What we can learn from CDNs about Web Development, Deployment, and Performance
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CTO Tyler McMullen details what can be learned from CDNs when developing applications.
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What we can learn from CDNs about Web Development, Deployment, and Performance
- 1. What we can learn from CDNs about Web Development, Deployment, and Performance Tyler McMullen, CTO & Mad Scientist WebPerf Meetup, London March 1st
- 2. Lesson: People Use Their CDNs Wrong
- 3. CDNs offer a toolset • The black box approach isn’t always good • Configuration isn’t trivial – And a lot still depends on configuration • Can’t depend on the CDN to solve all your problems • Don’t exacerbate your problems!
- 5. Gzipping Images • Not a very good thing for performance – Extra bytes – Extra work for the browser • But was this the Surrogate’s fault?
- 6. More Examples • Bad caching headers – max-‐age, s-‐maxage have a lot of power! – stale-‐if-‐error and stale-‐while-‐revalidate are rad! • Bad TCP connection management at origin • Not Gzipping (actual, compressible content) for origin fetches
- 8. Lesson: Dynamic Content Is Really Interesting!
- 9. What Is Dynamic Content? • Stuff that’s not static! • With web traffic, generally the base HTML – Big deal because it’s blocking – And sometimes the largest object; longer download • Some AJAX • More…
- 11. Blocking
- 12. Classically, with dynamic content… Caching
- 17. We tried…
- 18. Dynamic Content Caching Problems • Serving stale pages – Lack of good invalidation framework • Visibility • Logging
- 19. CDNs and Dynamic Content • Generally, handling dynamic content has been a matter of transport – Middle mile optimizations – TCP tweaks • Some edge micro caching, but not easy • ESI
- 20. Actually… • Dynamic content is more cacheable than we think • Static for short periods of time • Unpredictable invalidation – Standard HTTP caching rules aren’t good enough • Event-‐driven Content
- 21. So Many Benefits! • Performance – Faster time to first byte – Faster start render – Happy users! • Offload – Less work for our servers – Less bandwidth at origin
- 22. What Would Make It Better? • Programmatic Invalidation – Granular – Instantaneous • Control at the edge, and not just for web pages – Real-‐time log files – Imagine terminating beacons at the edge!
- 23. Lesson: Measurement is Still Hard
- 24. Client-‐side Measurement in CDNs • Cache hit ratio – How do you test and measure? • Long tail content? • DNS and edge node selection • TTFB out of datacenter – Memory hit vs disk hit vs mid-‐tier hit vs miss • RUM and synthetic (Cedexis, Catchpoint, etc)
- 25. Let’s Test It! • 3 Objects on the same CDN (anonymous) – Cedexis object – Small image from Alexa 5000 site – Long tail object: ~40 times every 3-‐4 hours • Use Catchpoint last mile clients in US – Test every 15 minutes – ~11,500 total tests across all test nodes • Focus measurement on: – Connect time (TCP) – Wait time (TTFB)
- 26. Cedexis Object Connect (median) Wait (median) Cedexis 14ms 19ms
- 27. Cedexis Object Alexa 5000 Connect (median) Wait (median) Cedexis 14ms 19ms Alexa 5000 14ms 24ms
- 28. Cedexis Object Alexa 5000 Connect (median) Wait (median) Cedexis 14ms 19ms Alexa 5000 14ms 24ms 26%
- 29. Cedexis Object Long TailAlexa 5000 Connect (median) Wait (median) Cedexis 14ms 19ms Alexa 5000 14ms 24ms Long Tail 15ms 29ms
- 30. Cedexis Object Long TailAlexa 5000 Connect (median) Wait (median) Cedexis 14ms 19ms Alexa 5000 14ms 24ms Long Tail 15ms 29ms 20%
- 31. Cedexis Object Count TCP TTFB Count TCP TTFB Count TCP TTFB Mem 11,074 14ms 19ms 481 14ms 19ms 6741 14ms 20ms Disk 428 12ms 24ms 9626 15ms 28ms 4692 14ms 31ms Miss 1 6ms 38ms 1355 16ms 51ms 28 13ms 45ms
- 32. Cedexis Object Alexa 5000 Count TCP TTFB Count TCP TTFB Count TCP TTFB Mem 11,074 14ms 19ms 6741 14ms 20ms 481 14ms 19ms Disk 428 12ms 24ms 4692 14ms 31ms 9626 15ms 28ms Miss 1 6ms 38ms 28 13ms 45ms 1355 16ms 51ms
- 33. Cedexis Object Long TailAlexa 5000 Count TCP TTFB Count TCP TTFB Count TCP TTFB Mem 11,074 14ms 19ms 6741 14ms 20ms 481 14ms 19ms Disk 428 12ms 24ms 4692 14ms 31ms 9626 15ms 28ms Miss 1 6ms 38ms 28 13ms 45ms 1355 16ms 51ms
- 34. Cedexis Object Long TailAlexa 5000 Count TCP TTFB Count TCP TTFB Count TCP TTFB Mem 11,074 14ms 19ms 6741 14ms 20ms 481 14ms 19ms Disk 428 12ms 24ms 4692 14ms 31ms 9626 15ms 28ms Miss 1 6ms 38ms 28 13ms 45ms 1355 16ms 51ms 99.99% Mem: 96.27% Disk: 3.72%
- 35. Cedexis Object Long TailAlexa 5000 Count TCP TTFB Count TCP TTFB Count TCP TTFB Mem 11,074 14ms 19ms 6741 14ms 20ms 481 14ms 19ms Disk 428 12ms 24ms 4692 14ms 31ms 9626 15ms 28ms Miss 1 6ms 38ms 28 13ms 45ms 1355 16ms 51ms 99.99% Mem: 96.27% Disk: 3.72% 99.76% Mem: 58.82% Disk: 40.94%
- 36. Cedexis Object Long TailAlexa 5000 Count TCP TTFB Count TCP TTFB Count TCP TTFB Mem 11,074 14ms 19ms 6741 14ms 20ms 481 14ms 19ms Disk 428 12ms 24ms 4692 14ms 31ms 9626 15ms 28ms Miss 1 6ms 38ms 28 13ms 45ms 1355 16ms 51ms 99.99% Mem: 96.27% Disk: 3.72% 99.76% 88.17% Mem: 58.82% Disk: 40.94% Mem: 4.19% Disk: 83.98%
- 37. Measurement! • Not only do I care about: – Cache hit rate – Long tail – Measuring the right thing • Fetching from disk could suck! – SSDs! • Caching ≠ Caching
- 38. Lesson: CDNs Are Not Solved!
- 39. We Don’t Cache As Much As We Should! • HTML and other dynamic content • Worse cache hit rate than we think – Especially for long tail content • Mobile Apps, APIs, etc
- 40. Lots of Room • Making changes still sucks • Can’t take some things for granted: – DNS – Routing – TCP – SCALE! • Plus: lots of room to be creative at the edge!
- 41. Thank you!
- 42. Lesson: It’s Not Only About…
- 43. …Performance!!!
- 44. Security • Certificate management • Perimeter security • DDoS protection <-‐ benefit of scale!
- 45. Flexibility, Visibility, and Control • Integration • Programmability • APIs • Instant purging • Real time logs
- 46. Fun at the Edge! • Synthetic responses – Example: node ID for Cedexis measurements • Cookie manipulation – Remove/inject/replace/recall • Beacon termination – 204 responses – Real time logs – Awesome!
- 47. PERFORMANCE!! It’s still pretty damn important!
- 48. This is not a sales pitch!
- 49. Making Changes SUCKS!! • Configuration changes take way too long – People are used to making changes real-‐time – CDNs aren’t classically good at this – Phone?? • Purging is a real problem – Slow – Difficult – Not granular enough
- 50. Lesson: There’s More to the Web Than the Web!
- 51. Non “web” Traffic • Video – HLS (HTTP Live Streaming) – HTTP-‐based small video chunks – Unique by URL • APIs – Instant purging can let API calls be cacheable – Another example of dynamic content cached at the edge • Mobile Apps
- 53. The Influence of Clouds • DevOps people like programmability and integration • The CDN is no longer a black box mechanism, necessarily • Cliché Alert: Content as a Service!
- 54. Real Time Integration • Tap in to the CDN: – Instantaneous configuration changes – Instantaneous cache purge and invalidation – Real time stats and logs • Infrastructure as code – Expect extensive APIs – Apps need to naturally extend to the CDN – Your content => you need control
- 55. About Time!!
- 56. “Still” • In the world of FEO – Webpagetest.org – RUM – Synthetic testing vendors • In the world of CDNs – Same as far as client performance goes – Some new things…