Scaling WordPress

I came to this talk from the perspective of a plugin developer rather than a site maintainer so not all of the content was completely applicable to me. However, there were a few bits of information about WordPress that I found very useful and I walked away with affirmation that the approach we have been taking in our plugin is a good one from a scalability perspective. Overall Zack was a good presenter and had a well composed slide deck. I would attend another talk by Zack.

My notes for this talk can be found below:

  • page caching – turn wordpress into a static site, mic drop
  • caching reduces site load
  • page caching – batcache, varnish
  • edge caching – a service, cdn, fastly, cloud flare
  • low TTL to avoid invalidation pains – 5 mins is a good compromise
  • diagnose issues in the code that might be contributing to bad performance
  • use your experience and tools
  • database queries are most likely the bottle neck – especially with poorly written plugins
  • remote requests can create a lot of latency – especially if the remote server is slow
  • slow methods – looping/recursion
  • WP plugin: Query Monitor – has section for “slow queries” greater than 100ms
  • XHProf/XDebug – if you have access to the server
  • New Relic – service
  • Treat with object caching – WP_Object_Cache class, wp_cache_set, wp_cache_get
  • object caching analogy – grocery shopping
  • write your own WP_Object_Cache for better performance – memcached, apc (not meant for this)
  • use transient API if you are a plugin or theme developer and don’t have control of the server
  • transient API will use the WP_Object_Cache
  • proactive approach – only cache events that will be reused opposed to caching the entire page
  • proactive approach – update cached content via scheduled events
  • stale while revalidate – if a user request old data serve it to them but initiation a background process to update the old data
  • prevent scaling issues with a solid stack
  • edge network -> load balancer -> page caching -> web server -> persistence layer and object cache
  • separate admin traffic from public traffic
  • object cache + page cache = happy life
  • https://tollmanz.com/mwphp15
  • from wired