Re: DBD::Pg, DBD::Oracle and others are slow with threads due to DBIS

On Tue, 13 Mar 2012 21:44:06 +0000, Tim Bunce <[email protected]>
wrote:

> On Fri, Mar 02, 2012 at 03:11:17PM +0000, Tim Bunce wrote:
> > > 
> > > The second patch, which makes DBIS more efficient, is a lot more complex,
> > > and more likely to break things (especially as it's changing a bunch of
> > > macros that are directly #included by the DBD drivers. You may need to
> > > bump API version numbers; I don't understand that bit.
> > 
> > I'm concerned that changing the API, and thus forcing all compiled
> > drivers to be recompiled at the same time the DBI is installed,
> > isn't worth the gain. Especially as drivers shouldn't be using DBIS in
> > any hot code anyway.
> 
> I finally got around to looking at DBD::Pg and was horrified to discover
> the number of DBIS calls made by hot paths in the code. Most are hidden
> behind various tracing macros. Even fetch calls 3 + 3 * num_of_fields!

When hidden, it won't stand out to the maintainers.

How do we/I see where it happens? Do you have a (short) guide to check
if my/a DBD (CSV, Unify, File) uses those too?

> Then I looked at DBD::Oracle and discovered the same kind of thing.
> Which is particularly disappointing for me as I wrote the tracing
> mechanism it uses (though maybe that pre-dated thread support).
> 
> Anyway, the upshot is that getting DBIS calls out of major drivers will
> require a fair bit of work. It's just grunt-work really, nothing complicated.
> As you noted with DBD::mysql, Dave, the performance gains are worth it.
> 
> Any volunteers? Naturally I'll be happy to suggest an approach I think
> will work well (basically an extension of that used by DBD::Oracle).
> 
> Dave, I'll get back to you about the DBIS changes soon, I hope.

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