So, my server was doing fine, but recently my Wordpress has been getting a lot of 502 and 504 errors – mostly when making updates to the site. I think it’s a PHP-FPM issue and perhaps how my server is configured since I’ve upgraded a couple times and it should be blazing fast – I have the 4GB / 60 GB / 4TB option.
@jtittle I saw you were an expert in this kind of thing.
Here’s my nginx.conf:
worker_processes 4; worker_rlimit_nofile 20480;
pid /var/run/nginx.pid;
events { worker_connections 2048;
use epoll;
multi_accept on;
}
http { set_real_ip_from 127.0.0.1; real_ip_header X-Forwarded-For;
server_names_hash_bucket_size 64;
server_name_in_redirect off;
include /etc/nginx/mime.types;
default_type application/octet-stream;
access_log off;
error_log /var/log/nginx/error.log;
keepalive_timeout 65;
keepalive_requests 100000;
sendfile on;
tcp_nopush on;
tcp_nodelay on;
types_hash_max_size 2048;
client_body_buffer_size 128k;
client_max_body_size 24m;
client_header_buffer_size 1k;
large_client_header_buffers 4 4k;
output_buffers 1 32k;
postpone_output 1460;
client_header_timeout 3m;
client_body_timeout 3m;
send_timeout 3m;
open_file_cache max=1000 inactive=20s;
open_file_cache_valid 30s;
open_file_cache_min_uses 5;
open_file_cache_errors off;
gzip on;
gzip_vary on;
gzip_min_length 1000;
gzip_types
application/x-javascript
application/javascript
text/css
text/javascript
text/plain
text/xml
application/json
application/vnd.ms-fontobject
application/x-font-opentype
application/x-font-truetype
application/x-font-ttf
application/xml font/eot
font/opentype font/otf
image/svg+xml
image/vnd.microsoft.icon;
gzip_disable "MSIE [1-6]\.";
log_format main '$remote_addr - $remote_user [$time_local] '
'"$request" $status $bytes_sent '
'"$http_referer" "$http_user_agent" '
'"$gzip_ratio"';
log_format download '$remote_addr - $remote_user [$time_local] '
'"$request" $status $bytes_sent '
'"$http_referer" "$http_user_agent" '
'"$http_range" "$sent_http_content_range"';
map $status $loggable {
~^[23] 0;
default 1;
}
server_tokens off;
#include /etc/nginx/naxsi_core.rules;
server {
listen 80;
listen 443 ssl http2;
server_name www.nerdlouisville.org *.nerdlouisville.com;
ssl_protocols TLSv1 TLSv1.1 TLSv1.2; ssl_ciphers 'ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES256-GCM-SHA384:DHE-RSA-AES128-GCM-SHA256:DHE-DSS-AES128-GCM-SHA256:kEDH+AESGCM:ECDHE-RSA-AES128-SHA256:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA:ECDHE-ECDSA-AES128-SHA:ECDHE-RSA-AES256-SHA384:ECDHE-ECDSA-AES256-SHA384:ECDHE-RSA-AES256-SHA:ECDHE-ECDSA-AES256-SHA:DHE-RSA-AES128-SHA256:DHE-RSA-AES128-SHA:DHE-DSS-AES128-SHA256:DHE-RSA-AES256-SHA256:DHE-DSS-AES256-SHA:DHE-RSA-AES256-SHA:AES128-GCM-SHA256:AES256-GCM-SHA384:AES128-SHA256:AES256-SHA256:AES128-SHA:AES256-SHA:AES:CAMELLIA:DES-CBC3-SHA:!aNULL:!eNULL:!EXPORT:!DES:!RC4:!MD5:!PSK:!aECDH:!EDH-DSS-DES-CBC3-SHA:!EDH-RSA-DES-CBC3-SHA:!KRB5-DES-CBC3-SHA';
ssl_prefer_server_ciphers on;
ssl_certificate /etc/letsencrypt/live/nerdlouisville.org/fullchain.pem;
ssl_certificate_key /etc/letsencrypt/live/nerdlouisville.org/privkey.pem;
ssl_trusted_certificate /etc/letsencrypt/live/nerdlouisville.org/chain.pem;
ssl_session_cache shared:SSL:128m;
ssl_session_timeout 1d;
add_header Strict-Transport-Security "max-age=31557600; includeSubDomains";
add_header X-Frame-Options "SAMEORIGIN" always;
add_header X-Content-Type-Options "nosniff" always;
add_header X-Xss-Protection "1";
ssl_stapling on;
ssl_stapling_verify on;
resolver 8.8.8.8;
return 301 https://nerdlouisville.org$request_uri;
}
server {
server_name nerdlouisville.org nerdlouisville.com;
listen 80;
return 301 https://nerdlouisville.org$request_uri;
}
server {
listen 443 ssl http2;
server_name nerdlouisville.org;
ssl_protocols TLSv1 TLSv1.1 TLSv1.2; ssl_ciphers 'ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES256-GCM-SHA384:DHE-RSA-AES128-GCM-SHA256:DHE-DSS-AES128-GCM-SHA256:kEDH+AESGCM:ECDHE-RSA-AES128-SHA256:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA:ECDHE-ECDSA-AES128-SHA:ECDHE-RSA-AES256-SHA384:ECDHE-ECDSA-AES256-SHA384:ECDHE-RSA-AES256-SHA:ECDHE-ECDSA-AES256-SHA:DHE-RSA-AES128-SHA256:DHE-RSA-AES128-SHA:DHE-DSS-AES128-SHA256:DHE-RSA-AES256-SHA256:DHE-DSS-AES256-SHA:DHE-RSA-AES256-SHA:AES128-GCM-SHA256:AES256-GCM-SHA384:AES128-SHA256:AES256-SHA256:AES128-SHA:AES256-SHA:AES:CAMELLIA:DES-CBC3-SHA:!aNULL:!eNULL:!EXPORT:!DES:!RC4:!MD5:!PSK:!aECDH:!EDH-DSS-DES-CBC3-SHA:!EDH-RSA-DES-CBC3-SHA:!KRB5-DES-CBC3-SHA';
ssl_prefer_server_ciphers on;
ssl_certificate /etc/letsencrypt/live/nerdlouisville.org/fullchain.pem;
ssl_certificate_key /etc/letsencrypt/live/nerdlouisville.org/privkey.pem;
ssl_trusted_certificate /etc/letsencrypt/live/nerdlouisville.org/chain.pem;
ssl_session_cache shared:SSL:128m;
ssl_session_timeout 1d;
add_header Strict-Transport-Security "max-age=31557600; includeSubDomains";
add_header X-Frame-Options "SAMEORIGIN" always;
add_header X-Content-Type-Options "nosniff" always;
add_header X-Xss-Protection "1";
ssl_stapling on;
ssl_stapling_verify on;
resolver 8.8.8.8;
if ($http_user_agent ~ "MSIE" ) {
return 303 https://browser-update.org/update.html;
}
charset utf-8;
root /var/www/html;
index index.php index.html index.htm;
location / {
try_files $uri $uri/ /index.php?q=$uri&$args;
}
location /forum {
try_files $uri @vanilla;
}
location @vanilla {
rewrite ^/forum(/.*) /forum/index.php?p=$uri&$args last;
}
location ~* \.(jpg|jpeg|gif|png|css|js|ico|xml)$ { expires 5d; }
location = /favicon.ico { access_log off; log_not_found off; }
location = /robots.txt { access_log off; log_not_found off; }
location ~ /\. { log_not_found off; deny all; }
location ~ \.php$ {
include snippets/fastcgi-php.conf;
fastcgi_pass unix:/run/php/php7.0-fpm.sock;
}
}
upstream backend {
server 127.0.0.1:4567 weight=1;
}
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Accepted Answer
The error in the PHP-FPM log:
server reached pm.max_children
When this happens, generally PHP-FPM will restart, which will cause a failed connection if NGINX is attempting to connect at the same time. We can up the limits on this setting as well as others in the www.conf file.
I’d make a backup of your www.conf file:
cp /etc/php/7.0/fpm/pool.d/www.conf /usr/local/src/www.conf
Then modify these values in /etc/php/7.0/fpm/pool.d/www.conf
pm.max_children = 16
pm.start_servers = 8
pm.min_spare_servers = 6
pm.max_spare_servers = 12
That’ll raise the default limits to more usable limits, though depending on traffic and what you’re running, those may need to increase. Generally, all values I use are divisible by 2 (i.e. I won’t use 5, 7, 9, etc) to prevent odd rounding. Details on how to set pm.start_servers is in the configuration comments as well to give you an idea of what it should be set to.
You’d then need to restart PHP-FPM:
service php7.0-fpm restart
Please supply the last lines from your error log from when the error happened:
tail -20 /var/log/nginx/error.log
And can you also post your PHP-FPM pool configuration, since you’re most likely either exceeding the memory limit or timeout.
/etc/php/7.0/fpm/pool.d/www.conf
Here’s my fastcgi.conf
fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
fastcgi_param QUERY_STRING $query_string;
fastcgi_param REQUEST_METHOD $request_method;
fastcgi_param CONTENT_TYPE $content_type;
fastcgi_param CONTENT_LENGTH $content_length;
fastcgi_param SCRIPT_NAME $fastcgi_script_name;
fastcgi_param REQUEST_URI $request_uri;
fastcgi_param DOCUMENT_URI $document_uri;
fastcgi_param DOCUMENT_ROOT $document_root;
fastcgi_param SERVER_PROTOCOL $server_protocol;
fastcgi_param REQUEST_SCHEME $scheme;
fastcgi_param HTTPS $https if_not_empty;
fastcgi_param GATEWAY_INTERFACE CGI/1.1;
fastcgi_param SERVER_SOFTWARE nginx/$nginx_version;
fastcgi_param REMOTE_ADDR $remote_addr;
fastcgi_param REMOTE_PORT $remote_port;
fastcgi_param SERVER_ADDR $server_addr;
fastcgi_param SERVER_PORT $server_port;
fastcgi_param SERVER_NAME $server_name;
# PHP only, required if PHP was built with --enable-force-cgi-redirect
fastcgi_param REDIRECT_STATUS 200;
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