Concerning warnings about missing classes when using JanusGraph 1.0.0 with CQL in embedded mode #4363
Comments
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I am also facing similar warnings with Hbase. Although i have verified that they do not cause issues in actual working of the code but still feels like this might be an issue. |
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See also #4359 |
Discussed in #4349
Originally posted by pete-gillin-privitar March 27, 2024
We are using JanusGraph in embedded mode with the CQL backend. On upgrading to JanusGraph 1.0.0, we are getting some concerning warnings about missing classes when we do our first traversal. I am not sure whether I should be worried about these, or what combination of maven dependencies (and possibly exclusions?) I need to get rid of them.
I can reproduce this by doing anything which causes the class
JanusGraphTraverserUtilto be loaded, in a maven project withorg.janusgraph:janusgraph-coreandorg.janusgraph:janusgraph-cqlas dependencies. I am providing the full text of the warnings and a minimal standalone reproduction below, but I'll summarize quickly here.We have a dependency on
janusgraph-cqlbut not onjanusgraph-hadoop. That means that we haveorg.janusgraph.hadoop.scan.CQLHadoopScanRunneron the classpath, but notorg.janusgraph.hadoop.scan.AbstractHadoopScanRunnerwhichCQLHadoopScanRunnerextends. That means that we'll never be able to load the classCQLHadoopScanRunner. That doesn't seem to matter in itself, since (in our testing so far) we have not hit a code path which actually uses that class. However, the first time we do a traversal, the static initializer oforg.janusgraph.graphdb.util.JanusGraphTraverserUtiluses theReflectionsutility to scan every class underorg.janusgraph, and that tries to expand the supertypes, and that logs a warningcould not get type for name org.janusgraph.hadoop.scan.AbstractHadoopScanRunner from any class loader.We get a similar story for a few other classes (see the below). As well as several from
janusgraph-hadoop, this includes one inorg.apache.hadoop:hadoop-mapreduce-client-core, and one inorg.apache.tinkerpop:gremlin-server.The upgrade instructions contain this note, which seems potentially relevant:
However, that makes no difference that I can tell. In my reproduction below, I put
in the
janusgraph-cqldependency in mypom.xmland nothing changed. I assume that this is because the classes likeCQLHadoopScanRunnerare injanusgraph-cql, not incassandra-hadoop-util.In my toy reproduction, I can make these warnings go away by adding dependencies on
janusgraph-hadoopandgremlin-server. In my real application, addingjanusgraph-hadoopcauses a different problem (to do with Spring initialization). I can try to debug that if adding this dependency is the correct thing to do, but I'd like confirmation that this really is the correct approach. We're not using Hadoop to the best of my knowledge, so being forced to add thejanusgraph-hadoopdependency would feel like an odd thing to do.Alternatively, we could ignore the warnings, or we could even repackage the
janusgraph-cqlJAR to exclude the classes with missing superclasses. But I'd like confirmation that this is going to be safe — I don't know whether they'd be used on some code path that we just haven't happened to hit in our testing so far. (Repackaging the JAR would also seem like an odd thing to do.)Any advice on how to proceed would be very welcome! Thanks.
Full text of warnings:
Standalone reproduction:
In
src/main/java/com/example/Repro.javaI have:In
pom.xmlI have:And then I do
mvn clean compile exec:java -Dexec.mainClass=com.example.Reproto get the output shown above.The text was updated successfully, but these errors were encountered: