Caching, why not?

Highload meetup: talks by Megogo, 2015

Transcript

1. Caching, why not? Highload Meetup: talks by Megogo
2. About me • Dmitriy Kovalenko @dkovalenko_fun • TeamLead @ x2sy: Megogo • Actively using: Scala, php • Also: Clojure, golang
3. About us • > 4 million users every day • > 30000 hours of video content • Web, iOS, Android, SmartTV, OTT Boxes • CIS, Baltics, Europe
4. Agenda • Caching across tiers: 1. Browser 2. Frontend server/proxy 3. Application • Cache infrastructure • Microservices and caching
5. Speedup your Application
8. • Cache-control • Max-Age, S-Max-Age (seconds) • Expires • ETag (If-None-Match) Headers
10. Use CDN, Carl! • Move your Images, JS, CSS -> CDN • Assets minifying, response gzipping
11. Use your Frontend/ Cacher/ Proxy
12. Reverse proxy • Varnish Cache • Nginx • Use your cache store directly (CouchDB, Memcached) • Split your page, think about SSI/ESI includes
14. frontend server caching pros: • High speed • Zero overhead for application • Usually can be applied without application change
15. frontend server caching cons: • Hard to debug • Hard to get right • Changes in application needs additional synchronization
16. Application cache pros: • Much controllable than frontend cache • Can use Application context • Swapping implementations in not a problem
17. Problems to think about • Key selection, Cache Tags • Invalidation schema • Cold start/full flush • Dogpile effect • Embedded or External • Local or Distibuted
18. <?php $data = $cache->get('some_key'); if ($data === false) { $data = getFromDB(); $cache->set($data); } return $data;
19. Cache slam problem
20. Eviction strategies • LRU • LFU • FIFO • Lifetime
21. Cache in cluster CP DB Service 2 WEB API Service 2
22. Going further with Microservices
23. There are only two hard things in Computer Science: cache invalidation and naming things. ! -- Phil Karlton
24. Solutions • Nodes list • Shared/Distributed caches • Master invalidates slaves • Queue • Cache cleaner • ETag FTW!
31. Great caching is like great sex. It hides all the real problems. ! @vivekhaldar Questions?