This document discusses PyPy, an alternative implementation of the Python language that aims to be faster than CPython while maintaining compatibility. It covers how to install PyPy, notes on garbage collection and C extensions, techniques for optimizing code for PyPy like focusing on static types, and the status of Python 3 support in PyPy.

1. Ronan Lamy
MAGICALLY RUN YOUR
CODE FASTER WITH
PYPY

2. ABOUT ME
PyPy core dev
Python consultant and freelance developer
Contact:
Ronan.Lamy@gmail.com
@ronanlamy

3. ABOUT PYPY
http://pypy.org
"PyPy is a fast, compliant alternative
implementation of the Python language"

4. Guido van Rossum, PyCon 2015
"If you want your code magically to run
faster, you should probably just use PyPy"

5. PLAN
Make it work
Make it fast
What about Python 3?

6. MAKE IT WORK

7. INSTALLATION OPTIONS
From the package manager
On Ubuntu, use the PPA: ppa:pypy/ppa
Official binaries from
Portable PyPy (Linux only):
pyenv:
http://pypy.org/download.html
https://github.com/squeaky-
pl/portable-pypy
https://github.com/yyuu/pyenv

8. USE VIRTUALENV
$ virtualenv ­p path/to/pypy pypy­env
$ . pypy­env/bin/activate
$ python ­m pip install ­U pip

9. GARBAGE COLLECTION
CPython has reference counting
Object cleanup is deterministic (sometimes!)
PyPy is garbage collected
Object cleanup happens “randomly”

10. GARBAGE COLLECTION ISSUES
Don’t use __del__
Always close resources
Use with: blocks
-X track-resources

11. C EXTENSIONS
You don’t need to write C!
Use cffi
cpyext: emulation of CPython C API

12. C EXTENSION ISSUES
Usually works (new!)
If not:
Use (or write!) cffi alternative
Stub/rewrite in Python

13. MAKE IT FAST

14. CPYTHON

15. C compiler
CPython
source
(C)
Python
code
Bytecode
Byte
interp.
python
Do stuff or whatever

16. PYPY

17. RPython toolchain
PyPy
source
(RPython)
Python
code
Bytecode
Byte
interp.
Tracing
Machine
code
pypy
Do stuff or whatever

18. OPTIMISING FOR PYPY
Aim for mostly-static types
Function calls are ~free
Instance maps
List strategies
Dicts are slow

19. BENCHMARKING
Measure, don’t guess!
Your tests are not a good benchmark
“WARNING: timeit is a very unreliable tool. use perf or
something else for real measurements”

20. PROFILING
vmprof

21. PYTHON 3

22. 3.3
Community funded
pypy3.3-v5.5.0 released 12 October 2016
Last 3.3 release

23. 3.5
Mozilla Open Source Support grant
Milestones:
1. Interpreter changes
2. C-API
3. ssl and other stdlib modules
4. Benchmarking and optimisation

24. THE END

25. EXTRAS

26. CFFI
Design principle: users only need to know C and Python
Bundled with PyPy
Performance: OK on CPython, fast on PyPy
Docs: http://cffi.readthedocs.org

27. CFFI EXAMPLE
example_build.py
from cffi import FFI
ffi = FFI()
ffi.cdef("""
int foo(int** X, int m, int n);
""")
ffi.set_source("_example", '#include "foo.h"')
if __name__ == "__main__":
ffi.compile()
example.py
from _example import ffi, lib
x = ffi.new('int[42][42]')
lib.foo(x, 42, 42)