Core Unleashed Part II: Introduction to GobiesVM (and STM) @ RubyKaigi 2014

http://blog.brucehsu.org/posts/2014/09/29/rubykaigi-2014-cores-unleashed-part-ii-introduction-to-gobiesvm-and-software-transactional-memory

Transcript

1. Cores Unleashed Part II
   Introducing GobiesVM (and STM)
   Szu-Kai Hsu (@brucehsu)
   

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2. Szu-Kai Hsu
   @brucehsu
   

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5. Previously on
   Cores Unleashed
   

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6. Concurrency/Parallelism
   in Ruby
   Concurrency Parallelism
   MRI/CRuby ✔ ✘
   Rubinius ✔ ✔
   JRuby ✔ ✔
   Topaz ✘ ✘
   

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7. CPU Usage
   

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8. CPU Usage - MRI
   

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9. CPU Usage - Rubinius
   

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10. CPU Usage - JRuby
    

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11. Thread Safety
    

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12. Thread Safety - MRI
    

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13. Thread Safety - Rubinius
    

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14. Thread Safety - JRuby
    

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15. Locks are bad
    “Beautiful Concurrency”, Simon Peyton Jones (2007)
    Taking too few locks
    Taking too many locks
    Taking the wrong locks
    Taking locks in the wrong order
    Error recovery
    Lost wake-ups and erroneous retries
    

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16. Software
    Transactional
    Memory
    

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17. GobiesVM
    https://github.com/brucehsu/GobiesVM
    

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18. GobiesVM in a nutshell
    Written in Go, utilizing native data structures and GC
    A Ruby subset derived from tinyrb
    Therefore uses a LEG parser instead of bison
    Stack-based VM which resembles YARV
    Minimal modification to existing code
    

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19. VM
    Coroutine Coroutine Coroutine Coroutine
    Bytecode
    Abstract Syntax Tree
    

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20. VM
    Coroutine Coroutine Coroutine Coroutine
    Transaction
    Transaction
    Transaction
    Transaction
    Transaction
    Transaction
    Transaction
    Transaction
    Transaction
    Transaction
    Transaction
    Transaction
    

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21. BC_GETLOCAL, i
    BC_SEND, +, 1
    BC_PUTOBJ, 1
    BC_SEND
    BC_GETLOCAL
    Begin
    End
    Transaction
    bytecode
    stack
    ivar
    object-set
    rev
    

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22. Transactional Locking II
    Global Timestamp
    Transaction Transaction
    Local Timestamp Local Timestamp
    Read Set Read Set
    Write Set
    Write Set
    Transaction
    Local Timestamp
    Read Set
    Write Set
    

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23. Speculative Execution
    (READ)
    a
    Read Set
    Write Set
    a
    b
    c
    d
    e
    0x5566
    0x5567
    0x5568
    0x5569
    0x5570
    0x5566
    10
    

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24. Speculative Execution
    (WRITE)
    a+=1
    Read Set
    Write Set
    a
    b
    c
    d
    e
    0x5566
    0x5567
    0x5568
    0x5569
    0x5570
    0x5566
    a 11
    10
    0x5566
    

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25. Speculative Execution
    (READ-AFTER-WRITE)
    a
    Read Set
    Write Set
    a
    b
    c
    d
    e
    0x5566
    0x5567
    0x5568
    0x5569
    0x5570
    0x5566
    a 11
    

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26. Combined Object-Set
    RObject
    Object-Set
    Read-Set
    

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27. Combined Object-Set
    RObject
    Object-Set
    RObject
    Write-Set
    

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28. Validation
    Read Set
    Write Set
    Global Timestamp
    Check rev of object
    rev > local_timestamp: object has been modified
    Acquire locks of objects to be modified
    Abort on failure
    Increments by one
    

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29. Commit
    RObject
    class
    ivar
    methods
    RObject
    class
    ivar
    methods
    Copy to original
    

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30. – Torvalds, Linus (2000-08-25)
    Talk is cheap.
    Show me the code
    

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31. Live Demo
    

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32. What’s next?
    

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33. Better parser
    Go provides goyacc for parsing
    But we have to do lexical scanning ourselves.
    https://sourcegraph.com/blog/multi-language-lexer-
    and-scanner-for-go
    

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34. Better syntax support
    What we don’t have now:
    Conditional statements
    Class/Method definitions
    Double-quoted strings
    And more…
    

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35. Atomic operations
    New syntax: atomic block
    Make every statement atomic
    

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36. Production-ready (perhaps)
    Rubygems
    Native extension interface
    Go can work with C code, but not thread-safe
    Comprehensive exceptions
    

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37. Optimizations
    Performance!
    Performance!!
    Transaction length
    

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38. GobiesVM
    https://github.com/brucehsu/GobiesVM
    

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39. Thanks for your attention
    Any questions?
    

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