This document provides tips and best practices for optimizing a WordPress site hosted on a VPS. It recommends switching from the default PHP implementation to PHP-FPM to improve performance. It also recommends replacing the default web server with Nginx, and describes various Nginx configuration options to optimize caching, compression, and resource usage. These include enabling OPcache and using Nginx as a reverse proxy for caching and serving static files. The document also covers using Nginx fastcgi caching to cache dynamic PHP pages from WordPress for better performance.

1. 10 Million hits a day
with WordPress using a $15 VPS

2. $ whoami
Paolo Tonin
Sysadmin @bakeca.it

4. Starting a new
WordPress Project is
straightforward

5. 10 minutes setup
deployed on a simple VPS

6. 10 minutes setup

7. Your website become popular

10. No Silver Bullet!

11. Modernize our
stack

12. Modernize our stack
From

13. Modernize our stack
To LEMP

14. #1 PHP Optimization

15. Switch over
PHP-FPM

16. #1 PHP-FPM
PHP-FPM (FastCGI Process Manager) is an alternative
PHP FastCGI implementation with some additional
features useful for sites of any size, especially
busier sites.
* Built in from PHP 5.4

17. #1 PHP-FPM
$ sudo apt-get install -y php7.1-fpm
$ sudo yum install -y php-fpm
# ps fax | grep fpm
833 ? Ss 0:08 php-fpm: master process
(/etc/php-fpm.conf)
1778 ? S 0:02 _ php-fpm: pool www
1779 ? S 0:02 _ php-fpm: pool www
1780 ? S 0:02 _ php-fpm: pool www
1781 ? S 0:02 _ php-fpm: pool www

18. Let’s dive into
some details

20. #1 PHP-FPM
pm = dynamic
Similar to Apache prefork

21. #1 PHP-FPM
pm = ondemand
Ideal for hosting many
small websites with small
amount of request

22. #1 PHP-FPM
pm = static
Fixed php-fpm process
number to archieve your
server’s max performance

23. #1 PHP-FPM
; /etc/php-fpm.d/www.conf
[www]
pm = static
pm.max_children = 10
user = sitename
group = sitename
; listen on unix socket over tcp socket
listen = /var/run/php-fpm/sitename-php-fpm.sock
listen.owner = sitename
listen.group = nginx
listen.mode = 0660

24. ; /etc/php-fpm.d/www.conf
; try to avoid memory leaks, it enables php-fpm
process respawning
pm.max_requests = 700
; audit slow request with stack trace log
slowlog = /var/log/php-fpm/sitename-slow.log
request_slowlog_timeout = 30s
; similar to “max_execution_time”, it has more
priority than php.ini max_execution_time
request_terminate_timeout = 180
; log PHP Warning, Error, Fatal (not by default)
catch_workers_output = yes

25. #1.1 PHP Optimization
PHP 7 + OpCache

26. ; enable-opcache-file
; php.ini
opcache.memory_consumption = 512
opcache.max_accelerated_files = 10000
opcache.interned_strings_buffer = 128
opcache.file_cache = /var/tmp
opcache.huge_code_pages =1
; php-cli.ini for WP-CLI and cronjobs
opcache.enable_cli = 1
opcache.file_cache = /var/tmp
opcache.file_cache_only = 1
#1.1 PHP OpCache

27. #1.1 PHP OpCache
; sysctl.conf
; enable hugepages, PHP7 only
vm.nr_hugepages = 512
# cat /proc/meminfo | grep Huge
AnonHugePages: 6144 kB
HugePages_Total: 512
HugePages_Free: 300
HugePages_Rsvd: 0
HugePages_Surp: 0
Hugepagesize: 2048 kB

28. #1.1 PHP OpCache
# ps ef -o command,vsize,rss,size -C php-fpm
COMMAND VSZ RSS SIZE
php-fpm: master process (/e 933836 278428 6204
_ php-fpm: pool www 1031728 42692 92916
_ php-fpm: pool www 1026596 40596 87784
_ php-fpm: pool www 1025452 37780 86640
_ php-fpm: pool www 1026252 35368 87440
Check php-fpm Memory Consumption
40MB * 50 php-fpm processes = 2GB RAM

29. #2 Replace webserver
245 million
total sites and counting…
running on NGINX

30. #2 Replace webserver
Many config examples on
https://www.nginx.com/resources/
wiki/start/index.html

31. #2 Replace webserver
* Netcraft Sept 2017

32. #2.1 nginx
System config limits
# /etc/security/limits.conf
# overrides ulimit values
#<domain> <type> <item> <value>
nginx hard nofile 100000
nginx soft nofile 100000

33. #2.1 nginx
Nginx config limits
# nginx.conf
user nginx;
worker_processes auto;
worker_rlimit_nofile 10000;
events {
worker_connections 16384;
multi_accept on;
use epoll;
}

34. #2.1 nginx
Gzip compression
# nginx.conf (continue)
gzip on;
gzip_disable "msie6";
gzip_vary on;
gzip_proxied any;
gzip_comp_level 6;
gzip_min_length 256;
gzip_buffers 32 8k;

35. #2.1 nginx
Limit filesystem activity for
static contents
# nginx.conf (continue)
open_file_cache max=10000 inactive=10s;
open_file_cache_valid 20s;
open_file_cache_min_uses 2;
open_file_cache_errors on;

36. #2.2 nginx
Nginx as reverse proxy

37. #2.2 nginx
HTTP Caching primer

38. Expires: contains the datetime after which
the response is considered stale. It has
priority over Cache-Control
Cache-Control: used to specify directives for
caching mechanism in both, request and
response

39. Last-Modified: contains the date and time
at which the origin server believes the
resource was last modified. HTTP dates are
always expressed in GMT
ETag: it’s an identifier for a specific version
of a resource

40. proxy_cache_path /tmp/cache keys_zone=one:10m levels=1:2
inactive=60m;
server {
listen 80;
server_name mywordpressdomain.com
location / {
proxy_pass http://localhost:8080
proxy_cache one;
}
}
#2.2 nginx
HTTP Caching primer

41. add_header X-Cache-Status $upstream_cache_status
MISS Response not found in cache; go to upstream
and save the results in the cache
STALE Serve the stale content from the cache,
because the upstream is not responding correctly
HIT Serve valid content, fresh content direct from
cache
#2.2 nginx
HTTP Caching instrumentation

42. proxy_cache_path /tmp/cache keys_zone=one:10m levels=1:2
inactive=60m;
server {
listen 80;
server_name mywordpressdomain.com
location / {
proxy_pass http://localhost:8080
proxy_cache one;
add_header X-Cache-Status $upstream_cache_status;
}
}
#2.2 nginx
HTTP Caching primer

43. PURGE verb is not supported
in the OSS version
$ curl -X PURGE -D - “http://domain.com/*"

44. Cache dynamic contents
with fastcgi-cache
(microcaching)
“Go Big or Go Home”

45. #2.3 nginx
php-fpm fastcgi cache
# ps fax | grep nginx
922 ? Ss 0:00 nginx: master process /usr/sbin/nginx -
c /etc/nginx/nginx.conf
3988 ? S 0:00 _ nginx: worker process
3989 ? S 0:00 _ nginx: worker process
3990 ? S 0:00 _ nginx: cache manager process
Cache Manager activated periodically to check the
state of the cache.
The cache manager removes the data that was
accessed recently as well the cache considered
inactive

46. #2.3 nginx
php-fpm fastcgi cache
; nginx.conf http block
upstream php-web {
server unix:/var/run/php-fpm/sitename.sock
weight=100;
server unix:/var/run/php-fpm/sitename.sock
weight=100;
}
fastcgi_cache_path /var/tmp/nginx-fastcgi-cache
levels=1:2 keys_zone=WPCACHE:100m max_size=1024m
inactive=1h;

48. #2.3 nginx
php-fpm fastcgi cache
; creates a cache version with these discriminants
fastcgi_cache_key
"$scheme$request_method$host$request_uri;
; at least 1 request to populate with a new cache
element
fastcgi_cache_lock on;
; consider stale response errors
fastcgi_cache_use_stale error timeout invalid_header
http_500;

49. #2.3 nginx
php-fpm fastcgi cache
; enables revalidation of expired cache with the
"If-Modified-Since" and "If-None-Match" header
fields.
fastcgi_cache_revalidate on;
; no cache for redirects
fastcgi_cache_valid 301 0;
fastcgi_cache_valid 3m;
; cache only GET http verb
fastcgi_cache_methods GET;

50. #2.3 nginx
php-fpm fastcgi cache
# WARNING: Ignore cache-control; without these
fcgi_cache doesn't works
fastcgi_ignore_headers Cache-Control Expires Set-
Cookie;
fastcgi_pass_header Cookie;

51. #2.3 nginx
php-fpm fastcgi cache
# WARNING: Ignore cache-control; without these
fcgi_cache doesn't works
fastcgi_ignore_headers Cache-Control Expires Set-
Cookie;
fastcgi_pass_header Cookie;

52. location ~ .php$ {
fastcgi_split_path_info ^(.+.php)(/.*)$;
fastcgi_param SCRIPT_FILENAME
$realpath_root$fastcgi_script_name;
fastcgi_param DOCUMENT_ROOT $realpath_root;
fastcgi_param HTTPS off;
fastcgi_intercept_errors on;
fastcgi_pass php-web;
# Enable fastcgi_cache
fastcgi_cache WPCACHE;
fastcgi_cache_bypass $no_cache;
fastcgi_no_cache $no_cache;
}

53. Bonus content

54. WordPress plugins
WP Offload S3 copies files from your WordPress
Media Library to Amazon S3 and rewrites URLs to
serve the files from S3, CloudFront, or another CDN
WP Offload S3

55. WordPress plugins
Replacement for wpdb class. It supports partition
of data as well as replication and read write splits
Used for commercial service wordpress.com

56. WordPress plugins
Cache database results into Memcached, it also
support integration with CDN providers

57. “Talk is cheap,
show me the code”
(cit. Linus Torvalds)

58. Demo