The Path Towards Simplifying Consistency in Distributed Systems

Transcript

1. The Path Towards
   Simplifying
   Consistency in
   Distributed Systems
   

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

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3. Distributed Systems Engineer
   Feral Concurrency
   Control Programmer
   Caitie McCaffrey
   

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4. 2015
   

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

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

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7. Halo 4 Statistics Service
   

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8. Observability at Twitter
   Make Dashboards & Alerts
   Always Available
   

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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
   

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10. Notify Users When
    We Receive Abuse
    Reports
    

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11. Notify Users If An
    Action is Taken
    

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

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13. Feral Concurrency
    Control
    

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14. Service Service
    Service
    Monoliths
    

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15. The Rise of NoSQL
    

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17. Microservices
    

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18. State of Affairs
    

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

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26. Can We Do
    Better?
    

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27. Finance & Accounting
    

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28. VisiCalc
    1979
    

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29. 1983 Lotus 123
    

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31. 1987
    Excel
    

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33. &
    Standardization
    Computer Aided
    Computation
    

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34. Standardization
    for Consistency in Distributed Systems
    

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35. 1988
    

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

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

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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
    

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39. What about
    Spanner?
    

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40. 2015
    

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

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42. Microservices
    

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43. CRDTs
    * Stolen from Chris Meiklejohn
    in practice
    

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44. CRDTs
    * Stolen from Chris Meiklejohn
    in practice
    

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45. There Is No One
    Size Fits All
    Consistency Model
    

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46. Mixed Consistency Data Stores
    Manhattan
    

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48. Computer Aided
    Computation
    for Consistency in Distributed Systems
    

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49. 2016
    

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

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

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

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53. &
    Standardization
    Computer Aided
    Computation
    

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54. Thank you
    @caitie
    

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