stephen Mallette]

Thanks for finding this.  It identified a bug as well as a hole in our test suite.  It has been corrected as you suggested:

https://github.com/apache/incubator-tinkerpop/commit/50f298bb0e1f2a239dc212e58c09311482f0516f

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[potera...@gmail.com]

Hi Stephen,

Thanks for fixing it.

Cheers,
Cosmin

[drVillo]

Bumping up this thread. I'm encountering a similar issue when attempting to use subgraph() on Neo4j (the same statement works using the Tinkergraph).

This happens running gremlin-console-3.2.0-incubating, which from what I see uses the fix above.

Thanks

F

Trace below

----------------

gremlin> g.V(33772442).valueMap()

==>[profileId:[101276158], siteId:[10]]

gremlin> sg = g.V(33772442).outE().subgraph('sg').cap('sg').next()

Properties on a vertex property is not supported

Display stack trace? [yN] y

java.lang.UnsupportedOperationException: Properties on a vertex property is not supported

at org.apache.tinkerpop.gremlin.structure.VertexProperty$Exceptions.metaPropertiesNotSupported(VertexProperty.java:103)

at org.apache.tinkerpop.gremlin.neo4j.structure.trait.NoMultiNoMetaNeo4jTrait.getProperties(NoMultiNoMetaNeo4jTrait.java:146)

at org.apache.tinkerpop.gremlin.neo4j.structure.Neo4jVertexProperty.properties(Neo4jVertexProperty.java:97)

at org.apache.tinkerpop.gremlin.process.traversal.step.sideEffect.SubgraphStep.lambda$getOrCreate$2(SubgraphStep.java:102)

at java.util.Iterator.forEachRemaining(Iterator.java:116)

at org.apache.tinkerpop.gremlin.process.traversal.step.sideEffect.SubgraphStep.getOrCreate(SubgraphStep.java:100)

at org.apache.tinkerpop.gremlin.process.traversal.step.sideEffect.SubgraphStep.addEdgeToSubgraph(SubgraphStep.java:111)

at org.apache.tinkerpop.gremlin.process.traversal.step.sideEffect.SubgraphStep.sideEffect(SubgraphStep.java:64)

at org.apache.tinkerpop.gremlin.process.traversal.step.sideEffect.SideEffectStep.processNextStart(SideEffectStep.java:39)

at org.apache.tinkerpop.gremlin.process.traversal.step.util.AbstractStep.hasNext(AbstractStep.java:140)

at org.apache.tinkerpop.gremlin.process.traversal.step.util.ExpandableStepIterator.hasNext(ExpandableStepIterator.java:42)

at org.apache.tinkerpop.gremlin.process.traversal.step.util.SupplyingBarrierStep.processAllStarts(SupplyingBarrierStep.java:83)

at org.apache.tinkerpop.gremlin.process.traversal.step.util.SupplyingBarrierStep.processNextStart(SupplyingBarrierStep.java:70)

at org.apache.tinkerpop.gremlin.process.traversal.step.util.AbstractStep.next(AbstractStep.java:126)

at org.apache.tinkerpop.gremlin.process.traversal.step.util.AbstractStep.next(AbstractStep.java:37)

at org.apache.tinkerpop.gremlin.process.traversal.util.DefaultTraversal.next(DefaultTraversal.java:156)

...

[Stephen Mallette]

This looks like a different error to me (unrelated to the original thread). I just might see the problem, but not completely sure about it. Could you please create a more complete, simple example, with some basic sample data that replicates the problem? If I had a nice console session to work with I think it could be solved pretty quickly....maybe even create an issue in JIRA to track it given that this does look like a bug: https://issues.apache.org/jira/browse/TINKERPOP/

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[drVillo]

Agreed. I've been able to reproduce it with a test graph and created this ticket: https://issues.apache.org/jira/browse/TINKERPOP-1359

I like the idea of extracting subgraphs from the full database _a lot_. This will make analysis a lot more manageable for our BI team. Just so I know, how is your release schedule looking like?

Thanks!

F

[Stephen Mallette]

thanks for doing that. we are currently preparing for a release of 3.1.3 and 3.2.1 - we typically freeze code changes for a week before release and focus on test and documentation and that should start at the end of the day today. after that the community votes to release - so i would expect us to have those out the week of July 18th. 

i will try to figure out what's wrong with your bug so that the fix can go in to this release cycle.

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[drVillo]

thank you, appreciated:)

F

[drVillo]

Sorry to be a pain but I've pulled master in order to play with this change but I can't get the neo4j plugin installed... See below (executed from ./tinkerpop/gremlin-console/target/apache-gremlin-console-3.2.1-SNAPSHOT-standalone/bin

gremlin> :install org.apache.tinkerpop neo4j-gremlin 3.2.1-SNAPSHOT

log4j:WARN No appenders could be found for logger (org.apache.tinkerpop.gremlin.groovy.util.DependencyGrabber).

log4j:WARN Please initialize the log4j system properly.

log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.

==>Conflicting module versions. Module [groovy-swing is loaded in version 2.4.7 and you are trying to load version 2.4.6

I couldn't find a reference to 2.4.6 in the project's pom though.

Cheers

F 

[Stephen Mallette]

we just bumped to groovy 2.4.7 in the last week or so. not sure how you're building/installing but you gotta make sure all those versions line up. looks like you have some old jars hanging around. 

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[Robert Dale]

First, I recommend removing your grapes cache. On linux, rm -rf
~/.groovy/grapes
I actually ran into a problem with downloading scala-reflect and had
to clear my maven cache for it: rm -rf
~/.m2/repository/org/scala-lang/scala-reflect

If you have master checked out, this will recompile all necessary deps
with the correct groovy version and should get you going:

mvn clean install -Dmaven.test.skip=true -pl
gremlin-console,gremlin-core,gremlin-driver,gremlin-groovy,gremlin-groovy-test,gremlin-server,gremlin-shaded,gremlin-test,neo4j-gremlin,tinkergraph-gremlin

unzip gremlin-console/target/apache-gremlin-console-3.2.1-SNAPSHOT-distribution.zip
cd apache-gremlin-console-3.2.1-SNAPSHOT/
./bin/gremlin.sh
:install org.apache.tinkerpop neo4j-gremlin 3.2.1-SNAPSHOT
(restart console)
:plugin use tinkerpop.neo4j

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>
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Robert Dale

[drVillo]

Cleaning up ~/.groovy/grapes did the trick, thanks!

[Stephen Mallette]

pesky grapes.....

note you can build with: 

mvn clean install -DcleanGrapes 

if you have a standard .groovy grapes dir

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