Can't locate loadable object for module main in @INC

Question

In a mod_perl application running on ubuntu 16.04 after a certain while where everything functions fine (a few days) we get a fatal message in the errorlog:

failed to resolve handler MyHandler::ModPerl20 Can't locate loadable object for module main in @INC

MyHander::ModPerl20 is defined in a location block

<Perl>
     unshift @INC, '/path/to/my/code';
</Perl>
<Location ~ "/imp($|/)">
    SetHandler modperl
    PerlResponseHandler MyHandler::ModPerl20
</Location>

The ubuntu Perl Version is 5.22. Apache 2.4

Can this be the problem? http://blog.feature-addons.de/2016-05-15-otrs-apache-mod-perl-perl-5-22

Any ideas how to fix this? Do I really have to set up nginx/uwsgi?

Extraordinary

It means the binary component of the module (the .so) can't be found. How did you install MyHandler::ModPerl20? – Expositor

MyHandler::ModPerl20 is a pure Perl Handler written by me. It does not have any .so File. It does work @ the same installation without any problem for a few days. – Extraordinary

What is the loadable Object 'main' for a PerResponseHandler in mod_perl? – Extraordinary

After restarting apache. Does this error appear again? – Stratocracy

After restarting apache, everything is fine (This is currently the workaround we use, to restart the apache once every 24h per cron-job). But i was afraid I have made a "mistake" buried deep inside and want to know, where i have to look for errors made by me. – Extraordinary

Answer 1

Changing the MPM Apache configuration from mpm_event to mpm_prefork solved my problem.

It does not explain the error message though :( Any hints on this are appreciated.

Extraordinary

Just had this exact same problem when upgrading Perl. It must be some kind of race condition in my module and/or mod_perl. Thanks for the tip! – Shreve

Answer 2

Make sure @INC is set up correctly, in order to find the path in which MyHandler::ModPerl20 is installed (I think what happens is that when Apache recycles some child, the one starting fresh do not have the correct @INC value, hence not finding your module anymore).

Try to add a PerlSwitches -I/your/path/for/myhandler/ in httpd.conf to see if it fixes your problem.

If that changes things, have a look at Adjusting @INC in modperl documentation to see all details.

Tulley

@INC is set up correctly (I updated the question with the code used). Anyway how could it be functioning correctly for a few hundreds requests, and then crash with the message given? And why is the Apache/mod_perl looking for module main in my Handler? – Extraordinary

Because from vague memory I had a similar problem that was solved by changing how to set up @INC. The result can change depending on how Apache/its child are being started. You loose nothing by trying the PerlSwitches statement suggested and even putting your MyHandler::ModPerl20 perl module in one of the path hardcoded in perl default @INC on your site to see if it makes your problem disappear. – Tulley

I cannot imagine that this is the problem, sorry :( IF the @INC gets wrong, I would get an error-message like: failed to resolve handler 'MyHandler::ModPerl20': Can't locate MyHandler/ModPerl20.pm in @INC and not Can't locate loadable object – Extraordinary

Answer 3

I have seen something similar other times, not only with SAS, but with other products as well.

I would ask your system admin to check the IO modules in your Linux server. I think they need re-installation, or maybe just check the authorizations on the relative folders.

Rendarender

How can one check IO-Modules? What exactly does this mean? – Extraordinary