Cody Burleson created JCR-3588:
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Summary: 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
Fix For: 2.4.3
Attachments: JackrabbitCluster-ResponseTime.png, Node1repository.xml,
Node2repository.xml
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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