Argus Papers We Love

Argus Papers We Love

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Caitie McCaffrey

January 20, 2017
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  1. Distributed Programming in Argus Barbara Liskov Papers We Love SF

    - January 2017
  2. Caitie McCaffrey @caitie Distributed Systems Engineer CaitieM.com

  3. 1988

  4. “Technological advances have made it cost effective to construct large

    systems from collections of computer connected via networks. To support such systems, there is a growing need for effective way to organize and maintain distributed programs” Guardians and Actions: Linguistic Support for Robust, Distributed Programs
  5. Atomicity RPC &

  6. Guardians and Actions: Linguistic Support for Robust, Distributed Programs “We

    believe that the most desirable form of communication is the paired send and reply” Remote Procedure Calls
  7. Guardians and Actions: Linguistic Support for Robust, Distributed Programs “We

    believe the form of communication that is needed is remote procedure call with at-most-once semantics” Remote Procedure Calls
  8. Argus RPC In

  9. “a special kind of abstract object whose purpose is to

    encapsulate a resource” Guardians Distributed Programming in Argus
  10. “it permits its resource to be accessed by means of

    special procedures, called handlers” Handlers Distributed Programming in Argus
  11. Argus Banking with

  12. Branch Guardian Open (a: account_number) Close (a: account_number) Deposit (a:

    account_number, amt: int) Withdraw (a: account_number, amt: int) Total() Handlers
  13. Branch A Branch B Account 123 : $100 Account 456:

    $50 Account 789: $250 Open (123) Deposit(123, 100) Open (456) Deposit(456, 50) Open (789) Deposit(789, 250)
  14. Atomicity RPC &

  15. “An adequate language must provide a modular, reasonably automatic method

    for achieving consistency ” Atomicity Distributed Programming in Argus
  16. Guardians and Actions: Linguistic Support for Robust, Distributed Programs “Our

    solution to the problem of maintaining consistent distributed data in the face of concurrent, potentially interfering activities, and in the face of system failures such as node crashes and network disruptions while these activities are running is to make activities atomic” Atomicity
  17. Argus Atomicity In

  18. Serializable Actions Total (abort or commit)

  19. Atomic Abstract Data Type Atomic Objects Argus Provides: atomic arrays,

    records, variants, characters, and integers
  20. Read Write Lock Locking Rules Multiple Readers are Allowed Readers

    Exclude Writers Writer Exclude other Writers & Readers
  21. Distributed Programing in Argus “Computation in Argus starts as a

    top action at some guardian. The computation spreads to other guardians by means of handler calls. Execution of a handler call may cause some objects at the handler’s guardian to be modified, and may in turn lead to further calls”
  22. Argus Banking with

  23. Branch A Branch B Account 123 : $100 Account 456:

    $50 Account 789: $250 Transfer( amt: int, from: account_number, to: account_number)
  24. 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
  25. 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
  26. Branch B Account 789: $250 Branch A Account 123 :

    $100 Account 456: $50 Deposit (123, 50) Transfer Action Withdraw(789, 50)
  27. Branch B Account 789: $250 Branch A Account 123 :

    $100 Account 456: $50 Deposit (123, 50) Transfer Action Withdraw(789, 50) Account 123 : $150 Account 789: $200 V1 V1
  28. Branch B Account 789: $250 Branch A Account 123 :

    $100 Account 456: $50 Deposit Success Transfer Action Withdraw Success Account 123 : $150 Account 789: $200 V1 V1
  29. Branch B Account 789: $250 Branch A Account 123 :

    $100 Account 456: $50 Transfer Action Account 123 : $150 Account 789: $200 V1 V1 Commit Top Level Action 2PC Transfer Deposit Withdraw
  30. Branch B Branch A Prepare Transfer Action Prepare Commit Top

    Level Action 2PC: Phase 1 V1 V1 Account 789: $250 Account 123 : $100 Account 456: $50 Account 123 : $150 Account 789: $200
  31. Branch B Branch A Prepare Success Transfer Action Prepare Success

    Commit Top Level Action 2PC: Phase 1 V1 V1 Account 789: $250 Account 123 : $100 Account 456: $50 Account 123 : $150 Account 789: $200
  32. Branch B Branch A Account 456: $50 Commit Transfer Action

    Commit Account 123 : $150 Account 789: $200 Commit Top Level Action 2PC : Phase 2
  33. Branch B Branch A Account 456: $50 Commit Success Transfer

    Action Commit Success Account 123 : $150 Account 789: $200 Commit Top Level Action 2PC : Complete
  34. Argus Banking with

  35. Branch B Account 789: $200 Branch A Account 123 :

    $150 Account 456: $50 SubAction: Deposit (123, 100) Transfer Action SubAction: Withdraw(456, 100) Transfer Deposit Withdraw
  36. Branch B Account 789: $200 Branch A Account 123 :

    $150 Account 456: $50 Deposit (123, 100) Transfer Action Withdraw(456, 100)
  37. Branch B Account 789: $200 Branch A Account 123 :

    $150 Account 456: $50 Deposit Success Transfer Action Withdraw Abort V1 Account 123 : $250 Transfer Deposit Withdraw
  38. Branch B Account 789: $200 Branch A Account 123 :

    $150 Account 456: $50 Abort Deposit Transfer Action V1 Account 123 : $250 Abort Top Level Action 2PC : Abort
  39. Branch B Account 789: $200 Branch A Account 123 :

    $150 Account 456: $50 Deposit Aborted Transfer Action Abort Top Level Action 2PC : Abort
  40. Branch B Account 789: $200 Branch A Account 123 :

    $150 Account 456: $50 Transfer Action
  41. Sub-Actions “Argus allows actions to be nested; thus an action

    can have one or more sub-actions“ Distributed Programming in Argus Transfer Deposit Withdraw
  42. Sub-Actions Replicate Action Replica A Replica B

  43. Sub-Actions Replicate Deposit Replica A Replica B Transfer Deposit Withdraw

    Replicate Withdraw Replica A Replica B
  44. Sub-Actions Replicate Deposit Replica A Replica B Transfer Deposit Withdraw

    Replicate Withdraw Replica A Replica B
  45. Sub-Actions Replicate Deposit Replica A Replica B Transfer Deposit Withdraw

    Replicate Withdraw Replica A Replica B
  46. Sub-Actions Replicate Deposit Replica A Replica B Transfer Deposit Withdraw

    Replicate Withdraw Replica A Replica B Abort
  47. Sub-Actions Replicate Deposit Replica A Replica B Transfer Deposit Withdraw

    Replicate Withdraw Replica A Replica B
  48. Sub-Actions Replicate Deposit Replica A Replica B Transfer Deposit Withdraw

    Replicate Withdraw Replica A Replica B
  49. Sub-Actions Replicate Deposit Replica A Replica B Transfer Deposit Withdraw

    Replicate Withdraw Replica A Replica B 2PC: Abort
  50. Sub-Actions “Argus runs every handler call as a sub-action…this extra

    action ensures that calls have a zero or one semantics.“ Distributed Programming in Argus
  51. What if Sub-Actions try to access the same atomic object?

  52. What if Sub-Actions try to access the same atomic object?

  53. Read Lock: All holders of write locks on x must

    be ancestors of S Write Lock: All holders of write locks on x must be ancestors of S. Locking Rules for Sub-Actions Distributed Programming in Argus
  54. Commit: S’s parent acquires S’s lock on x. If S

    holds a write lock on x, then S’s version becomes S’s parent version Abort: S’s lock and version (if any) are discarded Version Management Rules for Sub Actions Distributed Programming in Argus
  55. Sub Action Locking Account Balance Object $200 Value X Y

    Z 1.5% Interest 2% Interest Read Balance
  56. Account Balance Object $200 V1 $203 Value X Y Z

    1.5% Interest 2% Interest Read Balance X: Write Lock (V1) Sub Action Locking
  57. Account Balance Object $200 V1 $203 V2 $207.06 Value X

    Y Z 1.5% Interest 2% Interest Read Balance X: Write Lock (V1) Y: Write Lock (V2) Sub Action Locking
  58. Account Balance Object $200 V1 $203 V2 $207.06 Value X

    Y Z W 1.5% Interest 2% Interest Read Balance .5% Interest X: Write Lock (V1) Y: Write Lock (V2) Z: Read Lock (V2) Sub Action Locking
  59. Account Balance Object $200 V1 $203 V2 V3 $207.06 $208.10

    Value X Y Z W 1.5% Interest 2% Interest Read Balance .5% Interest X: Write Lock (V1) Y: Write Lock (V2) Z: Read Lock (V2) W: Write Lock (V3) Sub Action Locking
  60. Account Balance Object $200 V1 $203 X: Write Lock (V1)

    V2 V3 $207.06 $208.10 Value Y: Write Lock (V2) Z: Write Lock (V3) X Y Z W 1.5% Interest 2% Interest Read Balance .5% Interest Sub Action Locking
  61. Account Balance Object $200 V1 $203 X: Write Lock (V1)

    V2 V3 $207.06 $208.10 Value Y: Write Lock (V3) X Y Z W 1.5% Interest 2% Interest Read Balance .5% Interest Sub Action Locking
  62. Account Balance Object $200 V1 $203 X: Write Lock (V3)

    V2 V3 $207.06 $208.10 Value X Y Z W 1.5% Interest 2% Interest Read Balance .5% Interest Sub Action Locking
  63. Account Balance Object $200 V1 $203 X: Write Lock (V3)

    V2 V3 $207.06 $208.10 Value Y: Write Lock (V3) Z: Write Lock (V3) X Y Z W 1.5% Interest 2% Interest Read Balance .5% Interest Sub Action Locking Two Phase Commit
  64. Account Balance Object $208.10 Value X Y Z W 1.5%

    Interest 2% Interest Read Balance .5% Interest Sub Action Locking
  65. Problems with Argus

  66. “The concurrency that is built in to the mail system

    can lead to a number of deadlock situations” Guardians and Actions: Linguistic Support for Robust, Distributed Programs “As implemented most of the handlers can deadlock with other concurrent operations” Distributed Programming in Argus Deadlocks
  67. Deadlocks “The programmer must think about deadlocks and starvation and

    implement the code to avoid them when possible" Distributed Programming in Argus
  68. Blocking Calls “A new process is created to perform an

    incoming handler call …[so guardians can] have the ability to execute many request concurrently … if the guardian is running on a single-processor node, then only one process will be running at a time” Guardians and Actions: Linguistic Support for Robust, Distributed Programs
  69. Blocking Calls “A new process is created to perform an

    incoming handler call …[so guardians can] have the ability to execute many request concurrently … if the guardian is running on a single-processor node, then only one process will be running at a time” Guardians and Actions: Linguistic Support for Robust, Distributed Programs Promises: linguistic support for efficient asynchronous procedure calls in distributed systems B. Liskov, L.Shrira 1988
  70. So where do we go from here?

  71. “Guardians allow programs to be decomposed into units of tightly

    coupled data and processing” Distributed Programming in Argus Guardians
  72. Microservices

  73. “Atomic actions are an important tool both for understanding what

    a system should do and for implementing it correctly” Distributed Programming in Argus
  74. 2014

  75. Halo 4: Statistics Service

  76. 2015

  77. 2015 “We focus our study on the common use of

    feral or a pplication-level, mechanisms for maintaining database integrity”
  78. 2015

  79. CRDT * Stolen from Chris Meiklejohn in practice

  80. 2012

  81. 2012 “ Spanner is the first system to distribute data

    at global scale and support externally-consistent distributed transaction”
  82. 2016

  83. None
  84. Conclusion

  85. Thank You! @caitie