Janusgraph embedded multi instance(JVM) data sync issue

Pawan Shriwas

Hi All,

I am facing one problem for synchronization of data stored between multiple embedded mode janusgraph instances.

If we are creating some data into graph using JVM 1 and after committing when we get same data from JVM 2 its not reflecting for some duration.

I want to avail the same information to all instances after any CRUD operation once it gets committed.

I am using the same graph property in all instances of embedded janusgraph.

cache.db-cache = true
cache.db-cache-clean-wait = 20
cache.db-cache-time = 180000
cache.db-cache-size = 0.25
query.batch = true = true
query.batch-property-prefetch = true
######################property file end############################

Please let me know if someone faces this and how to prevent this. 


Re: Slowing of janusgraph


Hmm, these figures seem perfectly reasonable. It seems I was also wrong about the db-cache heap region not being shared between graphs. So you have to gather more information about was is going wrong. Some ideas:

  1. does restarting nginx make a difference? Communication between JanusGraph server and gremlin clients runs over websockets. Make sure there is no issue with communication channels kept occupied.
  2. This thread gives an nginx setup using a DNS virtual IP address. Possibly this makes a difference in websocket communication issues.
  3. disable the db-cache and see if this make a difference (this can only make a difference if there are many clients with transaction caches)
  4. check the logs of janusgraph server for other indications

Best wishes,      Marc

Re: Can I use spark computer on CQL without hadoop cluster


It is also possible to run spark on kubernetes (in combination with distributed storage like S3 or minio):

It will require some time to get your head around this, but note that you can do this with or without the spark operator installed on your kubernetes cluster.


Re: Can I use spark computer on CQL without hadoop cluster

Boxuan Li

Hi Pawan,

Do you want to run Spark traversal on a Spark standalone cluster rather than a Hadoop Yarn cluster? In that case, you could follow the JanusGraph documentation or check out this guide on Medium.


Can I use spark computer on CQL without hadoop cluster

Pawan Shriwas

Hi All,

I am checking the possibility of using a graph computer using spark on CQL backend without hadoop installation.

Please let me know if we can do this and how can i achieve this. I don't want to introduce hadoop cluster just because of this use case. I will appreciate  if anyone can share some resources around it.

Re: Slowing of janusgraph


Hi Thanks Marc for the quick reply, below are the details you asked.

Max. Heap Size (Estimated): 3.85G

No of graphs: 7 to 8

       cache.db-cache = true
       cache.db-cache-clean-wait = 20
       cache.db-cache-time = 180000
       cache.db-cache-size = 0.5

Re: Slowing of janusgraph


Have you tried to increase JVM memory settings for JanusGraph Server? Also, check the settings for the database cache size, because I tend to remember that each graph has its own cache. Can you provide some numbers: number of graphs, database cache settings, JVM memory settings, etc.

Best wishes,    Marc

Slowing of janusgraph


Hi, i've three janusgraph (0.5.3) servers pointing to same bigTable with same configurations mentioned below. 

I'm using ConfigurationManagementGraph, below is the properties file





cache.db-cache = true
cache.db-cache-clean-wait = 20
cache.db-cache-time = 180000
cache.db-cache-size = 0.5


And gremlin-server.yaml file looks like this

port: 8182
scriptEvaluationTimeout: 100000
channelizer: org.janusgraph.channelizers.JanusGraphWebSocketChannelizer
graphs: {
  graph: conf/,
  ConfigurationManagementGraph: conf/
scriptEngines: {
  gremlin-groovy: {
    plugins: { org.janusgraph.graphdb.tinkerpop.plugin.JanusGraphGremlinPlugin: {},
               org.apache.tinkerpop.gremlin.server.jsr223.GremlinServerGremlinPlugin: {},
               org.apache.tinkerpop.gremlin.tinkergraph.jsr223.TinkerGraphGremlinPlugin: {},
               org.apache.tinkerpop.gremlin.jsr223.ImportGremlinPlugin: {classImports: [java.lang.Math], methodImports: [java.lang.Math#*]},
               org.apache.tinkerpop.gremlin.jsr223.ScriptFileGremlinPlugin: {files: [scripts/empty-sample.groovy]}


All the servers are sharing the same configurations. Now i've setup a nginx also on top of these servers. So, when I've to create a graph I create a connection first with nginx and nginx connects with the most available janusgraph server and that server creates a graph for me and stores it in the bigTable. 
I can now access this graph from any of the three servers.

Till now everything is working as expected.

Issue1:  Slowing of Servers

everyday I generate a new graph with around 150K vertex and 250K edges. For the first time servers generate the graph but later on it slows down the execution and at one moment it stops completely. It wont process anything it, gets stuck in between and don't take any request. So to solve this i've to restart the servers everytime. Which leads to second issue

Issue2: Deleting of graphs

Like when servers are running (all of them). In that time if a graph is created then I can also delete it. But the moment i restart any of the server then i'm not able to delete the graph, the server which get restarted continuously throws error "Table Not Found". So to resolve this too, I've to stop all the servers first and delete all the graph from bigtable then restart the servers again. But again after first graph creation by all the servers, it leads to Issue1 again.

Re: Failure on mvn clean install


Thanks for reporting. Somehow, the tests for janusgraph-examples do not pass anymore when run in a stand-alone fashion (these tests are also run in the CI from the main pom.xml in , where obviously they do pass). I reported an issue for this.

If you just want to run the examples you can build the jar with:
mvn clean install -DskipTests
Best wishes,     Marc

Re: Potential transaction issue (JG 0.6.0)

Boxuan Li

I guess this has something to do with race conditions. Although I couldn't reproduce the exact issue, I found a similar race condition that caused an NPE in `expireSchemaElement` method (  The fix is here: which will be released in the next minor version (0.6.1). This PR also includes the temporary fix proposed by Sergey:

public InternalVertex getInternalVertex(long vertexId) {
// TODO temporary fix
if (isClosed()) {
return null;
//return vertex but potentially check for existence
return vertexCache.get(vertexId, internalVertexRetriever);

If anyone is able to find a steady way to reproduce this issue and/or encounter a similar NPE issue somewhere else, please let me know, thanks! A code review is also very welcome.


Failure on mvn clean install


Just unpacked and got the server started with ./bin/ console. It started up fine. Then I cd to the examples directory and to a mvn clean install. I get the following errors
[ERROR] Failures: 
[ERROR]   GraphAppTest.openGraphConfigNotFound:70 Unexpected exception type thrown ==> expected: <> but was: <org.apache.commons.configuration2.ex.ConfigurationException>
[ERROR]   GraphAppTest.openGraphNullConfig:65 Unexpected exception type thrown ==> expected: <java.lang.NullPointerException> but was: <java.lang.RuntimeException>
[ERROR] Tests run: 7, Failures: 2, Errors: 0, Skipped: 0
[INFO] ------------------------------------------------------------------------
[INFO] Reactor Summary for JanusGraph-Examples: Examples for JanusGraph 0.6.0:
[INFO] JanusGraph-Examples: Examples for JanusGraph ....... SUCCESS [  2.603 s]
[INFO] Example-Common: Common Graph Code for Examples ..... FAILURE [  6.387 s]
[INFO] Example-BerkeleyJE: BerkeleyJE Storage, Lucene Index SKIPPED
[INFO] Example-Cql: Cassandra CQL Storage, Elasticsearch Index SKIPPED
[INFO] Example-HBase: HBase Storage, Solr Index ........... SKIPPED
[INFO] Example-RemoteGraph: Example with RemoteGraph ...... SKIPPED
[INFO] Example-TinkerGraph: Example with TinkerGraph ...... SKIPPED
[INFO] ------------------------------------------------------------------------
[INFO] -----------------------------------------------
Any ideas how to fix that?
I've been trying to setup JanusGraph all day and can't seem to figure it out!

Re: Parameterized bulk insert (addV) script in gremlin-python

Scott Friedman

Wow, works like a charm using gremlin-python, and I don't even have to use a script!

Thanks for the quick wisdom!


Re: Parameterized bulk insert (addV) script in gremlin-python


Hi Scott,

You can try to use this thread for inspiration:

2 1/2 years ago I was impressed by this solution! This really iterates over the input data and add multiple vertices.

Best wishes,   Marc

Parameterized bulk insert (addV) script in gremlin-python

Scott Friedman

Good afternoon,

I'm attempting to use gremlin-python to do bulk vertex or edge inserts, and I'd figured I could use params to send in a simple script.  A simple proof of concept would be:

cmd = 'g.addV().property("name", values)'
params = { 'values': ['name1', 'name2'] }
result_set = conn._client.submit(cmd, params)

...but when I execute that, I get a single vertex added with "[name1, name2]" as its name.  I suppose this makes sense.  And is there a way to issue a compact loop-based script over an arbitrary list in my parameters?

I could always forego the script-based approach and use the python API to make a massive query of repeated addV() calls (which is my present implementation), but I'd hoped that a parameter-based, script-based solution would be more efficient (and elegant).

Suggestions are very welcome!


Re: JG as a 3store, rdf support

Matthew Nguyen <nguyenm9@...>

Thanks Marc, hadn't seen ERGS but looks interesting and will take a look.  

Re: Using a user-supplied string as vertex ID

Scott Friedman

Thanks, Boxuan!  Looks like a great discussion in that github issue; I hope something eventually comes of it!

Re: Python output to mgmt queries


Hi Marc, 
Thank you for your reply. I would like to access this information only from the schema (my graph is empty now). Your second solution could work but it only prints the result. So to get the labels, I would need to extract them with some regex. 
However, I think I have found a solution.
It seems that python converts the object org.janusgraph.graphdb.types.VertexLabelVertex to gremlin_python.structure.graph.Vertex. I do not know if this is wanted or accidental  (for janusgraph-0.6.x with gremlin_python-3.5.1).
However, I can get a list of labels if I convert the labels to string before requesting the result to Python. 
For example
from gremlin_python.driver.client import Client
client = Client('ws://localhost:8182/gremlin', 'mygraph')
mgmt = "mygraph.openManagement()"
get_v_labels = mgmt + ".getVertexLabels().collect {a ->}"

In this way, I can also get properties etc.

Thanks again and best wishes, 

Re: JG as a 3store, rdf support


Hi Matthew,

Not an answer to your questions, but a few remarks that might help anyway:
  • while a single client has its limits in adding vertices and edges, people use distributed computing frameworks such as Apache Spark and the like, to increase overall ingestion rates
I could not help doing a singe Google search request myself and hit upon:
which seems pretty recent, though immature.

Best wishes,   Marc

Re: Python output to mgmt queries


I am not sure what you are up to and the API changes in remote connections may have confused you.

If you want to see the labels of all vertices in the graph (for janusgraph-0.6.x with gremlin_python-3.5.1):
from gremlin_python.process.anonymous_traversal import traversal
g = traversal().withRemote(DriverRemoteConnection('ws://localhost:8182/gremlin','g'))
If you want to see the vertex labels that you defined in the JanusgGraph schema:
from gremlin_python.driver.client import Client
client = Client('ws://localhost:8182/gremlin', 'graph')
for line in client.submit("graph.openManagement().printSchema()").next():
Best wishes,    Marc

Re: Using a user-supplied string as vertex ID

Boxuan Li

Hi Scott,

Currently, JanusGraph does not support user-specified string identifiers. You could check out to see discussions on this topic.


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