1. cache
@TimYang

2. Agenda
• Feed
• Cache
•

3. •
• , status feed
•
•

4. Feed
• feed
• Push( )
• Pull( )
•

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

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
• followers list

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 /
• = 50 * 2k * 1,000 / sec = 100MB

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
• mutex

29. •
•
• less is more
•

30. •
• code review
•

31. • Q&A
• weihua2@staff.sina.com.cn