From: ahoward <ahoward@...>
Date: 2003-01-24T09:05:42+09:00
Subject: Re: mod_ruby: what's persistent and what's shared?

On Fri, 24 Jan 2003, Bill Kelly wrote:

> Hi,
>
> From: "Ollivier Robert" <roberto@REMOVETHIS.eu.org>
> >
> > Imagine you do something like this in your httpd.conf
> >
> > -=-=-
> > RubyRequire common-data
> > -=-=-
> >
> > and that in common-data.rb you have this:
> >
> > -=-=-
> > require 'dbi'
> >
> > $DB = DBI.connect("dbi:mysql:foodb", "user", "password")
> > -=-=-
> >
> > Will all instances of httpd share the same $DB ? Remember that it is not
> > data created by a script or a .rhtml page, it is data created when you
> > start the httpd server...
>
> My guess is that this would be problematic.  Forked children
> do inherit copies of the parent's file handles (I'm assuming
> a DB connection is at its heart a file handle / socket?)
>
> My guess as to what would happen would be that the child http
> processes would indeed probably "share the same $DB", assuming
> the http.conf processing happens before the children are forked.
>
> However, I think it would likely be a problem to have the
> child processes all chattering simultaneously at the DB over
> the same connection.  I wouldn't expect that to work properly.
> (But I don't know how it's implemented, so I could be wrong.)

that approach also makes me queasy... why not simple make a little drb
conection pool?  that'd be pretty trival to implement and neatly solves the
problem externally to the web server and individual cgi scripts?

i've actually be working on a CGI::Cache for such purposes... it would be just
like a session but able so contain 'live' objects, like database handles.

-a

-- 

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 | Ara Howard
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