Potentially useless allocations when checking a field cardinality
👋🏻 Hey folks
In a service running JanusGraph embedded, I observed a number of sizeable allocations coming from
JanusGraphVertexFeatures#getCardinality
(https://github.com/JanusGraph/janusgraph/blob/2c71b378339a3ab49b961eef29b5a042d018f513/janusgraph-core/src/main/java/org/janusgraph/graphdb/tinkerpop/JanusGraphFeatures.java#L161-L169).
From a profile (attached), it looks like
- A 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).
- The transaction will allocate a CaffeineVertexCache
(https://github.com/JanusGraph/janusgraph/blob/2c71b378339a3ab49b961eef29b5a042d018f513/janusgraph-core/src/main/java/org/janusgraph/graphdb/transaction/StandardJanusGraphTx.java#L335).
- The 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).
I believe the sizeable allocations come from having batch loading enabled (making the initial NonBlockingHashMap
size 4096) and can be fixed by updating the graph configuration.
That said, we could maybe disable the vertex cache by default when checking a vertex property's cardinality?
As in this change: https://github.com/JanusGraph/janusgraph/pull/4506/files
Happy to hear any feedback. Thanks!![No description](https://cdn.answeroverflow.com/1250002739195416658/Screenshot_2024-06-11_at_10.20.37.png)
1 Reply
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