Fairly high load on web server, very slow to load some pages

[sudo]

Personally I would move to Nginx but it can be a bit to get your head around and apache is better than it used to be for load.

[AtariAge]

Just now, sudo said:

Personally I would move to Nginx but it can be a bit to get your head around and apache is better than it used to be for load.

That would be interesting to explore after everything else.  I know many people here are running it, and I saw a thread where someone put together a tutorial on how to move from Apache to Nginx.  I'm running WHM/cPanel, so I imagine that might be a bit of a pain from that standpoint.  Plus this is a fully-managed server, and they likely wouldn't support the Nginx installation should there be issues. 

Okay, I just took a look and it seems cPanel is adding Nginx support.  It's already available in an experimental build, but I'm not brave enough to try that on the production server.  I have other servers I can test it on, though.  No timeline on when they might add it to production, but this is promising:

https://blog.cpanel.com/brace-yourselves-nginx-is-coming/

I'll need to read more about Nginx, I'm not terribly familiar with it yet.

 ..Al

[AtariAge]

Looks like I'm having a problem with PHP-FPM.  Sometimes Apache stops responding to requests, and I don't see any more php-fpm processes running.  I had to switch back to php-cgi to get the site back online.  I looked through the Apache error log and found quite a few lines like these:

[Wed Jul 03 22:20:16.028372 2019] [proxy_fcgi:error] [pid 12645] (104)Connection reset by peer: [client 110.249.201.217:10762] AH01075: Error dispat
ching request to : 
[Wed Jul 03 22:20:16.028452 2019] [proxy_fcgi:error] [pid 12652] [client 111.225.148.7:11198] AH01067: Failed to read FastCGI header
[Wed Jul 03 22:20:16.028491 2019] [proxy_fcgi:error] [pid 12652] (104)Connection reset by peer: [client 111.225.148.7:11198] AH01075: Error dispatch
ing request to : 
[Wed Jul 03 22:20:16.028512 2019] [proxy_fcgi:error] [pid 12651] [client 125.209.235.178:37891] AH01067: Failed to read FastCGI header
[Wed Jul 03 22:20:16.028586 2019] [proxy_fcgi:error] [pid 12651] (104)Connection reset by peer: [client 125.209.235.178:37891] AH01075: Error dispat
ching request to : 
[Wed Jul 03 22:20:16.028620 2019] [proxy_fcgi:error] [pid 12150] [client 110.249.202.82:63448] AH01067: Failed to read FastCGI header
[Wed Jul 03 22:20:16.028642 2019] [proxy_fcgi:error] [pid 12527] [client 54.36.148.120:38628] AH01067: Failed to read FastCGI header

When I first setup PHP-FPM, I had to increase MaxClients to 2500 and MaxRequestWorkers to 2000, or Apache would crash after a few minutes.  I also changed the PHP-FPM Pool options as follows:

This seemed more stable, but twice today I've had the site become completely unresponsive.  And restarting Apache doesn't seem to help, not until I switched back to PHP-CGI.  This is a bit frustrating, as PHP-FPM seems to use less resources, but is unstable for some reason.  I haven't had any issues with PHP-CGI.  I'm not sure the best way to troubleshoot this. 

 ..Al