[jira] [Created] (OAK-839) Optimization in the Node#getNodes

["Antonio Sanso (JIRA)" <ji...@apache.org>]

Antonio Sanso created OAK-839:
---------------------------------

             Summary: Optimization in the Node#getNodes
                 Key: OAK-839
                 URL: https://issues.apache.org/jira/browse/OAK-839
             Project: Jackrabbit Oak
          Issue Type: Improvement
          Components: jcr
            Reporter: Antonio Sanso


I have done some simple test with Node#getNodes and it seems that is really slow (specially compared with the Jackrabbit case).

My test is really simple. (see as well attached GetNodesTest).

I create a node with 10000 children and do 

NodeIterator iterator = reader.getNode("/a").getNodes();

The performance test shows a huge regression if compared with Jackrabbit

* Jackrabbit

Apache Jackrabbit Oak 0.9-SNAPSHOT
# ReadStatusTestSingleACL        min     10%     50%     90%     max       N
Jackrabbit                         0       0       0       1      10   33592


* Oak

Apache Jackrabbit Oak 0.9-SNAPSHOT
# ReadStatusTestSingleACL        min     10%     50%     90%     max       N
Oak-Memory                       123     125     128     144     168     115

Me and [~tmueller] were able to find the cause of the sloweness.
It seems that the o.a.j.oak.jcr.delegate.NodeDelegate and o.a.j.oak.jcr.NodeImpl are calling getChildrenCount that seems to be an expensive operation (and not really needed in this case).

Patch to follow


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