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A look at the modern
WordPress server stack
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Carl Alexander
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@twigpress
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carlalexander.ca
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No content
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Story time
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A fast WordPress server:
Linux + Apache + MySQL + PHP
Once upon a time…
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Those were the “good ol’ days”!
Once upon a time…
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Things were simpler then…
Once upon a time…
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Everything has to load fast!
Nowadays…
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Nowadays…
Or there are consequences…
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Nowadays…
So the WordPress server evolved
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The stack
Nowadays…
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Request
Response
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Request / Response
Request / Response
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Request / Response
HTTP
Request
Web Server
Browser
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Request / Response
HTTP
Response
Web Server
Browser
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Request / Response
First HTTP response:
Always HTML content
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Request / Response
Follow up HTTP requests:
Required files (e.g. CSS, JS, images)
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Request / Response
Cycle continues until
browser can render the page
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Request / Response
The faster it happens,
the faster your website loads
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Optimizing the cycle
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Optimizing the cycle
Can't just make a web server faster
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Optimizing the cycle
Web server is also a dispatcher
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Optimizing the cycle
Forwards requests
to other services (like PHP)
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Optimizing the cycle
We need to
receive as few requests
as possible
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Optimizing the cycle
We need to
forward as few requests
as possible
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Cycle stack elements
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Web server
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Web server
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Web server
Three players. 90% market share.
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Apache: The old guard
Web server
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IIS: The Microsoft solution
Web server
(You can ignore this one!)
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nginx: The new kid
Web server
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Used by
Automattic since 2008
Web server
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Used by
top hosting companies
Web server
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Used by
high-end WordPress agencies
Web server
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Built to handle a lot of traffic
Web server
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HTTP cache
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HTTP cache
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Most important
element of the stack
HTTP cache
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A web server is pretty dumb
HTTP cache
(Well, by default)
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Always forwards requests to PHP
HTTP cache
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PHP often generates
the same response
HTTP cache
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That’s terrible!
HTTP cache
(PHP is our bottleneck)
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HTTP cache solves this problem
HTTP cache
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Caches responses from PHP
HTTP cache
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Drastic reduction in cycle time
HTTP cache
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Has the widest range of options
HTTP cache
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Easiest option:
Install a page caching plugin
HTTP cache
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HTTP cache
• Batcache
• Hyper Cache
• WP Rocket
• WP Super Cache
• W3 Total Cache
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Middle option:
Have the web server do it
HTTP cache
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Hardest option:
Add Varnish to the stack
HTTP cache
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Questions
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Optimizing PHP
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Optimizing PHP
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No cached response to send back
Optimizing PHP
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Time for WordPress to do its thing
Optimizing PHP
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Turns our request into a response
Optimizing PHP
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PHP is the bottleneck
Optimizing PHP
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Latest PHP version
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Minimum requirement: PHP 5.2
PHP version
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Almost 10 years old!
(No support since 2011)
PHP version
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PHP team hasn't been sitting idle
PHP version
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Largest improvement was
from 5.3 to 5.4
(Ignoring PHP 7)
PHP version
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Opcode caching
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PHP compiles a script
each time it executes it
Opcode caching
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Caches compiled PHP code
Opcode caching
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Not bundled with PHP before 5.5
Opcode caching
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Next generation PHP
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Two new PHP compilers:
HHVM and PHP 7
WordPress
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Both built from the ground up
WordPress
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Incredible performance gains
WordPress
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Good news:
WordPress 100% compatible
WordPress
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Bad news:
Not all plugins or themes are
WordPress
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Always have a fallback to PHP 5
WordPress
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Questions
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Query
Result
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Query / Result
Query / Result
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PHP files don't contain any data
Query / Result
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WordPress stores all its data
in a MySQL database
Query / Result
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Query / Result
Query
Database
Server
WordPress
(PHP)
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Query / Result
Result
Database
Server
WordPress
(PHP)
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Can happen a few dozen times
to a few hundred times
Query / Result
(Talk with your developer(s) if it's the latter!)
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Optimizing the cycle
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Database queries take time
Optimizing the cycle
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Slows down PHP execution
Optimizing the cycle
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Can’t always control how many
queries WordPress needs to do
Optimizing the cycle
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We need to make PHP
wait as little as possible
Optimizing the cycle
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Cycle stack elements
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Database server
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Database server
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MySQL database != MySQL server
Database server
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Multiple forked versions now
Database server
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No performance difference
between versions
Database server
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Storage engines are
what impact performance
Database server
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They control data management
Database server
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WordPress default: MyISAM
Database server
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Better choice: InnoDB
Database server
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Object cache
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Object cache
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Stores fetched or generated data
Object cache
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WordPress uses it a lot
Object cache
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Less database queries
Object cache
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But data doesn’t persist by default
Object cache
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Data can stay valid for a long time
Object cache
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Use a persistent object cache
Object cache
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Connects the object cache to a
persistent data store
Object cache
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Two popular data store options
Object cache
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Memcached: The old favourite
Object cache
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Redis: The new hotness
Object cache
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Doing it yourself
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DebOps for WordPress
Doing it yourself
• HHVM
• MariaDB
• nginx
• Redis
• Varnish
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EasyEngine
Doing it yourself
• MariaDB
• nginx
• Various object cache options
• Various HTTP cache options
• Various PHP options
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Trellis
Doing it yourself
• MariaDB
• Memcached
• nginx
• nginx HTTP cache (optional)
• PHP 7
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Questions
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Thank you!