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https://issues.apache.org/jira/browse/QPID-3644?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14149227#comment-14149227
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Justin Ross commented on QPID-3644:
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[~kpvdr], this one's pretty old. Can we close it?
> qpid-perftest on c++ broker shows large consume rate drops at 64k message
> size boundaries
> -----------------------------------------------------------------------------------------
>
> Key: QPID-3644
> URL: https://issues.apache.org/jira/browse/QPID-3644
> Project: Qpid
> Issue Type: Bug
> Components: C++ Broker, C++ Client
> Affects Versions: 0.15
> Reporter: Kim van der Riet
>
> Using a 2-machine test connected with 10g private network, with one machine
> containing the broker and the other the client, the following was observed:
> Broker machine (20.0.10.43 on the 10g network):
> ./qpidd --auth no
> Client machine:
> ./qpid-perftest -b 20.0.10.43 --count 20000 --size 65400
> (result: consume rate: 5437.45 transfers/sec)
> ./qpid-perftest -b 20.0.10.43 --count 20000 --size 65500
> (result: consume rate: 696.628 transfers/sec)
> which is a massive drop (to 13% of the initial rate) for a relatively small
> change in message size of 100 bytes.
> Again, around the 128k boundary:
> ./qpid-perftest -b 20.0.10.43 --count 20000 --size 130900
> (result: consume rate: 546.144 transfers/sec)
> ./qpid-perftest -b 20.0.10.43 --count 20000 --size 131100
> (result: consume rate: 177.607 transfers/sec)
> which compounds the previous consume rate drop.
> Further observations:
> 1. If qpid-perftest is modified to print a single char every 100 consumes,
> then it can be observed that performance is not linear, but starts out fast,
> but slows down as the test progresses. Near the end of the test, the consume
> rate starts to rapidly pick up again.
> 2. Looking at broker trace logs, the consumed messages have a 40-byte header.
> This means for these tests that the total message sizes are:
> 65400 + 40 = 65440
> 65500 + 40 = 65540
> 130900 + 40 = 130940
> 131100 + 40 = 131140
> which straddle the 64k and 128k size boundaries.
> 3. The drop in performance is not a step function, but as one draws closer to
> (but still below) the boundary, the rate starts to rapidly deteriorate. eg
> 65450 + 40 is below the 64k boundary, and has a result between the 65400 and
> 65500 rates. Similarly for 131000 + 40, which is slightly below the 128k
> boundary.
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