Issue Apache2+PHP5-FPM

[denede]

From time to time the site will get very very slow to load, from 350ms to almost 10seconds and in the logs will see something like:

[Fri Sep 29 13:29:11.019399 2017] [proxy_fcgi:error] [pid 8307:tid 140556948657920] (104)Connection reset by peer: [client 70.69.151.65:53397] AH01075: Error dispatching request to :

or something like:

[Fri Sep 29 12:21:26.718503 2017] [proxy:error] [pid 12923:tid 139989809043200] (2)No such file or directory: AH02454: FCGI: attempt to connect to Unix domain socket /var/www/vhosts/system/domain.tld/php-fpm.sock (*) failed
[Fri Sep 29 12:21:26.718511 2017] [proxy_fcgi:error] [pid 12923:tid 139989809043200] [client 185.45.195.190:48534] AH01079: failed to make connection to backend: httpd-UDS

I am using Apache2 with PHP5-FPM handler. I checked various articles including:
Website shows 503 Service Unavailable if PHP-FPM support is enabled: AH01079: failed to make connection to backend
Website is not accessible, when domain name contains uppercase letters: Service Temporarily Unavailable

I dont use upercase letters and the php-fpm.sock file is indeed into the proper location
Like i said from time to time this will happen and the site will get very annoying slow.
I saw some topics around here but non helped
I am using Debian8 Jessie with latest Plesk Onyx Version (
Plesk Onyx
Version 17.5.3 Update #23, last updated on Sept 28, 2017 03:51 PM)

 

[Bitpalast]

This can have two major reasons
a) The PHP script runs very long or does not deliver an output before a timeout is up.
b) The PHP FPM children are exhausted, a new child cannot be created.

Please try to increase the max_children value greatly as described in How to change PHP-FPM pool settings for a domain in Plesk .