ERR_EMPTY_RESPONSE; "service httpd reload" solves it.. why?

Hi all,

I have a (99% working) domain running software called "ownCloud". It is working fine most of the time, but every once i a while i get an ERR_EMPTY_RESPONSE. This happens ONLY on this (SSL) domain and a "service httpd reload" solves the issue (for about a day). The logs don't show anything when this happens.

I am running
- Apache 2.4.16
- PHP 5.6.11
- with the ionCube PHP Loader (enabled) + Intrusion Protection from ioncube24.com (unconfigured) v5.0.12, Copyright (c) 2002-2015, by ionCube Ltd.
- with Zend OPcache v7.0.6-dev, Copyright (c) 1999-2015, by Zend Technologies
- with APCu extension

OpCache is built/installed using directadmin.

What i've tried:
- Switched from Apache mpm prefork to mpm event -- using the following commands:

Then i tried switching from apache_mpm=auto to apache_mpm=event

Then:

Followed by:

But that fails, since custombuild is doing:

It seems i can ONLY use prefork?

I even tried combinations of
- Enabling/disabling APCu
- Adjusted MySQL configuration to be less memory intensive

So my question is, where do i need to start looking? I had some difficulties with the migration from Apache 2.2 to 2.4 but those are all solved. I have rebuild apache/php/opcache multiple times with custombuild clean command. What do you need to know from me in order to be able to help me?

The problem is that i have to wait about a day for the problem to occur...

Right now i am running a test to see if disabling OPcache works...

Check:
/var/log/httpd/error_log

for more clues.. and perhaps that domain's log too:
/var/log/httpd/domains/domain.com.log
/var/log/httpd/domains/domain.com​.error.log

If only 1 domain is affected, is the domain on it's own IP?
I'm not sure if APC+OpChache might be fighting... but memory usage or addon modules would be my first guess to check.
Hopefully the logs provide some more info.

Running php-fpm instead of mod_php might be another option, as it runs php in it's own php server, so php modules wouldn't affect Apache itself.

John

Hi John,

Yes that domain had its own IP; after disabling OpCache the problem is still away for now.. I keep it monitored.