Gremlin-Python in JanusGraph

[john.h...@redjack.com]

Gentlemen and Ladies,

Thank you for your help with the previous difficulties that we have been having in configuring our system.  We have recently gotten JanusGraph running in Server mode with HBase, and it is working correctly.  However, we have recently tried to add gremlin-python access to the server, so that we can work with it via a python client.

We are following the instructions on this page, which we have established work correctly when interfacing with GremlinServer running TinkerGraph: http://tinkerpop.apache.org/docs/current/reference/#gremlin-python

The problem is that when running starting the JanusGraph server referencing the following file:

host: localhost

port: 8182

threadPoolWorker: 1

gremlinPool: 8

scriptEvaluationTimeout: 30000

graphs: {

  graph: conf/tinkergraph-empty.properties}

scriptEngines: {

  gremlin-groovy: {

    plugins: { org.apache.tinkerpop.gremlin.server.jsr223.GremlinServerGremlinPl

ugin: {},

               org.apache.tinkerpop.gremlin.tinkergraph.jsr223.TinkerGraphGremli

nPlugin: {},

               org.apache.tinkerpop.gremlin.jsr223.ImportGremlinPlugin: {classIm

ports: [java.lang.Math], methodImports: [java.lang.Math#*]},

               org.apache.tinkerpop.gremlin.jsr223.ScriptFileGremlinPlugin: {fil

es: [scripts/generate-modern.groovy]}}},

  gremlin-jython: {},

  gremlin-python: {}

}

serializers:

  - { className: org.apache.tinkerpop.gremlin.driver.ser.GryoMessageSerializerV1

d0, config: { ioRegistries: [org.apache.tinkerpop.gremlin.tinkergraph.structure.

TinkerIoRegistryV1d0] }}            # application/vnd.gremlin-v1.0+gryo

  - { className: org.apache.tinkerpop.gremlin.driver.ser.GryoLiteMessageSerializ

erV1d0, config: { ioRegistries: [org.apache.tinkerpop.gremlin.tinkergraph.struct

ure.TinkerIoRegistryV1d0] }}        # application/vnd.gremlin-v1.0+gryo-lite

  - { className: org.apache.tinkerpop.gremlin.driver.ser.GryoMessageSerializerV1

d0, config: { serializeResultToString: true }}        # application/vnd.gremlin-

v1.0+gryo-stringd

  - { className: org.apache.tinkerpop.gremlin.driver.ser.GraphSONMessageSerializ

erGremlinV1d0, config: { ioRegistries: [org.apache.tinkerpop.gremlin.tinkergraph

.structure.TinkerIoRegistryV1d0] }} # application/vnd.gremlin-v1.0+json

  - { className: org.apache.tinkerpop.gremlin.driver.ser.GraphSONMessageSerializ

erGremlinV2d0, config: { ioRegistries: [org.apache.tinkerpop.gremlin.tinkergraph

.structure.TinkerIoRegistryV2d0] }} # application/vnd.gremlin-v2.0+json

  - { className: org.apache.tinkerpop.gremlin.driver.ser.GraphSONMessageSerializ

erV3d0, config: { ioRegistries: [org.apache.tinkerpop.gremlin.tinkergraph.struct

ure.TinkerIoRegistryV1d0] }}        # application/json

metrics: {

  slf4jReporter: {enabled: true, interval: 180000}}

strictTransactionManagement: false

threadPoolBoss: 1

maxInitialLineLength: 4096

maxHeaderSize: 8192

maxChunkSize: 8192

maxContentLength: 65536

maxAccumulationBufferComponents: 1024

resultIterationBatchSize: 64

or this file:

host: localhost

port: 8182

scriptEvaluationTimeout: 30000

channelizer: org.apache.tinkerpop.gremlin.server.channel.WebSocketChannelizer

graphs: {

  graph: conf/gremlin-server/janusgraph-hbase-server.properties}

plugins:

  - janusgraph.imports

scriptEngines: {

  gremlin-groovy: {

    imports: [java.lang.Math],

    staticImports: [java.lang.Math.PI],

    scripts: [scripts/empty-sample.groovy]},
  gremlin-jython: {},

  gremlin-python: {}}

serializers:

  - { className: org.apache.tinkerpop.gremlin.driver.ser.GryoMessageSerializerV1d0, config: { bufferSize: 8192, ioRegistries: [org.janusgraph.graphdb.tinkerpop.JanusGraphIoRegistry] }}

  - { className: org.apache.tinkerpop.gremlin.driver.ser.GryoLiteMessageSerializerV1d0, config: {ioRegistries: [org.janusgraph.graphdb.tinkerpop.JanusGraphIoRegistry] }}

  - { className: org.apache.tinkerpop.gremlin.driver.ser.GryoMessageSerializerV1d0, config: { serializeResultToString: true }}

  - { className: org.apache.tinkerpop.gremlin.driver.ser.GraphSONMessageSerializerGremlinV1d0, config: { ioRegistries: [org.janusgraph.graphdb.tinkerpop.JanusGraphIoRegistry] }}

  - { className: org.apache.tinkerpop.gremlin.driver.ser.GraphSONMessageSerializerGremlinV2d0, config: { ioRegistries: [org.janusgraph.graphdb.tinkerpop.JanusGraphIoRegistry] }}

  - { className: org.apache.tinkerpop.gremlin.driver.ser.GraphSONMessageSerializerV1d0, config: { ioRegistries: [org.janusgraph.graphdb.tinkerpop.JanusGraphIoRegistry] }}

processors:

  - { className: org.apache.tinkerpop.gremlin.server.op.session.SessionOpProcessor, config: { sessionTimeout: 28800000 }}

  - { className: org.apache.tinkerpop.gremlin.server.op.traversal.TraversalOpProcessor, config: { cacheExpirationTime: 600000, cacheMaxSize: 1000 }}

metrics: {

  consoleReporter: {enabled: true, interval: 180000},

  csvReporter: {enabled: true, interval: 180000, fileName: /tmp/gremlin-server-metrics.csv},

  jmxReporter: {enabled: true},

  slf4jReporter: {enabled: true, interval: 180000},

  gangliaReporter: {enabled: false, interval: 180000, addressingMode: MULTICAST},

  graphiteReporter: {enabled: false, interval: 180000}}

maxInitialLineLength: 4096

maxHeaderSize: 8192

maxChunkSize: 8192

maxContentLength: 65536

maxAccumulationBufferComponents: 1024

resultIterationBatchSize: 64

writeBufferLowWaterMark: 32768

writeBufferHighWaterMark: 65536

ssl: {

  enabled: false}

They give this error:

Exception in thread "main" java.lang.IncompatibleClassChangeError: Implementing class

        at java.lang.ClassLoader.defineClass1(Native Method)

        at java.lang.ClassLoader.defineClass(ClassLoader.java:763)

        at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)

        at java.net.URLClassLoader.defineClass(URLClassLoader.java:467)

        at java.net.URLClassLoader.access$100(URLClassLoader.java:73)

        at java.net.URLClassLoader$1.run(URLClassLoader.java:368)

        at java.net.URLClassLoader$1.run(URLClassLoader.java:362)

        at java.security.AccessController.doPrivileged(Native Method)

        at java.net.URLClassLoader.findClass(URLClassLoader.java:361)

        at java.lang.ClassLoader.loadClass(ClassLoader.java:424)

        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335)

        at java.lang.ClassLoader.loadClass(ClassLoader.java:357)

        at org.apache.tinkerpop.gremlin.python.jsr223.GremlinJythonScriptEngine.<init>(GremlinJythonScriptEngine.java:86)

        at org.apache.tinkerpop.gremlin.python.jsr223.GremlinJythonScriptEngineFactory.getScriptEngine(GremlinJythonScriptEngineFactory.java:110)

        at org.apache.tinkerpop.gremlin.jsr223.DefaultGremlinScriptEngineManager.createGremlinScriptEngine(DefaultGremlinScriptEngineManager.java:420)

        at org.apache.tinkerpop.gremlin.jsr223.DefaultGremlinScriptEngineManager.getEngineByName(DefaultGremlinScriptEngineManager.java:215)

        at org.apache.tinkerpop.gremlin.groovy.engine.ScriptEngines.createScriptEngine(ScriptEngines.java:424)

        at org.apache.tinkerpop.gremlin.groovy.engine.ScriptEngines.reload(ScriptEngines.java:187)

        at org.apache.tinkerpop.gremlin.groovy.engine.GremlinExecutor.lambda$createScriptEngines$11(GremlinExecutor.java:408)

        at org.apache.tinkerpop.gremlin.groovy.engine.ScriptEngines.<init>(ScriptEngines.java:92)

        at org.apache.tinkerpop.gremlin.groovy.engine.GremlinExecutor.createScriptEngines(GremlinExecutor.java:404)

        at org.apache.tinkerpop.gremlin.groovy.engine.GremlinExecutor.<init>(GremlinExecutor.java:110)

        at org.apache.tinkerpop.gremlin.groovy.engine.GremlinExecutor.<init>(GremlinExecutor.java:74)

        at org.apache.tinkerpop.gremlin.groovy.engine.GremlinExecutor$Builder.create(GremlinExecutor.java:651)

        at org.apache.tinkerpop.gremlin.server.util.ServerGremlinExecutor.<init>(ServerGremlinExecutor.java:136)

        at org.apache.tinkerpop.gremlin.server.util.ServerGremlinExecutor.<init>(ServerGremlinExecutor.java:83)

        at org.apache.tinkerpop.gremlin.server.GremlinServer.<init>(GremlinServer.java:110)

        at org.apache.tinkerpop.gremlin.server.GremlinServer.main(GremlinServer.java:344)

I am not actually using gremlin-jython, so I did make sure to remove the gremlin-jython references from both files and test them as well.  The results are the same. My best guess is that there is an API for the plugins of gremlin-jython and gremlin-python that is not matching up with JanusGraph properly, but it is unclear how to fix this.  Would anyone have any ideas?

Note, I can connect to the gremlin server in python using gremlinclient, and I can send commands to the server using the standard gremlin console as a client, so the server is operational.

Gremlin-python is considerably easier to develop in and preferable, so does anyone know how to fix this?  Thank you for all your help!

[Jason Plurad]

Hi John, you probably installed the wrong version of gremlin-python plugin. If you're using JanusGraph 0.1.1, the TinkerPop version is 3.2.3. If you're building master from source, it has TinkerPop 3.2.5 now.

Try this:

cd janusgraph-0.1.1-hadoop2
rm -rf ext/gremlin-python/
bin/gremlin-server.sh -i org.apache.tinkerpop gremlin-python 3.2.3

-- Jason

[john.h...@redjack.com]

Thank you Jason, that fixed the problem!