Bug#682264: #682264, libapache2-mod-perl2: Crash at server startup when pre-loading Plack app

[Dominic Hargreaves]

On Fri, Sep 01, 2017 at 03:47:57PM +1000, Dmitry Smirnov wrote:
> I had the same problem until I've realised that Apache now uses event module
> by default. Solution is simple -- just switch to (traditional) MPM Prefork
> model as follows:
> 
> ~~~~
> a2dismod mpm_event
> a2enmod mpm_prefork
> ~~~~

Hi Dmitry,

Thanks for pointing this out. And to the original submitter, I'm sorry
that there was no reply on this bug before in many years!

As far as I know from a quick bit of digging it is indeed the case
that mod_perl will not work with the event mpm, so we should
arrange for it to either not be possible to load it it in that
configuration, or at least to print dire warnings if that happens
(which may be safer in any case).

I will try and have a look at this at some point but it might not be
soon, so help would be appreciated.

FTR, Red Hat does the same thing:
<https://bugzilla.redhat.com/show_bug.cgi?id=1059225>.

Kjetil, do you have any additional observations about this bug since
it was first filed in 2012? (For example did you find out that it
was in fact caused by use of the event mpm?)

<https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=682264>.

Best,
Dominic.