Hi All,

We recently migrated from apache to nginx.

OS - CetnOS 6
Nginx - 1.62 (4 CPU 8 GB RAM)
PHP-FPM (php 5.4.37) (4 CPU 8 GB RAM)
APC (Code Cache APC 3.1.13 beta)
Memcache (data cache)

I have upstream of 4 php servers for php-fpm service.

I am facing two issues:

1. I am getting 502 status code in access log means nginx generating 502 bad gateway error

2. Randomly connections got pile up on nginx up to 2500 and on php-fpm servers we do not see any load in top only 1-2 process seems to be running during that time and without taking any restart after 2-3 minutes it starts working normally and connections goes down to normal without taking any restart.


Please check nginx configuration in-line

user nguser;
worker_processes 4;

pid /var/run/nginx.pid;
worker_rlimit_nofile 70000;

events {
worker_connections 1024;
multi_accept on;
use epoll;
}

http {
##
# Basic Settings
##

sendfile on;
tcp_nopush on;
tcp_nodelay on;
keepalive_requests 1000;
keepalive_timeout 65;
send_timeout 15;
types_hash_max_size 2048;
server_tokens off;
client_max_body_size 50M;
client_body_buffer_size 1m;
client_body_timeout 15;
client_header_timeout 15;
server_names_hash_bucket_size 64;
server_name_in_redirect off;

include /etc/nginx/mime.types;
default_type application/octet-stream;

##
# Logging Settings
##
#access_log on;

access_log /var/log/nginx/access.log combined;
#error_log /dev/null crit;
error_log /var/log/nginx/error.log error;


#gzip on;
gzip on;
gzip_static on;
gzip_disable "msie6";
gzip_vary on;
gzip_proxied any;
gzip_comp_level 6;
gzip_min_length 512;
gzip_buffers 16 8k;
gzip_http_version 1.1;
gzip_types text/css text/javascript text/xml text/plain text/x-component
application/javascript application/x-javascript application/json
application/xml application/rss+xml font/truetype application/x-font-ttf
font/opentype application/vnd.ms-fontobject image/svg+xml;

open_file_cache max=2000 inactive=20s;
open_file_cache_valid 60s;
open_file_cache_min_uses 5;
open_file_cache_errors off;

fastcgi_buffers 256 16k;
fastcgi_buffer_size 128k;
fastcgi_busy_buffers_size 256k;
fastcgi_temp_file_write_size 256k;
fastcgi_connect_timeout 300;
fastcgi_send_timeout 300;
fastcgi_read_timeout 300;
fastcgi_intercept_errors on;
reset_timedout_connection on;

upstream fastcgiservers {
least_conn;
server xxx.xxx.xx.xx:9000;
server xxx.xxx.xx.xx:9000;
server xxx.xxx.xx.xx:9000;
server xxx.xxx.xx.xx:9000;
}

include /etc/nginx/conf.d/*.conf;
include /etc/nginx/sites-enabled/*;
}

location ~ \.php$ {
try_files $uri =404;
include fastcgi_params;
fastcgi_pass fastcgiservers;
fastcgi_index index.php;
fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
}

---------------------------------------------------------PHP-FPM Settings ------------------------------------------------------------------

pm.max_children = 150
pm.start_servers = 90
pm.min_spare_servers = 70
pm.max_spare_servers = 100
pm.max_requests = 1500

Any help or suggestion would be greatly appreciated.

Thanks