1. Simple Cache Architecture
charsyam@naver.com

2. What is Cache?

3. Cache == Speed

4. Disk Accessing
is too late

5. Operation Time
is too long

6. Client
Business
Object
Memory
Disk
ClientClientClient

7. Client
Business
Object
Distributed
Cache
DB
ClientClientClient

8. Connect via
Business Object

9. Don’t Connect
Client between
DB directly

10. Distributed
Cache

11. Consistent Hashing

12. Proxy
Server
Server
Server
Server
Server
User Request
K = 10000 N = 5
Origin

13. Proxy
Server
Server
Server
Server
Server
User Request
K = 10000 N = 4
FAIL : Redistribution about 2000 Users

14. Proxy
Server
Server
Server
Server
Server
User Request
K = 10000 N = 5
RECOVER: Redistribution about 2500 Users

15. A
Add A,B,C Server

16. A
B
Add A,B,C Server

17. A
B
C
Add A,B,C Server

18. A
B
C
1
Add Item 1

19. A
B
C
1
2
Add Item 2

20. A
B
C
1
2
3
4
5
Add Item 3,4,5

21. A
B
C
2
3
4
5
Fail!! B Server

22. A
B
C
1
2
3
4
5
Add Item 1 Again -> Allocated C Server

23. A
B
C
1
2
3
4
5
1
Recover B Server -> Add Item 1

24. A
B
C
Real Implementation
A+1
A+2
A+3B+1
B+2
C+1
C+2
A+4
C+3
B+3

25. Mistake

26. A
DB Cache
B
Normal Step
1. A:DB:W 2. A:Cache:W3. B:DB:W
4. B:Cache:W

27. A
DB Cache
B
Race Condition Step
1. A:DB:W 3. B:Cache:W2. B:DB:W
4. A:Cache:W

28. Solution?

29. Global Lock?

30. CAS?

31. Thank You!