Bug#625223: Please make the different MPMs co-installable

[Stefan Fritsch <sf@sfritsch.de>]

On Monday 02 May 2011, Christoph Berg wrote:
> | MPMs
> | ====
> | 
> | You can use different MPMs for different instances by setting
> | APACHE_HTTPD to one of /usr/lib/apache2/mpm-*/apache2. Note that
> | some modules like mod_php only work with the non-threaded MPMs
> | (prefork, itk).
> 
> Along with the magic in /etc/init.d/apache2, /usr/sbin/apache2ctl
> and the other scripts that recognize -$favour suffixes, this works
> like a charm to run multiple instances in parallel.
> 
> Unfortunately, the Debian packaging prevents the co-installation of
> multiple Provides/Conflicts: apache2-mpm fields. The only file that
> is actually conflicting is /usr/sbin/apache2 - this could easily
> be taken care of by making it an "alternative". It is already a
> symlink, it would just be managed by update-alternatives instead
> of being shipped in some package. (Maybe with a raised priority
> for the "default" MPM.)
> 
> I would be willing to write a patch for this if the maintainers
> don't think there would be an objection to enabling multiple
> instances with different MPMs.

I am not sure what problem you want to solve, exactly. AFAIK, there is 
no package that exclusively depends on a threaded MPM. Therefore, you 
can simply install apache2-mpm-prefork and have no dependency 
problems. For each instance, you can still use whatever MPM you want 
via the APACHE_HTTPD variable in the /etc/apache-xxx/envvars file. Am 
I missing something? Or should the documentation be clearer?

In any case, Apache httpd 2.4 will have MPMs as dynamic modules, which 
will likely result in the apache2-mpm-* packages going away 
completely. Therefore, I don't want to spend any effort on those 
packages.