502 Error Issue

[mudgil.gaurav]

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

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,259833,259833#msg-259833