CODEWITHSUNDEEP
neo4j
user3845217
user3845217

Reputation: 23

Memory leak behavior in Neo4j community edition

I previously posted on the neo4j mailing list (https://groups.google.com/forum/#!topic/neo4j/zn-7lKHVvNI) but haven't received any response from the community, so I'm x-posting here...

I've noticed what appears to be memory leak behavior from neo4j community edition. Running this test code (https://gist.github.com/mlaldrid/85a03fc022170561b807) against 2.1.2 (also tested against 2.0.3) and a 512MB heap results in GC churn after a few hundred thousand cypher queries. Eventually I either get an OutOfMemory error or jetty times out.

However, when I run the same test code against an eval copy of the neo4j enterprise edition it proceeds though 3.5M queries with no signs of bumping up against the 512MB heap limit. I killed the test after that, satisfied that the behavior was sufficiently different from the community edition.

My questions are thus: Why is this memory leak behavior different in the community and enterprise editions? Is it something that the enterprise edition's "advanced caching" feature solves? Is it a known but opaque limitation of the community edition?

Thanks for any insight on this issue.

Upvotes: 2

Views: 1161

Answers (2)

Pavel Niedoba
Pavel Niedoba

Reputation: 1557

I'm posting output of Sampler of jvisualvm Sampler of jvisualvm

I guess this answer the question as the leak is still there in 2.2.0

Edit:

The problem was using ExecutionEngine. I used execute method on GraphDatabaseService instead and it solved my problem

Upvotes: 0

Jacob Davis-Hansson
Jacob Davis-Hansson

Reputation: 2663

This is a recently discovered memory leak in 2 of the 4 cache types available for the community edition (weak and soft caches). It does not affect enterprise as enterprise uses the 'hpc' cache per default.

It only affects deployments where you are unlikely to read from the existing data in the db, or where the majority of load on the system is writes.

We've got a fix for this which will go out in subsequent releases. For now, if your use case is unfortunate enough to trigger this issue, you'll need to use either the 'strong' cache or 'none' in community, or switch to enterprise until the next patch release.

Upvotes: 3

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