[DBD-SQLite] DBI, DBD::SQLite and threads

[Martin J. Evans]

On 19/03/12 04:19, Adam Kennedy wrote:
> I've noticed there's a lot of movement at the moment on DBI, threading
> and performance.
>
> http://www.martin-evans.me.uk/node/131

The issue here was that when using a threaded Perl the state structure had to be protected and there was a slow and a faster way of accessing it. Some DBDs were using the slow method.

> In Padre we've always stuck to the use of DBI only in the parent
> thread, but the time is fast approaching where it would be very handy
> to run multiple database connections for things like background
> indexing of code and the like.

When you build DBI it still says:

*** You are using a perl configured with threading enabled.
*** You should be aware that using multiple threads is
*** not recommended for production environments.

but I'm unsure to what degree this still applies.

Some DBDs are still littered with dTHR macros which as far as I am aware has been a noop since Perl 5.8.
  
> I was wondering if anyone has any experiences with DBD::SQLite and
> threads, or can speak with some authority on where we are with regards
> to them (I do know that the CLONE method seems to blank out the driver
> structure forcing it to load again in the new thread).
>
> Regardless of whether they currently work or not, I'd like to be able
> to write a =head2 section in the POD documentation stating our current
> position on threads and recommendations before the next release.
>
> If they can be used in threads, it would be nice to be able to write a
> DBD::SQLite::Cookbook entry on using threads.
>
> I'm happy to do the POD writing myself if someone wants to just reply
> with information to the mailing list.
>
> Thanks all
>
> Adam K

I'm afraid I neither use a Perl with threads enabled or threads - which is a shame as I didn't see any benefit from that huge change to DBD::Oracle.

I note DBD::SQLite does not seem to be using the DBIS macro so there is nothing to change.

Sorry that does not necessarily help you with SQLite and using threads.

Martin
-- 
Martin J. Evans
Easysoft Limited
http://www.easysoft.com