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1. cache
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2. Agenda
• Feed
• Cache
•
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3. •
• , status feed
•
•
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4. Feed
• feed
• Push( )
• Pull( )
•
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5. Push
• feed
• Inbox:
• Outbox:
• inbox( )
• Inbox( )
• Offline computation
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6. Push
•
•
•
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7. Pull
• outbox( )
• Inbox( )
• Online computation
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8. Pull
•
•
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9. •
•
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10. Pull cache arch
Inbox Page cache
Outbox Vector cache Archive data
Social Following Followers users
Graph
Content Hot cache Total
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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
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13. terminology
• content cache:
• vector cache: feed id list
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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
•
•
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18. 2.
• gzip
• quicklz
• lzo
• , zhangwei
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19. 3.
•1 100
• 100 memcache 10
• memcache udp
• Throughput/Latency/connections
• todo: , zhangwei
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20. 4.
• key
memcache
•
• LRU cache,
• Memory storage
•
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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
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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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