Un-Scaling WordPress

WordPress can scale from a few visitors per day to millions. While it can be complicated to get WordPress to run in a clustered setup, most sites don’t need this.

While developing WordPress managed hosting, one of the discoveries was that WordPress can not only scale, but it can handle millions of visits per month with a single web machine and MySQL.

I’ll walk through the basics of performance in WordPress, and what it takes to build a highly performing install on a single VPS + MySQL, dispelling the myth that it requires a large amount of resources to handle a huge amount of traffic with WordPress.

Transcript

1. Un-Scaling WordPress
   WordCamp DC 2017
   Mike Schroder
   Director of WordPress Strategy @ DreamHost
   @GetSource - https://getsource.net
   

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2. What does it mean to scale?
   

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3. Vertical scaling:
   More RAM and CPU.
   

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4. Horizontal scaling:
   More servers with the RAM and CPU.
   

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5. Vertical scaling
   

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6. Vertical scaling
   

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7. Horizontal scaling
   

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8. Horizontal scaling
   

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9. What does it mean to un-scale?
   

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11. Simplified architecture.
    

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12. Let’s see what we can do with
    shared and a 512mb VPS.
    

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13. How much RAM does
    WordPress need?
    

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14. Page View => ~3-120mb
    Image Operations => ~256mb+
    

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15. Does WordPress scale?
    

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16. Adjacent technologies help WordPress
    serve higher traffic sites well.
    

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17. We’re really talking about caching.
    

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18. If you’ve hit PHP, you’ve lost.
    

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19. But it’s not as bad as it used to be.
    

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20. Opcode cache.
    

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21. Usually OPcache,
    included with PHP 5.5+
    

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22. Higher percentage of improvement
    on hosts with low CPU resources.
    

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23. Test: ~100 users during 1 minute.
    

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24. Shared PHP 5.6
    100/min
    Average:
    1045ms
    

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25. Shared PHP 5.6 w/OPcache
    100/min
    Average:
    782ms
    

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26. Shared PHP 7
    100/min
    Average:
    760ms
    

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27. Shared PHP 7 w/OPcache
    100/min
    Average:
    507ms
    

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28. Persistent object caching.
    

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29. By default, WP’s internal cache
    expires with each request.
    

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30. Persistent object caching
    helps dynamic sites most.
    

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31. Usually this is
    Memcached or Redis.
    

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32. Front end caching.
    

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33. Save the final output of PHP.
    

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34. Disk, Varnish, Nginx.
    

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35. Front end caching
    helps static sites most.
    

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36. Shared PHP 7 w/OPcache + WP Super Cache
    PHP Routed:
    100/min
    Average:
    69ms
    

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37. Like with “firewall” plugins,
    treat PHP-based solutions
    with skepticism.
    

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38. Shared PHP 7 w/OPcache + WP Super Cache
    Disk Backed:
    100/min
    Average:
    32ms
    

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39. Shared PHP 7 w/OPcache + WP Super Cache
    Disk Backed:
    1000/min
    Average:
    43ms
    

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40. Shared PHP 7 w/OPcache + WP Super Cache
    Disk Backed:
    5000/min
    Average:
    2158ms
    

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41. Let’s take a look at our VPS.
    

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42. VPS PHP 7 w/OPcache
    100/min
    Average:
    169ms
    

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43. VPS PHP 7 w/OPcache + Varnish
    RAM Backed
    100/min
    Average:
    21ms
    

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44. VPS PHP 7 w/OPcache + Varnish
    RAM Backed
    5000/min
    Average:
    17ms
    

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45. 5000/min => 216,000,000/month
    

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46. How much RAM do
    adjacent services need?
    

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47. Basically anything helps for OPcache.
    So have some.
    

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48. 32-96mb for Memcached,
    with slab size > than options.
    (4mb is a good start)
    

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49. 128mb Varnish
    Have some VCL.

    https://github.com/tollmanz/varnish-vcl-collection
    

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50. Thanks!
    Mike Schroder
    @GetSource
    https://getsource.net
    Director of WordPress Strategy @ DreamHost
    

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