The document is advertising for Python developers to join the team of a booking site for campsites and caravan parks. The company is seeking candidates to speak with them at a PyPy demo night or apply via their website. The company is leading in its market, receiving 65k daily visits and £6m in annual bookings, and has a team of 15 based in west London.

1. Looking for Python
developers!
Speak to us at PyPy
demo night or visit
www.pitchup.com/jobs
Python / Django
Postgres
Celery
Redis
nginx
memcache
Jquery
Solr
S3
Leading booking site for campsites and caravan
parks, founded in 2009 by lastminute.com alumni
● 65k visits / day, £6m bookings / year
● 650 bookable sites
● Huge market
○ 26k campsites and 300m bednights in Europe
○ 600m bednights in US
○ 47% more bednights than hotels (GB)
○ More trips to campsites than holidays to France +
Spain combined (GB)
● Team of 15, based in west London

2. Welcome to the PyPy Demo Evening
Laurence Tratt
2013-08-27
1 / 5 http://soft-dev.org/

3. Why are we here?
2 / 5 http://soft-dev.org/

4. What do we do?
(l-r) Vasudevan, Bolz, Tratt, Barrett, Diekmann
3 / 5 http://soft-dev.org/

5. What do we do?
• Aim: identify important challenges in software
development.
3 / 5 http://soft-dev.org/

6. What do we do?
• Aim: identify important challenges in software
development.
• Strengths: language design and implementation.
3 / 5 http://soft-dev.org/

7. What do we do?
• Aim: identify important challenges in software
development.
• Strengths: language design and implementation.
• Immediate benefits: faster VMs.
3 / 5 http://soft-dev.org/

8. What do we do?
• Aim: identify important challenges in software
development.
• Strengths: language design and implementation.
• Immediate benefits: faster VMs.
• Long-term benefits: language composition.
3 / 5 http://soft-dev.org/

9. This evening
1 Carl Friedrich Bolz PyPy overview.
2 Lukas Diekmann Storage strategies.
3 Maciej Fijalkowski NumPy.
4 Armin Rigo Software Transactional Memory
(STM).
5 Edd Barrett Language composition using
meta-tracing.
4 / 5 http://soft-dev.org/

10. Can you help?
• Contributors.
5 / 5 http://soft-dev.org/

11. Can you help?
• Contributors.
• Resources.
• Software Freedom Conservancy
5 / 5 http://soft-dev.org/

12. A Very Brief Introduction to PyPy
Carl Friedrich Bolz
PyPy Demo Evening, King’s College London,
August 27, 2013
Carl Friedrich Bolz A Very Brief Introduction to PyPy

13. CPython is slow
CPython 1-3 orders of magnitude slower than C
BinaryTrees
Dhrystone
FannkuchRedux
Fasta
Knucleotide
Mandelbrot
Nbody
RegexDNA
RevComp
Richards
SpectralNorm
0.1
1
10
100
1000
SlowerthanC,lowerisbetter
C
Java
Cpython
Carl Friedrich Bolz A Very Brief Introduction to PyPy

14. Reasons for Bad Performance
interpretation overhead
late binding
dispatching
boxing
Carl Friedrich Bolz A Very Brief Introduction to PyPy

15. Enter PyPy
a modern efficient implementation of Python
Carl Friedrich Bolz A Very Brief Introduction to PyPy

16. Enter PyPy
a modern efficient implementation of Python
open source, MIT license
written in Python itself, then bootstrapped to C
uses a tracing JIT compiler to produce machine code at
runtime
Carl Friedrich Bolz A Very Brief Introduction to PyPy

17. Performance of PyPy
significantly faster than CPython, typically in the same order of
magnitude than C
BinaryTrees
Dhrystone
FannkuchRedux
Fasta
Knucleotide
Mandelbrot
Nbody
RegexDNA
RevComp
Richards
SpectralNorm
0.1
1
10
100
1000
SlowerthanC,lowerisbetter
C
Java
PyPy
CPython
Carl Friedrich Bolz A Very Brief Introduction to PyPy

18. Performance of PyPy
significantly faster than CPython, typically in the same order of
magnitude than C
BinaryTrees
Dhrystone
FannkuchRedux
Fasta
Knucleotide
Mandelbrot
Nbody
RegexDNA
RevComp
Richards
SpectralNorm
0.1
1
10
100
1000
SlowerthanC,lowerisbetter
C
Java
PyPy
CPython
on average about 6.3 faster than CPython
Carl Friedrich Bolz A Very Brief Introduction to PyPy

19. Demo
Carl Friedrich Bolz A Very Brief Introduction to PyPy

20. Architecture
Python interpreter written in RPython
JIT-compiler automatically added via meta-tracing
Carl Friedrich Bolz A Very Brief Introduction to PyPy

21. Status
Python 2.7.3 support, 2.7.4 coming soon
beta-level support for Python 3.2, more coming eventually
pure Python code fully supported, please report as bug if
not
Carl Friedrich Bolz A Very Brief Introduction to PyPy

22. Status
Python 2.7.3 support, 2.7.4 coming soon
beta-level support for Python 3.2, more coming eventually
pure Python code fully supported, please report as bug if
not
C extension modules partially supported, if they are
well-behaved
they are slow
use cffi (a ctypes replacement) instead
Carl Friedrich Bolz A Very Brief Introduction to PyPy

23. Questions?
PyPy is a fast JITted Python implementation
(if something is not fast, please report it as a bug)
open source under MIT license
http://pypy.org
Carl Friedrich Bolz A Very Brief Introduction to PyPy

24. Storage Strategies for Fast Containers
Lukas Diekmann
August, 27 2013
1 / 6 http://soft-dev.org/

25. Collection strategies
introduced in PyPy 1.9
optimisation of collections for certain data types
improving speed
reducing memory
2 / 6 http://soft-dev.org/

26. Idea
typical programs have homogeneously types collections
create optimised versions of collections for certain types
so far:
lists: ints, floats, strings/unicode
sets: ints, floats, strings/unicode
dicts: ints, strings/unicode
3 / 6 http://soft-dev.org/

27. Optimisations
collections automatically change to most efficient strategy
store elements more memory efficiently
fast elements access
4 / 6 http://soft-dev.org/

28. Further optimisations
collection creation and initalisation
split(d), set([1,2,3])
type based operations:
contains, difference, issubset
special strategies
RangeListStrategy: calculates elements on the fly
Tracing JIT interaction:
faster (low-level) comparisons, remove type checks
5 / 6 http://soft-dev.org/

29. Results
paper at OOPSLA
on average ∼18% speedup
∼6% less memory usage
more info at http://soft-dev.org/pubs/
6 / 6 http://soft-dev.org/

30. Numpy on PyPy
Maciej Fijałkowski
King’s College London
August 27 2013
fijal Numpy on PyPy

31. Goals
fully compliant numpy replacement for PyPy
fast looped operations
fast vectorized operations
fijal Numpy on PyPy

32. Why?
fast looping
single language
fijal Numpy on PyPy

33. Model
some programs have numerical kernels that can
be written in C
some don’t
http://arxiv.org/abs/1301.1334
image manipulation demo
abstraction unfriendly
fijal Numpy on PyPy

34. Status
fast looped operations
ok vectorized operations
fijal Numpy on PyPy

35. Future goals
finish numpy
make it fast
make it compatible with more software
(matplotlib, scipy)
fijal Numpy on PyPy

36. Funding
about $20k left
we likely need more
behind schedule, but not behind budget
fijal Numpy on PyPy

37. Q&A
Thank you!
fijal Numpy on PyPy

38. Software Transactional Memory on PyPy

39. Pseudo-Goal
“Kill the GIL”
GIL = Global Interpreter Lock

40. Real Goals
Multi-core programming
But reasonable multi-core programming
Using the recent model of Transactional Memory

41. PyPy-STM
An executable pypy-stm which uses internally Software
Transactional Memory
Optimistically run multiple threads in parallel
The only new feature is atomic:
with atomic:
piece of code...

42. Example of higher-level API
def work(...):
...
several more calls to:
transaction.add(work, ...)
...
Starts N threads, scheduling work() calls to them
Each work() is done in an atomic block
Multi-core, but as if all the work() are done sequentially

43. Status
Kind of working without the JIT
Roughly three times slower (you need four cores to see benefits)
Working on the JIT support

44. Q&A
Thank you!
Budget of $10k left, likely more needed too

45. Unipycation
Combining Prolog and Python
Edd Barrett
August 27, 2013
1 / 9 http://soft-dev.org/

46. Our Goal
The softdev team is exploring language compositions.
Ideally our compositions should be:
Easy to implement.
Transparent (as possible) to the user-programmer.
High performance.
Can meta-tracing help?
2 / 9 http://soft-dev.org/

47. Unipycation: A Language Composition Experiment
PyPy + Pyrolog = Unipycation
Unipycation
Both interpreters implemented in RPython.
About 600 LoC of integration code.
A few months to develop.
Languages communicate via an API.
No syntax integration yet.
3 / 9 http://soft-dev.org/

48. Why?
Explore composition of opposing paradigms.
Evaluate RPython as a language composition framework.
Performance/ease of development.
Composition with many realistic applications.
Example Scenario
Data acquisition by JSON/XML/Sqlite.
Easy in Python, not easy in Prolog.
Some kind of knowledge inference based upon data.
Perhaps not so easy in Python, trivial in Prolog.
Visualisation of Results.
Easy in Python, lack of library support in Prolog.
4 / 9 http://soft-dev.org/

49. Example
Suppose we have a directed graph (London Underground?):
a c
b
d
e
d
g
And we need to ask questions like:
Where can I get to from ’b’ via at most 4 nodes and how?
5 / 9 http://soft-dev.org/

50. This is Easy with Prolog
path.pl:
edge(a, c). edge(c, b). edge(c, d). edge(d, e).
edge(b, e). edge(c, f). edge(f, g). edge(e, g).
edge(g, b).
path(From , To , MaxLen , Nodes) :-
path(From , To , MaxLen , Nodes , 1).
path(Node , Node , _, [Node], _).
path(From , To , MaxLen , [From | Ahead ], Len) :-
Len < MaxLen , edge(From , Next),
Len1 is Len + 1,
path(Next , To , MaxLen , Ahead , Len1).
query: path(b, To, 4, Path).
6 / 9 http://soft-dev.org/

51. Example: Python → Prolog
from uni import Engine
engine = Engine.from_file (" path.pl")
paths = engine.db.path.iter
for (to , nodes) in paths ("b", None , 4, None):
print ("To %s via %s" % (to , nodes))
To b via [’b’]
To e via [’b’, ’e’]
To g via [’b’, ’e’, ’g’]
To b via [’b’, ’e’, ’g’, ’b’]
Calling from Prolog to Python also possible. E.g.
python:somefunc(blah)
7 / 9 http://soft-dev.org/

52. Performance
8 / 9 http://soft-dev.org/

53. In Summary
Compositions are relatively easy to implement with RPython.
We were able to implement a fairly transparent API-like interface.
Performance promising.
Further Reading
https://bitbucket.org/vext01/pypy
http://soft-dev.org/
9 / 9 http://soft-dev.org/

54. Looking for Python
developers!
Speak to us at PyPy
demo night or visit
www.pitchup.com/jobs
Python / Django
Postgres
Celery
Redis
nginx
memcache
Jquery
Solr
S3
Leading booking site for campsites and caravan
parks, founded in 2009 by lastminute.com alumni
● 65k visits / day, £6m bookings / year
● 650 bookable sites
● Huge market
○ 26k campsites and 300m bednights in Europe
○ 600m bednights in US
○ 47% more bednights than hotels (GB)
○ More trips to campsites than holidays to France +
Spain combined (GB)
● Team of 15, based in west London