What causes child died with signal 7?

Question

PHP

Good afternoon everyone.
There is one VDS with Debian and apache2. It hosts several sites. One of the sites is the main, but at the same time the most problematic: the fact is that it constantly has a 324 error. In an attempt to find the source of its occurrence, I got into /var/log/apache2/error.log and saw the following:

...
[Thu Dec 13 10:51:12.341046 2018] [mpm_itk:error] [pid 5922] child died with signal 7
[Thu Dec 13 10:51:12.400208 2018] [mpm_itk:error] [pid 5923] child died with signal 7
[Thu Dec 13 10:51:12.568292 2018] [mpm_itk:error] [pid 5921] child died with signal 7
[Thu Dec 13 10:51:12.813087 2018] [mpm_itk:error] [pid 5916] child died with signal 7
[Thu Dec 13 10:51:13.048035 2018] [mpm_itk:error] [pid 5917] child died with signal 7
[Thu Dec 13 10:52:52.048885 2018] [mpm_itk:error] [pid 5981] child died with signal 7
[Thu Dec 13 10:56:09.816322 2018] [mpm_itk:error] [pid 6844] child died with signal 7
[Thu Dec 13 10:57:05.965735 2018] [mpm_itk:error] [pid 6988] child died with signal 7
[Thu Dec 13 10:59:13.439414 2018] [mpm_itk:error] [pid 7282] child died with signal 7
...

I don't know if this error is related to the 324 response from the server, but I would like to know more about it.
Google, unfortunately, did not help me much; all I could dig up was that the problem had something to do with memory. The memory on the VDS is 12 GB, of which 11 is free. I wrote to the hoster, but he did not help from the word at all.
So the question is, what could be causing this error?
UPD 12/21/2018
Unfortunately, disabling opcache did not help.

Answer 1

• mpm_itk is an Apache module for multiprocessing virtual hosts;
  Based on a combination of symptoms, the process serving the site is crashing due to a hardware or internal error. It is worth, firstly, updating Apache to the latest version, and secondly, viewing the system logs. Depending on the contents of the system logs, you will either need to contact the hosting TP or create a bug report to the Apache developers.

Answer 2

Error 324 is an empty response from the server, probably? Yes, then it's connected.
Signal 7 is SIGBUS, most often these are problems with memory access. It can be caused by both hardware problems and software errors. Well, it doesn't matter how much of that memory is - it's not a problem with its volume - it's a problem that something is accessing the wrong addresses.
To fight, it is worth trying to update the server software for a start.
If the problem persists, try disabling opcache, and if it helps, play around with its settings.
If the problem is not solved, localize at what requests it occurs and see what extensions or external programs are called (usually this happens in such scenarios). Also, you can install software with debug symbols, enable dumping and analyze them to get additional information.

Answer 3

Are you sure that Apache does not eat these free 11 gigs for you?
Show the full apache config, along with itk. His default settings are very evil.

Answer 4

Probably the memory has a bad sector or sectors. Memtest required.
You can still do it on your own hardware, but how to convince the hoster to check it ...

Answer 5

Hello. Tell me how did you solve this problem? Because I have the same and I can not solve it in any way.