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https://issues.apache.org/jira/browse/SLING-10011?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17259643#comment-17259643
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Miroslav Smiljanic commented on SLING-10011:
--------------------------------------------
I have created [benchmark
test|https://github.com/apache/jackrabbit-oak/commit/5dfd1145a0b71c4a1626b1fc6430b3ec40e9c4c0]
in Oak to compare performance of Node API vs Session API in retrieving the
parent node.
Test run below utilises in-memory cache (100MB by default).
{noformat}
> java -jar target/oak-benchmarks-*-SNAPSHOT.jar benchmark
> GetParentNodeWithNodeAPI GetParentNodeWithSessionAPI Oak-Segment-Tar
Apache Jackrabbit Oak 1.37-SNAPSHOT
# GetParentNodeWithNodeAPI C min 10% 50% 90% max
N mean
Oak-Segment-Tar 1 2 2 2 3 5
25891 2
# GetParentNodeWithSessionAP C min 10% 50% 90% max
N mean
Oak-Segment-Tar 1 26 27 29 32 40
2069 29
{noformat}
Parent node retrieval operation for 90% of executions is ~10 times slower when
using Session API.
Second run is with disabled cache, to simulate high eviction rate of in-memory
cache, that can happen when sling application is under heavy load with big
number of concurrent requests.
{noformat}
> java -jar target/oak-benchmarks-*-SNAPSHOT.jar benchmark --cache 0
> GetParentNodeWithNodeAPI GetParentNodeWithSessionAPI Oak-Segment-Tar
Apache Jackrabbit Oak 1.37-SNAPSHOT
# GetParentNodeWithNodeAPI C min 10% 50% 90% max
N mean
Oak-Segment-Tar 1 7 8 9 10 14
6812 9
# GetParentNodeWithSessionAP C min 10% 50% 90% max
N mean
Oak-Segment-Tar 1 2209 2210 2227 2249 2274
27 2230
{noformat}
In this case, parent node retrieval operation for 90% of executions is ~200
times slower when using Session API.
In this test, tar segment store is used, with segments persisted on a local
SSD. When remote segment store implementation is used (Azure/AWS), test with
Session API would be even slower because of the network roundtrips involved.
> Use javax.jcr.Item.getParent() when resolving parent JCR node in
> JcrResourceProvider#getParent
> ----------------------------------------------------------------------------------------------
>
> Key: SLING-10011
> URL: https://issues.apache.org/jira/browse/SLING-10011
> Project: Sling
> Issue Type: Improvement
> Components: JCR
> Affects Versions: JCR Resource 3.0.22
> Reporter: Miroslav Smiljanic
> Priority: Minor
> Time Spent: 20m
> Remaining Estimate: 0h
>
> Currently
> [JcrResourceProvider.getParent|https://github.com/apache/sling-org-apache-sling-jcr-resource/blob/org.apache.sling.jcr.resource-3.0.22/src/main/java/org/apache/sling/jcr/resource/internal/helper/jcr/JcrResourceProvider.java#L361]
> is using JcrItemResourceFactory.getItemOrNull(String path), which eventually
> is using JCR session to retrieve parent node using absolute path.
> I propose using javax.jcr.Item.getParent() instead.
> Reasoning wold be to utilise potential improvements in JCR implementation
> that would for a given node retrieve the whole subtree. That can be
> configured for example by using particular node type or node path.
> {noformat}
> root
> |
> a
> / \
> b c
> {noformat}
> If node 'a' in picture above, is matching desired configuration, then code
> below would return the whole subtree.
> {code:java}
> Node a = jcrSession.getNode("a");
> {code}
> That further means retrieved subtree can be traversed in memory, without the
> need to communicate with the JCR repository storage.
> (!)That is particularly important when remote (cloud) storage is used for
> repository in JCR implementation, and tree traversal can be done without
> doing additional network roundtrips.
> {code:java}
> //JCR tree traversal happens in memory
> Node b = a.getNode("b");
> Node c = a.getNode("c");
> {code}
> Also going from child to parent, is resolved in memory as well (proposal
> relates to this fact)
> {code:java}
> //JCR tree traversal happens in memory
> assert b.getParent() == c.getParent();
> {code}
> Jackrabbit Oak, for document node store is supporting node bundling for
> configured node type
> [http://jackrabbit.apache.org/oak/docs/nodestore/document/node-bundling.html]
> Currently I am also doing some experiments to support node
> bundling/aggregation for arbitrary node store
> ([NodeDelegateFullyLoaded|https://github.com/smiroslav/jackrabbit-oak/blob/ppnextgen_newstore/oak-jcr/src/main/java/org/apache/jackrabbit/oak/jcr/delegate/NodeDelegateFullyLoaded.java],
>
> [FullyLoadedTree|https://github.com/smiroslav/jackrabbit-oak/blob/ppnextgen_newstore/oak-core/src/main/java/org/apache/jackrabbit/oak/core/FullyLoadedTree.java]).
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