Advanced Use of WordPress Cache. In this speech I've shown many different caching mechanism provided by WordPress and how to make good use of them. You'll learn how to make a website resiliant,more performant and more profitable. Talk @ WordCamp Turin 2019 ====================== Sapevi che WordPress dispone già di un meccanismo di caching nativo e che ha molteplici utilizzi? In questo speech mostrerò come utilizzare i diversi meccanismi di caching offerti da WordPress per rendere un sito resiliente e performante anche in condizioni di altro traffico e in grado di generare maggiori profitti. Talk tenuto durante il WordCamp Torino 2019

1. FROM CACHE TO CA$H
ADVANCED USE OF WP CACHE
Wordcamp Torino - 6 Aprile 2019 - @andreacardinali - #wctrn

2. Andrea Cardinali
● WP Dev
● Web Performance Lover
● CEO @ Performize

3. TABLE OF
CONTENTS
1. QUICK INTRODUCTION
2. WHY
3. USE CASE
4. WP_OBJECT_CACHE
5. CASE STUDY
6. PAY ATTENTION
7. QUESTION TIME
Wordcamp Torino - 6 Aprile 2019 - @andreacardinali - #wctrn

4. In computing, a cache (/kæʃ/ kash,[1] )
is a hardware or software component
that stores data so that future requests
for that data can be served faster;
the data stored in a cache might be the
result of an earlier computation or a
copy of data stored elsewhere
Wordcamp Torino - 6 Aprile 2019 - @andreacardinali - #wctrn
https://en.wikipedia.org/wiki/Cache_(computing)

5. 4 KIND
OF CACHE
1. OPCACHE
2. BROWSER CACHE
3. PAGE CACHE
4. OBJECT CACHE
Wordcamp Torino - 6 Aprile 2019 - @andreacardinali - #wctrn

6. WHY
Wordcamp Torino - 6 Aprile 2019 - @andreacardinali - #wctrn

7. WEBSITE FAILURE FORMULA
while ($resources < MAX_RESOURCES)
{
foreach($users as $user)
{
foreach($user->pageview)
{
do_some_expensive_stuff();
do_some_queries();
$resources++;
}
}
}

9. WHY
Wordcamp Torino - 6 Aprile 2019 - @andreacardinali - #wctrn

14. WHY
4 ADVANTAGES
1. INCREASE
PERFORMANCE
2. SAVE TIME
3. INCREASE REVENUE
4. SAVE MONEY
Wordcamp Torino - 6 Aprile 2019 - @andreacardinali - #wctrn

15. WHEN
5 TYPICAL USE CASE
1. HIGH TRAFFIC
2. CONCURRENT ACCESS
3. DYNAMIC CONTENT
4. TIME CONSUMING
OPERATIONS
5. CPU EXPENSIVE
OPERATIONS
6. (...)
Wordcamp Torino - 6 Aprile 2019 - @andreacardinali - #wctrn

16. HOW MANY OF YOU ARE USING
WORDPRESS CACHE?
Wordcamp Torino - 6 Aprile 2019 - @andreacardinali - #wctrn

17. YOU ARE ALREADY USING CACHE
Wordcamp Torino - 6 Aprile 2019 - @andreacardinali - #wctrn

18. wp_cache_*
One function to rule them all
get_post_ meta
get_user_meta
get_term_meta
get_site_meta
get_metadata($object_type,
$object_id, $key, $single
);
wp_cache_get()
$wp_object_cache->get(
$key,...)
Wordcamp Torino - 6 Aprile 2019 - @andreacardinali - #wctrn

19. WP OBJECT
CACHE
1. extends
WP_Object_Cache
2. mu-plugin
3. wp-content/object-
cache.php
Wordcamp Torino - 6 Aprile 2019 - @andreacardinali - #wctrn
https://codex.wordpress.org/Class_Reference/WP_Object_Cache

20. WP OBJECT
CACHE
1. SINCE 2005
2. BASE CLASS TO
PROVIDE LAYER FOR
CACHE
3. VOLATILE / NON
PERSISTENT
(BY DEFAULT)
Wordcamp Torino - 6 Aprile 2019 - @andreacardinali - #wctrn
https://codex.wordpress.org/Class_Reference/WP_Object_Cache

21. CASE STUDY
tourism website
● DYNAMIC COUNTERS
(OFFERS, PHOTOS,
REVIEWS)
● DYNAMIC PRODUCT
LIST
(SEARCH FILTERS)
● NO PAGINATION / NO
INFINITE SCROLL
Wordcamp Torino - 6 Aprile 2019 - @andreacardinali - #wctrn

23. Test Page Load Queries
no cache 5,3 2400
no cache +
get_post_meta
2,5 1212
cache + get_post_meta 0,7 99
FRAGMENT CACHING 0,227 188

25. -95%
PAGE LOAD TIME

26. -92%
TOTAL QUERIES

27. FRAGMENT
CACHING
● USEFUL TO STORE
PIECES (FRAGMENTS)
OF PAGE
● NOT AVAILABLE OUT
OF THE BOX
● PERFORMANCE HUGE
IMPROVEMENTS
Wordcamp Torino - 6 Aprile 2019 - @andreacardinali - #wctrn

28. FRAGMENT
CACHING
<?php
$html= get_post_meta($post_id,
'my_cache_key',true);
if(empty($html))
{
$html=ob_start();
//expensive stuff
$html=ob_get_clean();
add_post_meta($post_id,
'my_cache_key',$html,true);
}
echo $html;
Wordcamp Torino - 6 Aprile 2019 - @andreacardinali - #wctrn

29. PAY
ATTENTION
TO
● TRANSIENT EXPIRATION
● WP_Query
● CACHE INCONSISTENCY
● CACHE PRIMING
Wordcamp Torino - 6 Aprile 2019 - @andreacardinali - #wctrn

30. YOU CAN’T FIX
PERFORMANCE
WITH JUST A PLUGIN
Wordcamp Torino - 6 Aprile 2019 - @andreacardinali - #wctrn

31. CACHE IS A FULL STACK
Wordcamp Torino - 6 Aprile 2019 - @andreacardinali - #wctrn

32. BIG WIN EXISTS
BUT
THERE ARE
NO QUICK FIXES
Wordcamp Torino - 6 Aprile 2019 - @andreacardinali - #wctrn

33. THANK YOU!
Andrea Cardinali
andrea@performize.it
Wordcamp Torino - 6 Aprile 2019 - @andreacardinali - #wctrn

34. I’M HIRING
● WP DEV
● WOOCOMMERCE DEV
● WEB PERFORMANCE
ADDICTED
● REMOTE WORKING
Wordcamp Torino - 6 Aprile 2019 - @andreacardinali - #wctrn
https://www.performize.it/jobs/

35. PLUGINS
● SG Optimizer
● WP Redis
● WP Memcached
● Hyper DB
Wordcamp Torino - 6 Aprile 2019 - @andreacardinali - #wctrn