I have a 4 cpu core VPS with 4GB ram. It is running Ubuntu 10.04 with nginx/0.7.65, PHP 5.3.2, and MySQL. I use php5-fpm for the communication to nginx. I also have php5-apc complimenting with php caching.
This system runs four sites and shows approximately 2.5 million page views per day.
Introduction to problem - The sites will intermittently show error 404 when loading a page. It potentially happens on every page, and I can sit there and refresh over and over and it will happen on average once in every seven to ten times.
What I've tried - Updating Ubuntu and nginx, playing with php and nginx configurations. this problem has been replicated on Ubuntu 11.10 and nginx/1.0.5.
Notable logs - Nginx error.log and access.log show nothing out of the ordinary, but do report when a 404 is issued. php5-fpm.log displays:
Nov 20 21:47:45.640003 [ERROR] [pool www] unable to retrieve process activity of one or more child(ren). Will try again later.
but I am not convinced that is related to this issue, as i've seen it in previous setups.
Configurations (links to images to save space) - * APC settings, note Fragmentation: 0% and Cache full count is 0. https://i.stack.imgur.com/i0TrK.png * nginx.conf
user www-data;
worker_processes 4;
error_log /var/log/nginx/error.log;
pid /var/run/nginx.pid;
events {
worker_connections 1024;
use epoll;
# multi_accept on;
}
http {
include /etc/nginx/mime.types;
server_names_hash_bucket_size 64;
access_log off; #/var/log/nginx/access.log;
sendfile on;
#tcp_nopush on;
keepalive_timeout 0;
#keepalive_timeout 65;
tcp_nodelay on;
gzip on;
gzip_disable "MSIE [1-6]\.(?!.*SV1)";
include /etc/nginx/conf.d/*.conf;
include /etc/nginx/sites-enabled/*;
}
- typical site configuration included in nginx.conf https://i.stack.imgur.com/I3Y4N.png
- my php5-fpm.conf is default, except pm.max_children = 30 from pm.max_children = 10.
- my php5 config is default, only edits are sendmail/postfix related
- ulimit -n shows 1024
What helps - The only relief I have had from this is by moving one of the two busier sites to its own VPS. Obviously I would love to have all the sites on one vps, as the system has more than enough resources. Am I hitting open file limit somewhere? I'm suspicious it may have something to do with something php related.
Pretty confident that this is a config issue somewhere. Not confident what it could be though, and have spent 48 hours attempting to research before posting this question.
