Problem with php curl module, how to fix?

Question

PHP

Periodically, wordpress scripts terminate with a 502 server error
. From the apache logs, I observe:

apache2: res_query.c:262: __libc_res_nquery: Assertion `(hp != ((void *)0)) && (hp2 != ((void *)0))' failed.
[Thu Mar 17 21:17:48.674309 2016] [mpm_itk:error] [pid 9577] child died with signal 6

The server is running Debian 8 ISPmanager 5.5 (software has been updated).
The problem occurs with Apache MPM-ITK, fast-cgi modes.
php5-curl: Installed: 5.6.17+dfsg-0+deb8u1
Hosting support replied that there is not enough RAM citing an outdated entry from the kernel log (Out of memory: Kill process 16954 (apache2)). It seems to me that this is not the point.
Tried on another Debian 8 ISPmanager 5.5 zero build server - same thing.
Also tried different versions of wordpress.
Please help me solve the problem

Answer 1

the first step was to see how much memory is available for php on that server.
if there is no information, then for example

<?php 
echo  ini_get('memory_limit');

Answer 2

I have the same problem. Curl handles existing addresses correctly. The failure occurs when a non-existent page is requested. In theory, if the page does not exist, curl_errno() and curl_error() let you know about it, but in my case this does not happen. Everything ends with a page break, and similar entries appear in the apache logs:
apache2: res_query.c:262: __libc_res_nquery: Assertion `(hp != ((void *)0)) && (hp2 != ((void *)0)) ' failed.
[Sun Apr 03 10:53:30.420827 2016] [mpm_itk:error] [pid 512] child died with signal 6
Server runs on Debian GNU/Linux 8.4 (jessie)
ISPmanager 5 Lite
php5-curl: 5.6.19+dfsg-0 +deb8u1 Could
n't find any normal information on fixing this error either.