On server, I run Apache via FastCGI using PHP 7.4.13:
/etc/httpd/conf.d/ is configured as this:
# Use FastCGI to process .fcg .fcgi & .fpl scripts
AddHandler fcgid-script fcg fcgi fpl
# Sane place to put sockets and shared memory file
FcgidIPCDir /run/mod_fcgid
FcgidProcessTableFile /run/mod_fcgid/fcgid_shm
FcgidMaxRequestLen 33554432
FcgidIOTimeout 3600
FcgidBusyTimeout 3600
FcgidConnectTimeout 300
FcgidMaxRequestsPerProcess 500
FcgidMaxProcesses 10000
FcgidMaxProcessesPerClass 5000
However, approximatelly every 6 hours, the server "crashes" (FTP is working, static content from subdomain is working, SSH is working) and error log is full of
mod_fcgid: can't apply process slot for /var/www/php-bin/domain/php
The server resources are free during this: htop Tasks is around 600,
I have 190GB RAM (60GB is taken) and 40 cores (all under 5% according to htop), so there is plenty of power but server is not responding and returns 500-family error. After reset all is back to normal.
There seems to be no "weird" activity according to Apache access log. I currently run rsync (copying milions of small files) in low priority mode to backup my disc and this problem starts masivelly recently, when I started rsync. I am not sure if it is related problem or not, but I cannot quit rsync.
