The document discusses caching strategies for social media feeds. It describes using different caches for hot, recent content (inbox cache), older content for followers (outbox vector), and archived historic content (archive cache). It also discusses caching social graphs like followers and following lists. The caches aim to optimize for fast retrieval of recent home timelines and individual user feeds. Mutexes are used to synchronize cache updates between servers.

1. cache
@TimYang

2. Agenda
• Feed
• Cache

3. •
• , status feed
•

4. Feed
• feed
• Push( )
• Pull( )
•

5. Push
• feed
• Inbox:
• Outbox:
• inbox( )
• Inbox( )

6. Push
•
•
•

7. Pull
• outbox( )
• Inbox( )
• Online computation

8. Pull
•
•

9. •
•
•

10. Cache
memory is the new disk,
and disk is the new tape.
for "real-time" web applications,
and systems that require massive scalability
- Jim Gray

11. Cache

12. cache
Weibo cache arch
Inbox hot cache
Outbox Vector cache Archive cache
Social Following Followers users
Graph
Content Hot cache Total

13. Inbox
• “ ”
• cache id list
• (hot cache)
• get set
• redis list/set

14. Outbox
•
• id list(e.g. 100)
• id LRU

15. Social Graph cache
• Following ids
• Followers
•
•
• delete all

16. Content cache
• cache
•
•
•
• Open API xml, json...

17. Cache
•
•

18. Update Workflow
Update status
Content cache Hot Inbox Vector Outbox vector
Content cache
replication

19. • outbox hot vector
• followers list
• inbox

20. feed
Home timeline Workflow
home_timeline
aggregator
Content hot
Inbox cache Outbox Vector
cache
Inbox archive Inbox archive Content cache

21. feed
• inbox cache
•
• , following
• id list feed

22. cache
•
• hot keys
•
• mutex

23. • Content cache
• multi get n feed(n = items/ , e.g. 50)
• cache = n * (feed + ,
e.g. 2k)
• 1,000 /

24. • 1,000 800Mbps
•1 8Gbps

25. • 1G 300~400Mbps
•
• local cache
•
•

26. hot keys
• content cache of
• create local cache
1. get user_yaochen_local
2. get user_yaochen
1. set user_yaochen_local:value
3. delete all

27. cache
• key
memcache
•
• LRU cache,
• Memory storage

28. mutex
• content item cache
• db
• db
• key_mutex key
• mutex

29. •
• S2
• S2
•

30. S2
• Web 2.0 Social
• What’s S2
• Social Platform &
• Social Applications
• www.s2forum.org

31. •
• Sina App Engine
•
•
•

32. Q&A
• email: iso1600@gmail.com
• @TimYang