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From Chris Anderson <>
Subject Re: Query server perfromance issues ..
Date Sat, 19 Sep 2009 16:57:08 GMT
On Sat, Sep 19, 2009 at 5:13 AM, Debasish Ghosh
<> wrote:
> Hi -
> As I have mentioned previously I have been working on a Scala driver for
> CouchDB, which also includes a Query Server. I was working with an April
> snapshot of 2009/04/23. This worked fine for all the views and validations
> that I have written.Things were running fine and I could write map/reduce
> and validation functions in Scala.
> Recently I tried to upgrade to trunk. Suddenly the views and validations
> became very very slow. After some fact finding, I tried to poke into *
> couch_query_servers.erl*, since that seemed to be the obvious area to look
> into. I may be worng though, but it was a blind guess.
> I noticed that previously I was working with *revision 749852* of the file,
> which delivered the goods for me. Then when I faced problems with the trunk,
> I started doing a git reset to earlier versions of this file. Now I find
> that it looks like the performance problem starts from *revision 780165* of
> this file. Have a look at
> the difference. Looks like there have been some major changes. I am
> just
> wondering if this change has anything to do with the performance issue.

A quick scan of that diff suggests that the only real behavior change
that should effect you is the ["reset"] call for recycled processes.
Maybe reset is expensive in your implementation?

BTW, have you tried running:

spec test/query_server_spec.rb -f specdoc --color

It should be simple to extend that test suite to test your scala
server. If there are patches we can make to make it easier to
integrate outside projects with the query server test suite, I'm happy
to help there as well.

> Any help, pointer will be appreciated.
> Thanks.
> - Debasish

Chris Anderson

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