The Need For Speed: Caching Fundamentals

The Need For Speed:
Caching Fundamentals
Frankie Jarrett
@fjarrett

About me
• Working with WordPress professionally since 2007
• Engineering Manager at GoDaddy
• Oversee Managed WordPress hosting products
• Working in tech remotely for 7 years
• Based in St. Joseph, Missouri
Copyright© 2018 GoDaddy Inc. All Rights Reserved.2

Why should we care about
websites being fast?
3 Copyright© 2018 GoDaddy Inc. All Rights Reserved.
• Higher user engagement
• Time is money
• Bandwidth costs
• Because Google cares

Caching is a temporary copy of
data that can be served faster
than the original source.

Caching Layers
(yeah, it’s complicated)

Transient cache
Key/value storage for data that should be
checked for changes on a regular interval
(expires), or is expensive to fetch (no expiration).
• Theme/plugins updates
• Filesystem directories
• News feeds
• Complex MySQL queries (no persistent object
cache)
get_transient( $key );
set_transient( $key, $value, $ttl );
delete_transient( $key );
var_export(
get_site_transient('update_plugins')
);
stdClass(
'last_checked' => 1523054292,
response => array (
'update_available' => array(
'akismet/akismet.php’ => ...
...
)
)
)

Object cache
Key/value cache for expensive queries made to
the MySQL database. WordPress can be
extended to make it’s object cache persistent.
• APCu
• Redis
• Memcached
wp_cache_get( $key, $group, $force );
wp_cache_set( $key, $value, $group, $ttl );
wp_cache_delete( $key, $group );
wp_cache_incr( $key, $group );
var_export( wp_cache_get() );
stdClass(
'last_checked' => 1523054292,
response => array (
'update_available' => array(
'akismet/akismet.php’ => ...
...
)
)
)

Page cache (proxy/HTTP/static)
Serve dynamic content as static HTML.
• Varnish
• Apache Trafficserver
• Squid Proxy
• NGINX + FastCGI

PHP OPCache
Store pre-interpreted PHP bytecode (opcode) in
memory.
• Preceded by APC
• Created by the Zend group
• Added to PHP core in 5.5
opcache.enable = 1
php.ini

CDN
Reduce network round-trip time for assets called
on a page, such as images, JavaScript and CSS.
• CloudFlare
• AWS CloudFront
• Sucuri WAF
• Akamai
• Jetpack Photon (images only)

Minification
Remove whitespace characters from JavaScript,
CSS, or HTML.
Some minification tools can also modify the code
to make it less redundant and use shorthand.
function sum(num1, num2) {
return num1 + num2;
}
function sum(A,B){return A+B;}
BEFORE
AFTER

Concatenation
Chain the contents of JavaScript and CSS files
together and fetch the asset in a single request.

Waterfall view

The Need For Speed: Caching Fundamentals

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