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Merged
kennethreitz merged 5 commits into from
Jan 15, 2012
Merged

Speed file updates #73

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d139b34
Add links to understand the GIL
rday Dec 30, 2011
13a9830
fix link markup
rday Dec 30, 2011
87bb636
Merge remote branch 'original/master'
rday Jan 5, 2012
96521d2
Add benchmarks
rday Jan 5, 2012
2111060
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rday Jan 5, 2012
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44 changes: 40 additions & 4 deletions docs/scenarios/speed.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,32 @@ Speed

CPython, the most commonly used implementation of Python, is slow for CPU bound tasks. `PyPy`_ is fast.

.. todo:: Fill in stub for Speed comparisons
Using a slightly modified version of `David Beazleys`_ CPU bound test code(added loop for multiple tests), you can see the difference between CPython and PyPy's processing.

::

PyPy
$ ./pypy -V
Python 2.7.1 (7773f8fc4223, Nov 18 2011, 18:47:10)
[PyPy 1.7.0 with GCC 4.4.3]
$ ./pypy measure2.py
0.0683999061584
0.0483210086823
0.0388588905334
0.0440690517426
0.0695300102234

::

CPython
$ ./python -V
Python 2.7.1
$ ./python measure2.py
1.06774401665
1.45412397385
1.51485204697
1.54693889618
1.60109114647

Context
:::::::
Expand All @@ -12,7 +37,13 @@ Context
The GIL
-------

`The GIL`_ (Global Interpreter Lock) is how Python allows multiple threads to operate at the same time. Python's
memory management isn't entirely thread-safe, so the GIL is requried to prevents multiple threads from running
the same Python code at once.

David Beazley has a great `guide`_ on how the GIL operates. He also covers the `new GIL`_ in Python 3.2. His
results show that maximizing performance in a Python application requires a strong understanding of the GIL,
how it affects your specific application, how many cores you have, and where your application bottlenecks are.

C Extentions
------------
Expand All @@ -21,8 +52,8 @@ C Extentions
The GIL
-------



`Special care`_ must be taken when writing C extensions to make sure you register your threads
with the interpreter.

C Extentions
::::::::::::
Expand Down Expand Up @@ -57,4 +88,9 @@ Multiprocessing
---------------


.. _`PyPy`: http://pypy.org
.. _`PyPy`: http://pypy.org
.. _`The GIL`: http://wiki.python.org/moin/GlobalInterpreterLock
.. _`guide`: http://www.dabeaz.com/python/UnderstandingGIL.pdf
.. _`New GIL`: http://www.dabeaz.com/python/NewGIL.pdf
.. _`Special care`: http://docs.python.org/c-api/init.html#threads
.. _`David Beazleys`: http://www.dabeaz.com/GIL/gilvis/measure2.py