On Tue, 2009-11-03 at 10:27 +0100, André Warnier wrote:

>  Greetings from sunny (right now anyway) Southern Germany.

Greetings from the cloudy Netherlands... BTW my colleagues from Straubing (Bavaria, Germany)
 were complaining that it's raining cats and dogs today there.

>  I see that you mention mysql.  This probably means DBI.
>  I think you need to be a bit careful with DBI and Apache::Reload.  I 
>  seem to recall that there are some particularities there
>  (Probably in relation to permanent cached database connections).

The project I work on uses mod_perl, Apache::Reload, and Apache::DBI.
AFAIK Apache::Reload does not influence the database connection at all,
it just would monitor the modules on disk and if they change, they are
reloaded in memory. We use Apache::DBI to cache the database connection,
which basically means that the Apache child does not need to set up a
new connection any time it tries to open one. This has a performance
benefit.

>  In any case, I believe Apache::Reload is OK for a development server, 
>  but on a production server this is probably not very efficient.
>  There is no free lunch : if you ask the server to monitor certain things 
>  and do something in case of change, then that has a cost.

We use it (and even recommend it) on a production server! We have
measured a performance degradation of about 7% when running with
Apache::Reload. In most setups, this would not be an issue and it is
better than having to restart apache.... but of course in a high-load
environment it will be something to consider.
--
Michiel