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From "Knut Anders Hatlen (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (DERBY-5068) Investigate increased CPU usage on client after introduction of UTF-8 CcsidManager
Date Thu, 28 Apr 2011 13:06:03 GMT

     [ https://issues.apache.org/jira/browse/DERBY-5068?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel

Knut Anders Hatlen updated DERBY-5068:

    Attachment: d5068-1a.diff

The attached patch makes the two methods encode the strings without going via an intermediate
object. I haven't double checked that the encoding is correct, but it should be sufficient
for testing purposes.

I ran the sr_select test with 10 threads using derbyclient.jar from, and
patched trunk. Four runs with each configuration gave the following average CPU time spent
per transaction: 76.4 µs 81.3 µs
trunk+patch: 76.8 µs

So it looks like that approach will bring the CPU usage back down to the 10.6 level.

> Investigate increased CPU usage on client after introduction of UTF-8 CcsidManager
> ----------------------------------------------------------------------------------
>                 Key: DERBY-5068
>                 URL: https://issues.apache.org/jira/browse/DERBY-5068
>             Project: Derby
>          Issue Type: Task
>    Affects Versions:
>            Reporter: Knut Anders Hatlen
>         Attachments: d5068-1a.diff
> While looking at the performance graphs for the single-record select test during the
last year - http://home.online.no/~olmsan/derby/perf/select_1y.html - I noticed that there
was a significant increase (10-20%) in CPU usage per transaction on the client early in October
2010. To be precise, the increase seems to have happened between revision 1004381 and revision
1004794. In that period, there were three commits: two related to DERBY-4757, and one related
to DERBY-4825 (tests only).
> We should try to find out what's causing the increased CPU usage and see if there's some
way to reduce it.

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