JanusGraphVertexFeatures#getCardinality (https://github.com/JanusGraph/janusgraph/blob/2c71b378339a3ab49b961eef29b5a042d018f513/janusgraph-core/src/main/java/org/janusgraph/graphdb/tinkerpop/JanusGraphFeatures.java#L161-L169).StandardJanusGraphTx transaction is created when checking a vertex property's cardinality (https://github.com/JanusGraph/janusgraph/blob/2c71b378339a3ab49b961eef29b5a042d018f513/janusgraph-core/src/main/java/org/janusgraph/graphdb/tinkerpop/JanusGraphFeatures.java#L162).CaffeineVertexCache (https://github.com/JanusGraph/janusgraph/blob/2c71b378339a3ab49b961eef29b5a042d018f513/janusgraph-core/src/main/java/org/janusgraph/graphdb/transaction/StandardJanusGraphTx.java#L335).CaffeineVertexCache internally creates a NonBlockingHashMap (https://github.com/JanusGraph/janusgraph/blob/master/janusgraph-core/src/main/java/org/janusgraph/graphdb/transaction/vertexcache/CaffeineVertexCache.java#L44) which initial size is configured in the GraphDatabaseConfiguration class or the graph configuration (https://github.com/JanusGraph/janusgraph/blob/2c71b378339a3ab49b961eef29b5a042d018f513/janusgraph-core/src/main/java/org/janusgraph/graphdb/configuration/GraphDatabaseConfiguration.java#L1613-L1620).NonBlockingHashMap size 4096) and can be fixed by updating the graph configuration.