Let's Talk about PyPy

Invited Keynote at PyCon 2012. Santa Clara. Conference video at https://www.youtube.com/watch?v=l_HBRhcgeuQ

Transcript

1. Let's Talk About
   David Beazley
   @dabeaz
   

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2. PyPy Project
   • Perhaps you've heard about PyPy
   • Python implemented in Python
   • It is apparently quite a bit faster
   • How is that possible? Magic???
   

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3. It's Not Slow
   Draw the Mandelbrot set
   Credit: Jeff Preshing
   CPython 2.7: 502s
   _ = (
   255,
   lambda
   V ,B,c
   :c and Y(V*V+B,B, c
   -1)if(abs(V)<6)else
   ( 2+c-4*abs(V)**-0.4)/i
   ) ;v, x=1500,1000;C=range(v*x
   );import struct;P=struct.pack;M,\
   j ='for X in j('BM'+P(M,v*x*3+26,26,12,v,x,1,24))or C:
   i ,Y=_;j(P('BBB',*(lambda T:(T*80+T**9
   *i-950*T **99,T*70-880*T**18+701*
   T **9 ,T*i**(1-T**45*2)))(sum(
   [ Y(0,(A%3/3.+X%v+(X/v+
   A/3/3.-x/2)/1j)*2.5
   /x -2.7,i)**2 for \
   A in C
   [:9]])
   /9)
   ) )
   

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4. It's Not Slow
   Draw the Mandelbrot set
   Credit: Jeff Preshing
   CPython 2.7: 502s
   _ = (
   255,
   lambda
   V ,B,c
   :c and Y(V*V+B,B, c
   -1)if(abs(V)<6)else
   ( 2+c-4*abs(V)**-0.4)/i
   ) ;v, x=1500,1000;C=range(v*x
   );import struct;P=struct.pack;M,\
   j ='for X in j('BM'+P(M,v*x*3+26,26,12,v,x,1,24))or C:
   i ,Y=_;j(P('BBB',*(lambda T:(T*80+T**9
   *i-950*T **99,T*70-880*T**18+701*
   T **9 ,T*i**(1-T**45*2)))(sum(
   [ Y(0,(A%3/3.+X%v+(X/v+
   A/3/3.-x/2)/1j)*2.5
   /x -2.7,i)**2 for \
   A in C
   [:9]])
   /9)
   ) )
   PyPy-1.8: 203s
   Speedup of ~2.5x
   

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5. It's Not Slow
   Draw the Mandelbrot set (non-obfuscated)
   Python 2.7.2 : 14.5s
   Python 2.7.2+ctypes : 0.95s
   PyPy-1.8 : 0.42s
   Yow! That's 34x faster!
   

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6. I LIKE IT!
   "Laziness is the first great virtue of a programmer"
   -- Larry Wall
   

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7. CPython PyPy
   One is clearly faster than the other...
   

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8. CPython PyPy
   Just in time compilation
   Translation to C
   Optimization
   One is clearly faster than the other...
   

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9. CPython PyPy
   Just in time compilation
   Translation to C
   Optimization
   ... but performance is not what this talk is about.
   One is clearly faster than the other...
   

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10. CPython PyPy
    • Which one can you adjust with a pocketknife?
    

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11. CPython PyPy
    • Which one can you adjust with a pocketknife?
    ... in the dark
    

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12. CPython PyPy
    • Which one can you adjust with a pocketknife?
    ... in the dark
    ... under a pressing deadline
    

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13. CPython PyPy
    • Which one can you adjust with a pocketknife?
    ... in the dark
    ... under a pressing deadline
    I speak from some experience...
    

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14. View Slide

15. Thinking about Tinkering
    (with PyPy)
    

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16. Tinkering Matters!
    CPython
    

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17. Tinkering Matters!
    CPython
    Patches
    

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18. Tinkering Matters!
    CPython
    Patches
    PEPs
    

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19. Tinkering Matters!
    CPython
    Patches
    PEPs Extensions
    python-ideas
    

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20. "Oh, Interesting..."
    

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21. Exploring New Ideas
    ported to
    An "afternoon hack," with a big impact
    parallel Python
    

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22. Exploring New Ideas
    ported to
    An "afternoon hack," with a big impact
    parallel Python
    ... we didn't choose Python for performance.
    

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23. Tinkering Creates Cool Stuff
    

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24. CPython PyPy
    An honest question
    • Is PyPy something that YOU can tinker with?
    • As in YOU... sitting in this room.
    • Or is it for "evil genuises only?"
    

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25. Armin
    Maciej
    Alex
    You?
    

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26. A Confession
    • PyPy scares me
    • It's fast. I get that.
    • A lot of moving parts
    • A lot of advanced computer science inside
    

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27. Tinker Away!
    I Worry About Complexity ...
    Abandon all hope
    

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28. CPython PyPy
    An honest question
    • Is PyPy something that YOU can tinker with?
    Honest answer: I don't know
    

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29. • See if I could teach myself to tinker with PyPy
    • From scratch (I'm not a PyPy developer)
    • Use nothing but the source, online docs, etc.
    An Experiment:
    

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30. Constraints
    A part-time project
    

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31. Tinkering with PyPy != Using PyPy
    • If you want to use it, just run it
    • It's Python.
    • Not so interesting (not as much as tinkering)
    bash % pypy gofaster.py
    

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32. Tinkering with PyPy != Creating PyPy
    • submit a useful bug report (or patch)
    • Make extensions
    • Study parts of the implementation (GIL, etc.)
    • Post messages on pypy-ideas@pypy.org
    

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33. Where To Start?
    • Tinkerers use source
    • You build it yourself!
    • You read instructions
    http://pypy.org
    Go Download it. Now!
    

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34. Running py.py
    • PyPy is written in "Python"... you can run it
    bash % python pypy-1.8/pypy/bin/py.py
    [platform:execute] gcc-4.0 -c -arch x86_64 -O
    frame-pointer - \
    ...
    PyPy 1.8.0 in StdObjSpace on top of Python 2.
    (startuptime: 23.23 secs)
    >>>>
    • Performance is terrible!
    • You wouldn't do it except for debugging
    

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35. Translating PyPy
    • To get the "real" version, you translate it
    • Huh? No makefile? No setup.py?
    • Already, I'm getting nervous.
    bash % cd pypy/translator/goal
    bash % python translate.py -Ojit
    

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36. Demo
    

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37. Building PyPy
    Some Facts:
    • Movie is @ 64x speed
    • Takes a few hours
    Contrast: Configure and build CPython-3.2.2
    • ./configure; make -j8
    • Takes about 90 seconds
    Immediate Problem:
    • Finding enough RAM
    • It takes >4GB
    4 cores, 8 GB RAM EC2, m2.xlarge (17GB)
    What's Actually Happening
    • Translation of PyPy to C
    • Creates ~800 C files
    • ~10.4 million lines!
    • 350 Mbytes
    It might kill the C compiler (or your machine)
    • Example: gcc-4.2
    This is Amazing!
    • Dare I say "diabolical"
    • If not intimidating
    One of the most daunting parts of PyPy
    • Must redo the process if you make any tweak
    • An obvious barrier to casual tinkering
    

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38. RPython
    • PyPy is actually implemented in "RPython"
    • RPython is not an "interpreter", but a
    restricted subset of the Python language
    Python
    rpython
    • It can run as valid Python code, but that's
    about the only similarity
    

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39. RPython
    • Formal specification (in their own words):
    "RPython is everything that our translation
    toolchain can accept"
    

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40. RPython
    • Formal specification (in their own words):
    "RPython is everything that our translation
    toolchain can accept"
    • An analogy
    "Python is everything that runs without
    generating a traceback."
    

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41. RPython
    • Formal specification (in their own words):
    "RPython is everything that our translation
    toolchain can accept"
    • An analogy
    "Python is everything that runs without
    generating a traceback."
    • Okay, let's go reading...
    

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42. Documentation
    

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43. High-level Docs
    

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44. Detailed Tech Reports
    

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45. Detailed Tech Reports
    To be fair, it was a funded
    academic project in PL.
    (They had to write like this)
    

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46. Source Code
    • 454 directories
    • 5534 files (4513 .py source files)
    • ~1.25 million non-blank source lines (.py)
    By The Numbers:
    It's not so easy to just jump in and make sense of it
    

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47. Reading Blogs
    • Recommend start: Andrew Brown
    • Laurence Tratt
    "Fast Enough VMs in Fast Enough Time"
    "Tutorial: Writing an Interpreter with PyPy"
    http://bit.ly/fmV2wx
    http://bit.ly/y8GLqf
    

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48. Just Do It
    (Live RPython Coding Demo)
    

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49. RPython in a Nutshell
    • RPython is a completely different language
    • Python syntax, yes.
    • Must be compiled (like C, C++, etc.)
    • Static typing via type inference
    • Limited set of libraries
    • If you love Python, you will hate RPython
    

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50. Type Inference Illustrated
    def fib(n):
    if n < 2:
    return n
    else:
    return fib(n-1) + fib(n-2)
    def main(argv):
    print fib(int(argv[1]))
    return 0
    

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51. Type Inference Illustrated
    def fib(n):
    if n < 2:
    return n
    else:
    return fib(n-1) + fib(n-2)
    def main(argv):
    print fib(int(argv[1]))
    return 0
    int
    

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52. Type Inference Illustrated
    def fib(n):
    if n < 2:
    return n
    else:
    return fib(n-1) + fib(n-2)
    def main(argv):
    print fib(int(argv[1]))
    return 0
    int
    int
    

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53. Type Inference Illustrated
    def fib(n):
    if n < 2:
    return n
    else:
    return fib(n-1) + fib(n-2)
    def main(argv):
    print fib(int(argv[1]))
    return 0
    int
    int
    int
    

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54. Type Inference Illustrated
    def fib(n):
    if n < 2:
    return n
    else:
    return fib(n-1) + fib(n-2)
    def main(argv):
    print fib(int(argv[1]))
    return 0
    int
    int
    int
    int
    

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55. Type Inference Illustrated
    def fib(n):
    if n < 2:
    return n
    else:
    return fib(n-1) + fib(n-2)
    def main(argv):
    print fib(int(argv[1]))
    return 0
    int
    int
    int
    int
    int
    Key Point: Think static typing (like C)
    

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56. # file1.py
    def name2(args):
    statement
    statement
    def name3(args):
    statement
    statement
    statement
    statement
    def name1(args):
    statement
    statement
    statement
    # file2.py
    def name1(args):
    statement
    statement
    statement
    class B(object):
    def method1(self,args):
    statement
    statement
    statement
    def method2(self,args):
    statement
    statement
    PyPy
    Source
    def name1(args):
    statement
    statement
    # file3.py
    def name2(args):
    statement
    statement
    def name3(args):
    statement
    statement
    def name4(args):
    statement
    statement
    Now think about the
    whole program
    Type inference +
    restrictions
    

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57. # file1.py
    def name2(args):
    statement
    statement
    def name3(args):
    statement
    statement
    statement
    statement
    def name1(args):
    statement
    statement
    statement
    # file2.py
    def name1(args):
    statement
    statement
    statement
    class B(object):
    def method1(self,args):
    statement
    statement
    statement
    def method2(self,args):
    statement
    statement
    PyPy
    Source
    def name1(args):
    statement
    statement
    # file3.py
    def name2(args):
    statement
    statement
    def name3(args):
    statement
    statement
    def name4(args):
    statement
    statement
    There is a single spark...
    Entry point
    

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58. # file1.py
    def name2(args):
    statement
    statement
    def name3(args):
    statement
    statement
    statement
    statement
    def name1(args):
    statement
    statement
    statement
    # file2.py
    def name1(args):
    statement
    statement
    statement
    class B(object):
    def method1(self,args):
    statement
    statement
    statement
    def method2(self,args):
    statement
    statement
    PyPy
    Source
    def name1(args):
    statement
    statement
    # file3.py
    def name2(args):
    statement
    statement
    def name3(args):
    statement
    statement
    def name4(args):
    statement
    statement
    Entry point
    Exploration Begins
    

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59. # file1.py
    def name2(args):
    statement
    statement
    def name3(args):
    statement
    statement
    statement
    statement
    def name1(args):
    statement
    statement
    statement
    # file2.py
    def name1(args):
    statement
    statement
    statement
    class B(object):
    def method1(self,args):
    statement
    statement
    statement
    def method2(self,args):
    statement
    statement
    PyPy
    Source
    def name1(args):
    statement
    statement
    # file3.py
    def name2(args):
    statement
    statement
    def name3(args):
    statement
    statement
    def name4(args):
    statement
    statement
    Exploration Begins
    Entry point
    

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60. # file1.py
    def name2(args):
    statement
    statement
    def name3(args):
    statement
    statement
    statement
    statement
    def name1(args):
    statement
    statement
    statement
    # file2.py
    def name1(args):
    statement
    statement
    statement
    class B(object):
    def method1(self,args):
    statement
    statement
    statement
    def method2(self,args):
    statement
    statement
    PyPy
    Source
    def name1(args):
    statement
    statement
    # file3.py
    def name2(args):
    statement
    statement
    def name3(args):
    statement
    statement
    def name4(args):
    statement
    statement
    Entry point
    Exploration Begins
    Whole program
    type annotation!
    

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61. # file1.py
    def name2(args):
    statement
    statement
    def name3(args):
    statement
    statement
    statement
    statement
    def name1(args):
    statement
    statement
    statement
    # file2.py
    def name1(args):
    statement
    statement
    statement
    class B(object):
    def method1(self,args):
    statement
    statement
    statement
    def method2(self,args):
    statement
    statement
    PyPy
    Source
    def name1(args):
    statement
    statement
    # file3.py
    def name2(args):
    statement
    statement
    def name3(args):
    statement
    statement
    def name4(args):
    statement
    statement
    All reachable control-
    flow paths are followed
    Entry point
    Whole program
    type annotation!
    

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62. # file1.py
    def name2(args):
    statement
    statement
    def name3(args):
    statement
    statement
    statement
    statement
    def name1(args):
    statement
    statement
    statement
    # file2.py
    def name1(args):
    statement
    statement
    statement
    class B(object):
    def method1(self,args):
    statement
    statement
    statement
    def method2(self,args):
    statement
    statement
    PyPy
    Source
    def name1(args):
    statement
    statement
    # file3.py
    def name2(args):
    statement
    statement
    def name3(args):
    statement
    statement
    def name4(args):
    statement
    statement
    Entry point
    Imagine this diagram,
    but with tens of
    thousands of functions
    Whole program
    type annotation!
    

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63. # file1.py
    def name2(args):
    statement
    statement
    def name3(args):
    statement
    statement
    statement
    statement
    def name1(args):
    statement
    statement
    statement
    # file2.py
    def name1(args):
    statement
    statement
    statement
    class B(object):
    def method1(self,args):
    statement
    statement
    statement
    def method2(self,args):
    statement
    statement
    PyPy
    Source
    def name1(args):
    statement
    statement
    # file3.py
    def name2(args):
    statement
    statement
    def name3(args):
    statement
    statement
    def name4(args):
    statement
    statement
    Key Insight:
    Entry point
    All of the reachable
    code is RPython
    

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64. RPython
    def name1(args):
    statement
    statement
    statement
    # file1.py
    def name2(args):
    statement
    statement
    def name3(args):
    statement
    statement
    statement
    statement
    def name1(args):
    statement
    statement
    statement
    def name3(args):
    statement
    statement
    statement
    statement
    # file2.py
    def name1(args):
    statement
    statement
    statement
    class B(object):
    def method1(self,args):
    statement
    statement
    statement
    def method2(self,args):
    statement
    statement
    PyPy
    Source
    def name1(args):
    statement
    statement
    # file3.py
    def name2(args):
    statement
    statement
    def name3(args):
    statement
    statement
    def name4(args):
    statement
    statement
    class B(object):
    def method1(self,args):
    statement
    statement
    statement
    def method2(self,args):
    statement
    statement
    def name1(args):
    statement
    statement
    def name2(args):
    statement
    statement
    def name4(args):
    statement
    statement
    Translation
    C
    Compile
    pypy-c
    Entry point
    

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65. View Slide

66. Understanding Translation
    • The translation process will blow your mind
    • Full understanding by mortals is probably futile
    • Snakes + Souls of Ph.D. students inside?
    • Let's look at a small taste...
    

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67. A Function
    def fib(n):
    if n < 2:
    return n
    else:
    return fib(n-1) + fib(n-2)
    Obvious question: How does it translate to C?
    

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68. Traditional Compiler
    def fib(n):
    if n < 2:
    return n
    else:
    return fib(n-1) + fib(n-2)
    Lexer Parser IR C
    You might think it's like a traditional compiler.
    

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69. Traditional Compiler
    def fib(n):
    if n < 2:
    return n
    else:
    return fib(n-1) + fib(n-2)
    Lexer Parser IR C
    You might think it's like a traditional compiler.
    (and you would be wrong)
    

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70. Traditional Compiler
    IR
    def fib(n):
    if n < 2:
    return n
    else:
    return fib(n-1) + fib(n-2)
    Lexer Parser C
    Insight: Python already parsed the code!
    ... so don't do it again.
    ?????
    

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71. RPython Translation
    IR C
    Translation occurs directly from Python code objects
    >>> fib.__code__.co_code
    '|\x00\x00d\x01\x00k\x00\x00r\x10\x00
    d\x02\x00St\x00\x00|\x00\x00d\x02\x00
    \x18\x83\x01\x00t\x00\x00|\x00\x00d
    \x01\x00\x18\x83\x01\x00\x17Sd\x00\x00S'
    

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72. Bytecode Interpretation
    CPython
    • Python has a bytecode interpreter
    • Core of the eval loop (written in C).
    bytecode
    interpreter
    runtime
    

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73. Bytecode Interpretation
    CPython
    • It executes the bytecode
    bytecode
    interpreter
    runtime
    >>> fib.__code__.co_code
    '|\x00\x00d\x01\x00k\x00\x00r\x1
    d\x02\x00St\x00\x00|\x00\x00d\x
    \x18\x83\x01\x00t\x00\x00|\x00\
    \x01\x00\x18\x83\x01\x00\x17Sd\
    

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74. Bytecode Interpretation
    PyPy
    • PyPy has a bytecode interpreter too
    • Written in pure Python (that's the whole idea)
    bytecode
    interpreter
    runtime
    >>> fib.__code__.co_code
    '|\x00\x00d\x01\x00k\x00\x00r\x1
    d\x02\x00St\x00\x00|\x00\x00d\x
    \x18\x83\x01\x00t\x00\x00|\x00\
    \x01\x00\x18\x83\x01\x00\x17Sd\
    

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75. Bytecode Interpretation
    PyPy
    runtime
    bytecode
    interpreter
    • Bytecode interpreter is modular
    • Also used by the translate.py program
    translate.py
    bytecode
    interpreter
    abstract runtime
    

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76. Just to be clear...
    PyPy translates itself using its
    own bytecode interpreter
    

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77. Abstract Interpretation
    translate.py
    bytecode
    interpreter
    abstract runtime
    2 0 LOAD_FAST 0 (n)
    3 LOAD_CONST 1 (2)
    6 COMPARE_OP 0 (<)
    9 POP_JUMP_IF_FALSE 16
    3 12 LOAD_CONST 2 (1)
    15 RETURN_VALUE
    5 >> 16 LOAD_GLOBAL 0 (fib)
    19 LOAD_FAST 0 (n)
    22 LOAD_CONST 2 (1)
    25 BINARY_SUBTRACT
    26 CALL_FUNCTION 1
    29 LOAD_GLOBAL 0 (fib)
    32 LOAD_FAST 0 (n)
    35 LOAD_CONST 1 (2)
    38 BINARY_SUBTRACT
    39 CALL_FUNCTION 1
    42 BINARY_ADD
    43 RETURN_VALUE
    44 LOAD_CONST 0 (None)
    47 RETURN_VALUE
    Translator runs the
    code "in the abstract"
    

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78. Abstract Interpretation
    Translator runs the
    code "in the abstract"
    2 0 LOAD_FAST 0 (n)
    3 LOAD_CONST 1 (2)
    6 COMPARE_OP 0 (<)
    9 POP_JUMP_IF_FALSE 16
    3 12 LOAD_CONST 2 (1)
    15 RETURN_VALUE
    5 >> 16 LOAD_GLOBAL 0 (fib)
    19 LOAD_FAST 0 (n)
    22 LOAD_CONST 2 (1)
    25 BINARY_SUBTRACT
    26 CALL_FUNCTION 1
    29 LOAD_GLOBAL 0 (fib)
    32 LOAD_FAST 0 (n)
    35 LOAD_CONST 1 (2)
    38 BINARY_SUBTRACT
    39 CALL_FUNCTION 1
    42 BINARY_ADD
    43 RETURN_VALUE
    44 LOAD_CONST 0 (None)
    47 RETURN_VALUE
    2 0 LOAD_FAST 0 (n)
    3 LOAD_CONST 1 (2)
    6 COMPARE_OP 0 (<)
    9 POP_JUMP_IF_FALSE 16
    3 12 LOAD_CONST 2 (1)
    15 RETURN_VALUE
    5 >> 16 LOAD_GLOBAL 0 (fib)
    19 LOAD_FAST 0 (n)
    22 LOAD_CONST 2 (1)
    25 BINARY_SUBTRACT
    26 CALL_FUNCTION 1
    29 LOAD_GLOBAL 0 (fib)
    32 LOAD_FAST 0 (n)
    35 LOAD_CONST 1 (2)
    38 BINARY_SUBTRACT
    39 CALL_FUNCTION 1
    42 BINARY_ADD
    43 RETURN_VALUE
    44 LOAD_CONST 0 (None)
    47 RETURN_VALUE
    Translator runs the
    code "in the abstract"
    translate.py
    bytecode
    interpreter
    abstract runtime
    

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79. Abstract Interpretation
    Translator runs the
    code "in the abstract"
    2 0 LOAD_FAST 0 (n)
    3 LOAD_CONST 1 (2)
    6 COMPARE_OP 0 (<)
    9 POP_JUMP_IF_FALSE 16
    3 12 LOAD_CONST 2 (1)
    15 RETURN_VALUE
    5 >> 16 LOAD_GLOBAL 0 (fib)
    19 LOAD_FAST 0 (n)
    22 LOAD_CONST 2 (1)
    25 BINARY_SUBTRACT
    26 CALL_FUNCTION 1
    29 LOAD_GLOBAL 0 (fib)
    32 LOAD_FAST 0 (n)
    35 LOAD_CONST 1 (2)
    38 BINARY_SUBTRACT
    39 CALL_FUNCTION 1
    42 BINARY_ADD
    43 RETURN_VALUE
    44 LOAD_CONST 0 (None)
    47 RETURN_VALUE
    translate.py
    bytecode
    interpreter
    abstract runtime
    

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80. Abstract Interpretation
    Translator runs the
    code "in the abstract"
    2 0 LOAD_FAST 0 (n)
    3 LOAD_CONST 1 (2)
    6 COMPARE_OP 0 (<)
    9 POP_JUMP_IF_FALSE 16
    3 12 LOAD_CONST 2 (1)
    15 RETURN_VALUE
    5 >> 16 LOAD_GLOBAL 0 (fib)
    19 LOAD_FAST 0 (n)
    22 LOAD_CONST 2 (1)
    25 BINARY_SUBTRACT
    26 CALL_FUNCTION 1
    29 LOAD_GLOBAL 0 (fib)
    32 LOAD_FAST 0 (n)
    35 LOAD_CONST 1 (2)
    38 BINARY_SUBTRACT
    39 CALL_FUNCTION 1
    42 BINARY_ADD
    43 RETURN_VALUE
    44 LOAD_CONST 0 (None)
    47 RETURN_VALUE
    translate.py
    bytecode
    interpreter
    abstract runtime
    

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81. Abstract Interpretation
    Translator runs the
    code "in the abstract"
    2 0 LOAD_FAST 0 (n)
    3 LOAD_CONST 1 (2)
    6 COMPARE_OP 0 (<)
    9 POP_JUMP_IF_FALSE 16
    3 12 LOAD_CONST 2 (1)
    15 RETURN_VALUE
    5 >> 16 LOAD_GLOBAL 0 (fib)
    19 LOAD_FAST 0 (n)
    22 LOAD_CONST 2 (1)
    25 BINARY_SUBTRACT
    26 CALL_FUNCTION 1
    29 LOAD_GLOBAL 0 (fib)
    32 LOAD_FAST 0 (n)
    35 LOAD_CONST 1 (2)
    38 BINARY_SUBTRACT
    39 CALL_FUNCTION 1
    42 BINARY_ADD
    43 RETURN_VALUE
    44 LOAD_CONST 0 (None)
    47 RETURN_VALUE
    translate.py
    bytecode
    interpreter
    abstract runtime
    

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82. Abstract Interpretation
    Translator runs the
    code "in the abstract"
    2 0 LOAD_FAST 0 (n)
    3 LOAD_CONST 1 (2)
    6 COMPARE_OP 0 (<)
    9 POP_JUMP_IF_FALSE 16
    3 12 LOAD_CONST 2 (1)
    15 RETURN_VALUE
    5 >> 16 LOAD_GLOBAL 0 (fib)
    19 LOAD_FAST 0 (n)
    22 LOAD_CONST 2 (1)
    25 BINARY_SUBTRACT
    26 CALL_FUNCTION 1
    29 LOAD_GLOBAL 0 (fib)
    32 LOAD_FAST 0 (n)
    35 LOAD_CONST 1 (2)
    38 BINARY_SUBTRACT
    39 CALL_FUNCTION 1
    42 BINARY_ADD
    43 RETURN_VALUE
    44 LOAD_CONST 0 (None)
    47 RETURN_VALUE
    translate.py
    bytecode
    interpreter
    abstract runtime
    

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83. Abstract Interpretation
    Translator runs the
    code "in the abstract"
    2 0 LOAD_FAST 0 (n)
    3 LOAD_CONST 1 (2)
    6 COMPARE_OP 0 (<)
    9 POP_JUMP_IF_FALSE 16
    3 12 LOAD_CONST 2 (1)
    15 RETURN_VALUE
    5 >> 16 LOAD_GLOBAL 0 (fib)
    19 LOAD_FAST 0 (n)
    22 LOAD_CONST 2 (1)
    25 BINARY_SUBTRACT
    26 CALL_FUNCTION 1
    29 LOAD_GLOBAL 0 (fib)
    32 LOAD_FAST 0 (n)
    35 LOAD_CONST 1 (2)
    38 BINARY_SUBTRACT
    39 CALL_FUNCTION 1
    42 BINARY_ADD
    43 RETURN_VALUE
    44 LOAD_CONST 0 (None)
    47 RETURN_VALUE
    translate.py
    bytecode
    interpreter
    abstract runtime
    

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84. Abstract Interpretation
    Translator runs the
    code "in the abstract"
    2 0 LOAD_FAST 0 (n)
    3 LOAD_CONST 1 (2)
    6 COMPARE_OP 0 (<)
    9 POP_JUMP_IF_FALSE 16
    3 12 LOAD_CONST 2 (1)
    15 RETURN_VALUE
    5 >> 16 LOAD_GLOBAL 0 (fib)
    19 LOAD_FAST 0 (n)
    22 LOAD_CONST 2 (1)
    25 BINARY_SUBTRACT
    26 CALL_FUNCTION 1
    29 LOAD_GLOBAL 0 (fib)
    32 LOAD_FAST 0 (n)
    35 LOAD_CONST 1 (2)
    38 BINARY_SUBTRACT
    39 CALL_FUNCTION 1
    42 BINARY_ADD
    43 RETURN_VALUE
    44 LOAD_CONST 0 (None)
    47 RETURN_VALUE
    translate.py
    bytecode
    interpreter
    abstract runtime
    

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85. Abstract Interpretation
    Translator runs the
    code "in the abstract"
    2 0 LOAD_FAST 0 (n)
    3 LOAD_CONST 1 (2)
    6 COMPARE_OP 0 (<)
    9 POP_JUMP_IF_FALSE 16
    3 12 LOAD_CONST 2 (1)
    15 RETURN_VALUE
    5 >> 16 LOAD_GLOBAL 0 (fib)
    19 LOAD_FAST 0 (n)
    22 LOAD_CONST 2 (1)
    25 BINARY_SUBTRACT
    26 CALL_FUNCTION 1
    29 LOAD_GLOBAL 0 (fib)
    32 LOAD_FAST 0 (n)
    35 LOAD_CONST 1 (2)
    38 BINARY_SUBTRACT
    39 CALL_FUNCTION 1
    42 BINARY_ADD
    43 RETURN_VALUE
    44 LOAD_CONST 0 (None)
    47 RETURN_VALUE
    translate.py
    bytecode
    interpreter
    abstract runtime
    

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86. Abstract Interpretation
    A Control flow graph is
    constructed
    translate.py
    bytecode
    interpreter
    abstract runtime
    

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87. Abstract Interpretation
    C Code
    The full details are "hairy"
    

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88. "You are in a maze of twisty
    little passages, all alike."
    (and a huge green fierce snake bars the way)
    

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89. Understanding the Source
    • Two different languages co-exist (same syntax)
    # file1.py
    def name2(args):
    statement
    statement
    def name3(args):
    statement
    statement
    statement
    statement
    def name1(args):
    statement
    statement
    statement
    Full Python????
    RPython????
    Which is it?
    

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90. Understanding the Source
    • Two different languages co-exist (same syntax)
    # file1.py
    def name2(args):
    statement
    statement
    def name3(args):
    statement
    statement
    statement
    statement
    def name1(args):
    statement
    statement
    statement
    Full Python????
    RPython????
    Which is it?
    (You can't look in isolation)
    

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91. Understanding the Source
    def cast_object_to_ptr(PTR, object):
    """NOT_RPYTHON: hack. The object may
    Limited to casting a given object to
    """
    if isinstance(PTR, lltype.Ptr):
    TO = PTR.TO
    else:
    TO = PTR
    ...
    • PyPy uses doc strings to help you sort it out
    • It is enforced by the translator (an assertion)
    

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92. Understanding the Source
    • Deeper question: Why would you have mixed code?
    # file1.py
    def name2(args):
    statement
    statement
    def name3(args):
    statement
    statement
    statement
    statement
    def name1(args):
    statement
    statement
    statement
    RPython
    Python
    • Head throbbing...
    

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93. Execution Contexts
    # file1.py
    def name2(args):
    statement
    statement
    def name3(args):
    statement
    statement
    statement
    statement
    def name1(args):
    statement
    statement
    statement
    Translation (Python) Executable (C)
    

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94. Execution Contexts
    # file1.py
    def name2(args):
    statement
    statement
    def name3(args):
    statement
    statement
    statement
    statement
    def name1(args):
    statement
    statement
    statement
    Translation (Python) Executable (C)
    • At translation, the code separates
    Metaprogramming Implementation
    • decorators
    • metaclasses
    • exec()
    

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95. Example
    def decorator(func):
    statements
    ...
    def wrapper(*args,**kwargs):
    statements
    ...
    return func(*args,**kwargs)
    return wrapper
    @decorator
    def func(args):
    statements
    ...
    

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96. Example
    def decorator(func):
    statements
    ...
    def wrapper(*args,**kwargs):
    statements
    ...
    return func(*args,**kwargs)
    return wrapper
    @decorator
    def func(args):
    statements
    ...
    Python
    RPython
    Python
    RPython
    

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97. Rules of Thumb
    • Code that executes at import time can
    make use of all Python features
    • Code reachable through the entry point
    (target) is RPython
    • Keeping it straight is hard (for me anyways)
    

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98. But Wait, There's More!
    

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99. Foreign Code
    • PyPy is written in "Python", but can access
    external C code and libraries
    • os, math, time, threads, etc.
    • There is a highly developed FFI mechanism
    • Plus a configuration system (think autoconf)
    

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100. Example
     (Accessing Foreign Functions)
     

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101. A Quandary
     • How do I end this talk?
     • I've only talked about RPython
     • When do we get to the PyPy?
     

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102. A Realization
     I still don't know know
     how PyPy works!
     Score: PyPy: 1 Dave: 0
     

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103. A Deeper Realization
     I don't even know how
     CPython works!
     

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104. WAT!?!
     WAT!?!
     

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105. A Clarification
     I do know how to use the
     tools that make CPython
     

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106. A Clarification
     I do know how to use the
     tools that make CPython
     • ANSI C
     • Makefiles
     • Algorithms
     • Data Structures
     

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107. The Challenge
     PyPy has a different set of tools
     • RPython
     • translate.py
     • Metaprogramming
     • Foreign Functions
     

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108. So how to end this talk?
     

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109. Wait! I used to be an evil professor!
     

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110. Figuring out how PyPy works
     is left as an exercise!
     (You'll learn a lot)
     

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111. Postscript
     

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112. Postscript
     Let's talk about Ruby!
     threads.each { |aThread| aThread.join }
     

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113. Breaking GILs
     • As you know, I like breaking GILs
     • You know, global interpreter locks
     • As in threads and stuff...
     • I love it!
     

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114. A Benchmark
     • Message-passing with a CPU-bound thread
     C : 1.11s
     Python 2.7 : 1.60s
     Ruby 1.9 : 5839.4s
     • Don't concern yourself with the details
     • Ruby 3600x slower than Python?
     • What's that all about? Let's go tinker!
     

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115. Tinkering with Ruby
     • It was pretty straightforward
     • Finding the GIL didn't take long
     • An afternoon of fiddling around
     (Search for my talk at RuPy 2011)
     • Caused by a more extreme case of the
     thread priority inversion that's in Python 3.3
     

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116. Just to be clear...
     I couldn't write a real Ruby
     program to save my life right now.
     

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117. A PyPy Benchmark
     • A similar message-passing benchmark
     Python 2.7 : 15.6s
     PyPy-1.6 : 6689.2s (428x slower)
     • Huh? What's that all about?
     • No idea! Or even how to look.
     • That is the whole reason for this talk
     

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118. Parting Words
     • Can you tinker with PyPy?
     • Honest answer: I still don't know
     • Should you try to go tinker with it anyways?
     • YES!
     • You will find interesting things inside
     

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119. "My God, it's full of stars!"
     

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120. "My God, it's full of stars!"
     (or VMs?)
     

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121. Thanks!
     • Hope you learned at least one new thing
     • Special thanks:
     • Alex Gaynor
     • Maciej Fijalkowski
     • Chipy
     • Twitter: @dabeaz
     

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