1. cache
1

2. Agenda
• Feed
• Cache
•
2

3. •
• , status feed
•
•
3

4. Feed
• feed
• Push( )
• Pull( )
•
4

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

6. Push
•
•
•
6

7. Pull
• outbox( )
• Inbox( )
• Online computation
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8. Pull
•
•
8

9. •
•
9

10. Pull cache arch
Inbox Page cache
Outbox Vector cache Archive data
Social Following Followers users
Graph
Content Hot cache Total
10

11. 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
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12. Memcache
12

13. terminology
• content cache:
• vector cache: feed id list
13

14. content cache
• multi get n (n = items/page, e.g. 50)
• size = n * length of feed + header (e.g. 2k)
• concurrent requests / sec, e.g. 1,000
• total = 50 * 2k * 1000 / sec
• total = 100M * 8bit = 800Mbps
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15. 15

16. 1.
• 1,000 800Mbps
•1 8Gbps
• facebook Memcache: 60GB ~ 120GB/s
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17. 1.
• 1G 300~400Mbps
• local cache
•
•
17

18. 2.
• gzip
• quicklz
• lzo
• , zhangwei
18

19. 3.
•1 100
• 100 memcache 10
• memcache udp
• Throughput/Latency/connections
• todo: , zhangwei
19

20. 4.
• key
memcache
•
• LRU cache,
• Memory storage
•
20

21. 5. 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
21

22. 6. mutex
• content item cache
• db
• db
• key_mutex key
• mutex
• mutex
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23. 6. mutex
• 2: cache
•
•
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24. 7. value list
• vector cache, 100
• {1,2,3,4...98,99.100}
•
• append/prepend
• get set
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25. 8. memcache proxy
• proxy
• pros
• cons
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