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https://issues.apache.org/jira/browse/JCR-3588?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13649644#comment-13649644
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Jukka Zitting commented on JCR-3588:
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The CPU use on the node with no user load is due to the indexer catching up
with changes happening on the other node. For performance reasons the
Jackrabbit 2.x clustering architecture keeps a search index locally on each
cluster node (and there's no easy way to share index updates across nodes),
which is why the indexing work needs to be duplicated on each cluster node.
>From the information included here it's hard to tell why you'd experience the
>behavior you're seeing. Can you reduce the issue to a simple test case that
>can be reproduced elsewhere?
> Response time higher on Node1 with load when Node2 has no load
> --------------------------------------------------------------
>
> Key: JCR-3588
> URL: https://issues.apache.org/jira/browse/JCR-3588
> Project: Jackrabbit Content Repository
> Issue Type: Bug
> Components: clustering
> Affects Versions: 2.4.3
> Environment: CentOS 6.4 running WebSphere Application Server
> 7.0.0.19. Jackrabbit cluster configuration with 2 WAS servers. Repository on
> DB2 9.7.
> Reporter: Cody Burleson
> Attachments: JackrabbitCluster-ResponseTime.png, Node1repository.xml,
> Node2repository.xml, Screen Shot 2013-05-03 at 3.49.52 PM.png, Screen Shot
> 2013-05-03 at 4.04.32 PM.png, Screen Shot 2013-05-03 at 4.14.52 PM.png
>
>
> In our performance analysis, we are seeing a strange effect, which we does
> not make sense to us. It may or may not be a defect, but we need to
> understand why the effect occurs. In a 2 node cluster, we can run a certain
> load (reading and writing) directly on Node1 and an equivalent load (reading
> and writing on Node2). We measure the response time on both nodes, and it's
> less than 2 seconds. If we stop the load to one of the servers, the response
> time on the other server triples (with no additional load). See attached
> image "JackrabbitCluster-ResponseTime.png". The left side of the report shows
> when only one node (Node1) has load and Node2 has no load. In this case, the
> response times on Node1 are at about 6 seconds. Then, on the right side of
> the report, we add an equivalent load to Node2 and then the response times on
> Node1 drop to 2 seconds. So, the load on Node1 was always consistent, yet
> ADDING load to Node2 actually improves response time on Node1. Logically, it
> doesn't make much sense, eh? Someone, please, at least help us understand why
> this may be happening.
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