The Path Towards Simplifying Consistency in Distributed Systems

Transcript

1. The Path Towards
   Simplifying
   Consistency in
   Distributed Systems
   

   View Slide

2. Caitie McCaffrey
   Distributed Systems Engineer
   caitiem.com
   @caitie
   

   View Slide

3. Distributed Systems Engineer
   Feral Concurrency
   Control Programmer
   Caitie McCaffrey
   

   View Slide

4. View Slide

5. 2015
   “Application-level
   Mechanisms for maintaining
   database integrity”
   

   View Slide

6. Halo 4 Statistics Service
   Halo 4 Statistics Service
   Record & Aggregate Statistics
   From Every Multiplayer Halo
   Game a User Plays
   

   View Slide

7. Halo 4 Statistics Service
   

   View Slide

8. Observability at Twitter
   Make Dashboards & Alerts
   Always Available
   

   View Slide

9. Cmd Line Tool Viz / Dashboad Alerting Svc
   Cuckoo-Read
   Cuckoo-Write
   Indexing Svc
   Relay Svc
   Twitter Front End
   Twitter
   Svc
   Twitter
   Statsite
   Twitter
   Svc
   Twitter
   Svc
   Scribe
   Collection
   Agent
   HDFS
   Manhattan Database
   Public Cloud
   Observability at Twitter
   

   View Slide

10. Notify Users When
    We Receive Abuse
    Reports
    

    View Slide

11. Notify Users If An
    Action is Taken
    

    View Slide

12. Report
    Events Stream
    Modification
    Events Stream
    Enrollment
    Events Stream
    Listener Service
    Daemons Service
    Executor Service
    Notification Events
    Stream
    Notification
    Service
    Manhattan
    Macaw
    

    View Slide

13. Feral Concurrency
    Control
    

    View Slide

14. Service Service
    Service
    Monoliths
    

    View Slide

15. The Rise of NoSQL
    

    View Slide

16. View Slide

17. Microservices
    

    View Slide

18. State of Affairs
    

    View Slide

19. Linearizable
    Sequential
    Causal
    Pipelined Random
    Access Memory
    Read Your
    Write
    Monotonic
    Read
    Monotonic
    Write
    Write From
    Read
    Consistency
    Models
    

    View Slide

20. View Slide

21. View Slide

22. View Slide

23. View Slide

24. View Slide

25. View Slide

26. Can We Do
    Better?
    

    View Slide

27. Finance & Accounting
    

    View Slide

28. VisiCalc
    1979
    

    View Slide

29. 1983 Lotus 123
    

    View Slide

30. View Slide

31. 1987
    Excel
    

    View Slide

32. View Slide

33. &
    Standardization
    Computer Aided
    Computation
    

    View Slide

34. Standardization
    for Consistency in Distributed Systems
    

    View Slide

35. View Slide

36. 1988
    “We believe the form of
    communication that is needed is
    remote procedure call with at-
    most-once semantics”
    

    View Slide

37. 1988
    “An adequate language must
    provide a modular, reasonably
    automatic method for achieving
    consistency ”
    

    View Slide

38. Branch B
    Account 789: $250
    Branch A
    Account 123 : $100
    Account 456: $50
    SubAction: Deposit (123, 50)
    Transfer Action
    SubAction: Withdraw(789, 50)
    Transfer
    Deposit Withdraw
    enter topaction
    coenter
    action
    branchA.Deposit(123, 50)
    action
    branchB.Withdraw(789, 50)
    end
    end
    

    View Slide

39. What about
    Spanner?
    

    View Slide

40. View Slide

41. 2015
    “The biggest barrier…is that
    consistency mechanisms must
    integrate across many
    stateful services”
    

    View Slide

42. Microservices
    

    View Slide

43. CRDTs
    * Stolen from Chris Meiklejohn
    in practice
    

    View Slide

44. CRDTs
    * Stolen from Chris Meiklejohn
    in practice
    

    View Slide

45. There Is No One
    Size Fits All
    Consistency Model
    

    View Slide

46. Mixed Consistency Data Stores
    Manhattan
    

    View Slide

47. View Slide

48. Computer Aided
    Computation
    for Consistency in Distributed Systems
    

    View Slide

49. View Slide

50. Bank Application
    Bank Account must be > 0
    Deposit Money
    Withdrawal Money
    

    View Slide

51. ‘Cause I’m Strong Enough: Reasoning About Consistency Choices in Distributed Systems
    

    View Slide

52. Define Invariants
    & Actions
    Deposit Money
    Withdrawal Money
    Determine
    Consistency
    Required
    Bank Account > 0
    Eventual Consistency
    Strong Consistency
    Code
    Generation?
    

    View Slide

53. &
    Standardization
    Computer Aided
    Computation
    

    View Slide

54. Thank you
    @caitie
    

    View Slide