Unable to compile with tests on openjdk 21.0.10 and openjdk 8

[mrckzgl]

Please include configurations and logs if available.

For confirmed bugs, please report:

• Version: b424a8f
• Storage Backend: inmemory
• Mixed Index Backend: does not matter
• Expected Behavior: mvn clean install should execute without errors on master branch
• Current Behavior: see below
• Steps to Reproduce: execute mvn clean install on master branch

Running mvn clean install on current master branch results in inmemory tests to fail:

INFO] Results:
[INFO] 
[ERROR] Errors: 
[ERROR]   InMemoryCustomIdTest>JanusGraphCustomIdTest.testWriteAndReadWithJanusGraphIoRegistryWithGryo:576->JanusGraphCustomIdTest.testWritingAndReading:626 » IllegalArgument Unable to create serializer "org.apache.tinkerpop.shaded.kryo.serializers.FieldSerializer" for class: java.util.concurrent.atomic.AtomicLong
[ERROR]   InMemoryGraphTest>JanusGraphTest.testWriteAndReadWithJanusGraphIoRegistryWithGryo:8664->JanusGraphTest.testWritingAndReading:8679 » IllegalArgument Unable to create serializer "org.apache.tinkerpop.shaded.kryo.serializers.FieldSerializer" for class: java.util.concurrent.atomic.AtomicLong
[ERROR]   InMemoryLazyLoadGraphTest>JanusGraphTest.testWriteAndReadWithJanusGraphIoRegistryWithGryo:8664->JanusGraphTest.testWritingAndReading:8679 » IllegalArgument Unable to create serializer "org.apache.tinkerpop.shaded.kryo.serializers.FieldSerializer" for class: java.util.concurrent.atomic.AtomicLong
[INFO] 
[ERROR] Tests run: 549, Failures: 0, Errors: 3, Skipped: 83
[INFO] 
[INFO] ------------------------------------------------------------------------
[INFO] Reactor Summary for JanusGraph: Distributed Graph Database 1.2.0-SNAPSHOT:
[INFO] 
[INFO] JanusGraph: Distributed Graph Database ............. SUCCESS [ 17.109 s]
[INFO] JanusGraph-gRPC: gRPC Components for JanusGraph .... SUCCESS [  6.101 s]
[INFO] JanusGraph-Driver: Gremlin-Driver Library for JanusGraph SUCCESS [ 19.645 s]
[INFO] JanusGraph-Core: Core Library for JanusGraph ....... SUCCESS [ 28.363 s]
[INFO] JanusGraph-Backend-testutils: Collection of Backend tests SUCCESS [  8.210 s]
[INFO] JanusGraph-InMemory: InMemory Backend for JanusGraph FAILURE [04:01 min]
[INFO] JanusGraph-Server: Server Components for JanusGraph  SKIPPED
[INFO] JanusGraph-Test: Test Suite for JanusGraph ......... SKIPPED
[INFO] JanusGraph-BerkeleyJE: Distributed Graph Database .. SKIPPED

relevant stack trace of one of the tests:

[ERROR] Tests run: 204, Failures: 0, Errors: 1, Skipped: 41, Time elapsed: 53.53 s <<< FAILURE! -- in org.janusgraph.graphdb.inmemory.InMemoryGraphTest
[ERROR] org.janusgraph.graphdb.inmemory.InMemoryGraphTest.testWriteAndReadWithJanusGraphIoRegistryWithGryo(Path) -- Time elapsed: 0.209 s <<< ERROR!
java.lang.IllegalArgumentException: Unable to create serializer "org.apache.tinkerpop.shaded.kryo.serializers.FieldSerializer" for class: java.util.concurrent.atomic.AtomicLong
	at org.apache.tinkerpop.shaded.kryo.factories.ReflectionSerializerFactory.makeSerializer(ReflectionSerializerFactory.java:67)
	at org.apache.tinkerpop.shaded.kryo.factories.ReflectionSerializerFactory.makeSerializer(ReflectionSerializerFactory.java:45)
	at org.apache.tinkerpop.shaded.kryo.Kryo.newDefaultSerializer(Kryo.java:380)
	at org.apache.tinkerpop.shaded.kryo.Kryo.getDefaultSerializer(Kryo.java:364)
	at org.apache.tinkerpop.gremlin.structure.io.gryo.GryoTypeReg.registerWith(GryoTypeReg.java:122)
	at org.apache.tinkerpop.gremlin.structure.io.gryo.GryoMapper.createMapper(GryoMapper.java:101)
	at org.apache.tinkerpop.gremlin.structure.io.gryo.GryoMapper.createMapper(GryoMapper.java:75)
	at org.apache.tinkerpop.gremlin.structure.io.gryo.GryoWriter.<init>(GryoWriter.java:52)
	at org.apache.tinkerpop.gremlin.structure.io.gryo.GryoWriter.<init>(GryoWriter.java:48)
	at org.apache.tinkerpop.gremlin.structure.io.gryo.GryoWriter$Builder.create(GryoWriter.java:183)
	at org.apache.tinkerpop.gremlin.process.traversal.step.sideEffect.IoStep.constructWriter(IoStep.java:190)
	at org.apache.tinkerpop.gremlin.process.traversal.step.sideEffect.IoStep.write(IoStep.java:121)
	at org.apache.tinkerpop.gremlin.process.traversal.step.sideEffect.IoStep.processNextStart(IoStep.java:112)
	at org.apache.tinkerpop.gremlin.process.traversal.step.util.AbstractStep.hasNext(AbstractStep.java:155)
	at org.apache.tinkerpop.gremlin.process.traversal.step.util.ExpandableStepIterator.next(ExpandableStepIterator.java:55)
	at org.apache.tinkerpop.gremlin.process.traversal.step.filter.FilterStep.processNextStart(FilterStep.java:40)
	at org.apache.tinkerpop.gremlin.process.traversal.step.util.AbstractStep.next(AbstractStep.java:140)
	at org.apache.tinkerpop.gremlin.process.traversal.step.util.AbstractStep.next(AbstractStep.java:40)
	at org.apache.tinkerpop.gremlin.process.traversal.Traversal.iterate(Traversal.java:210)
	at org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.GraphTraversal.iterate(GraphTraversal.java:4005)
	at org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.GraphTraversal$Admin.iterate(GraphTraversal.java:241)
	at org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.DefaultGraphTraversal.iterate(DefaultGraphTraversal.java:48)
	at org.janusgraph.graphdb.JanusGraphTest.testWritingAndReading(JanusGraphTest.java:8679)
	at org.janusgraph.graphdb.JanusGraphTest.testWriteAndReadWithJanusGraphIoRegistryWithGryo(JanusGraphTest.java:8664)
	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1596)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1596)
Caused by: java.lang.reflect.InvocationTargetException
	at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:502)
	at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:486)
	at org.apache.tinkerpop.shaded.kryo.factories.ReflectionSerializerFactory.makeSerializer(ReflectionSerializerFactory.java:54)
	... 26 more
Caused by: java.lang.reflect.InaccessibleObjectException: Unable to make field private volatile long java.util.concurrent.atomic.AtomicLong.value accessible: module java.base does not "opens java.util.concurrent.atomic" to unnamed module @25d250c6
	at java.base/java.lang.reflect.AccessibleObject.throwInaccessibleObjectException(AccessibleObject.java:391)
	at java.base/java.lang.reflect.AccessibleObject.checkCanSetAccessible(AccessibleObject.java:367)
	at java.base/java.lang.reflect.AccessibleObject.checkCanSetAccessible(AccessibleObject.java:315)
	at java.base/java.lang.reflect.Field.checkCanSetAccessible(Field.java:183)
	at java.base/java.lang.reflect.Field.setAccessible(Field.java:177)
	at org.apache.tinkerpop.shaded.kryo.serializers.FieldSerializer.buildValidFields(FieldSerializer.java:306)
	at org.apache.tinkerpop.shaded.kryo.serializers.FieldSerializer.rebuildCachedFields(FieldSerializer.java:239)
	at org.apache.tinkerpop.shaded.kryo.serializers.FieldSerializer.rebuildCachedFields(FieldSerializer.java:182)
	at org.apache.tinkerpop.shaded.kryo.serializers.FieldSerializer.<init>(FieldSerializer.java:155)
	... 29 more

This is on openjdk 21.0.10 2026-01-20.

[mrckzgl]

Probably related to: https://issues.apache.org/jira/browse/TINKERPOP-2859
Tried to run mvn install -Dsurefire.jvmArgs="--illegal-access=permit" but that didn't do the trick ...

[mrckzgl]

Trying to compile with JAVA 8 gets me until

[INFO] Results:
[INFO] 
[ERROR] Failures: 
[ERROR]   IDPoolTest.testAllocationTimeoutAndRecovery:183 
  Unexpected method calls:
    EasyMock for interface org.janusgraph.diskstorage.IDAuthority -> IDAuthority.getIDBlock(42 (int), 777 (int), PT1S)
[INFO] 
[ERROR] Tests run: 970, Failures: 1, Errors: 0, Skipped: 0
[INFO] 

-------------------------------------------------------------------------------
Test set: org.janusgraph.graphdb.idmanagement.IDPoolTest
-------------------------------------------------------------------------------
Tests run: 7, Failures: 1, Errors: 0, Skipped: 0, Time elapsed: 15.09 s <<< FAILURE! -- in org.janusgraph.graphdb.idmanagement.IDPoolTest
org.janusgraph.graphdb.idmanagement.IDPoolTest.testAllocationTimeoutAndRecovery -- Time elapsed: 2.045 s <<< FAILURE!
java.lang.AssertionError: 

  Unexpected method calls:
    EasyMock for interface org.janusgraph.diskstorage.IDAuthority -> IDAuthority.getIDBlock(42 (int), 777 (int), PT1S)
	at org.easymock.internal.MocksControl.verify(MocksControl.java:264)
	at org.janusgraph.graphdb.idmanagement.IDPoolTest.testAllocationTimeoutAndRecovery(IDPoolTest.java:183)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at java.util.ArrayList.forEach(ArrayList.java:1259)
	at java.util.ArrayList.forEach(ArrayList.java:1259)

[porunov]

TinkerPop (our upstream library) officially compatible with JDK 11 & 17 for compilation, JanusGraph is currently compatible with JDK 8 & 11 for compilation. For runtime I can confirm that JanusGraph works on JRE 24 as a standalone library, but if you want to run a standard Gremlin Server - Gremlin Server will fail as it's only compatible with Java 11 & 17.
Moreover, if you use janusgraph-hadoop that depends on spark-gremlin - you probably won't be able to run that dependency on modern Java.

That said, we have strong intentions on bringing modern Java 25 support into JanusGraph. To accomplish this, we first need to add Java 25 support to TinkerPop 4.0.0 (see PR apache/tinkerpop#3489). After which we age going to drop Java 8 and Java 11 support from JanusGraph completely (other than janusgraph-driver which is only a client library) and release JanusGraph that will be running on JRE 25 by default with enabled Virtual Threads.
This upgrade will bring both higher throughput and lower resources utilization to JanusGraph due to unbound default virtual threads.

JanusGraph will support: Java 17, Java 21, Java 25 versions after that. However, for now - there is no point of adding partial Java 21 support to some of JanusGraph modules as we won't be able to migrate all modules without first upgrading to TinkerPop 4.0.0.

---

Regarding your compilation attempts - you are executing tests right now.
I suggest reading BUILDING.md on how to build JanusGraph as well as prerequisites.

Depending on how you want to build JanusGraph, you may want to simply compile classes:

mvn clean install -DskipTests=true

Or you may want to actually build re-usable distribution artifact:

mvn clean install -Pjanusgraph-release -Dgpg.skip=true -DskipTests=true