R1D2 Profiling Python
I spent some time fiddling with Lambda. The code now more or less works.
Moving on to optimization, I started reading about profiling in python.
I’ve been using time to see how long the script takes to run. Using cProfile allows you to see how long each specific method call in your application takes to run. Running this on old_posts.py produced the following output.
The following command executes the script under profiling, sorts the results by time and saves the output to a text file.
python -m cProfile -s time old_posts.py > profile.txt
289508 function calls (286008 primitive calls) in 6.616 seconds
Ordered by: internal time
ncalls tottime percall cumtime percall filename:lineno(function)
284 5.495 0.019 5.495 0.019 {method ‘read’ of ‘_ssl._SSLSocket’ objects}
24 0.514 0.021 0.514 0.021 {method ‘do_handshake’ of ‘_ssl._SSLSocket’ objects}
24 0.157 0.007 0.157 0.007 {method ‘connect’ of ‘_socket.socket’ objects}
24 0.123 0.005 0.123 0.005 {method ’load_verify_locations’ of ‘_ssl._SSLContext’ objects}
24 0.027 0.001 0.030 0.001 connectionpool.py:410(close)
24 0.015 0.001 0.015 0.001 {built-in method _socket.gethostbyname}
173 0.015 0.000 0.015 0.000 {built-in method marshal.loads}
22 0.013 0.001 0.013 0.001 decoder.py:345(raw_decode)
24 0.012 0.001 0.013 0.001 {built-in method _socket.getaddrinfo}
20 0.012 0.001 0.012 0.001 {built-in method _imp.create_dynamic}
486/483 0.009 0.000 0.017 0.000 {built-in method builtins.build_class}
1019 0.007 0.000 0.007 0.000 {built-in method posix.stat}
24 0.007 0.000 0.007 0.000 {built-in method _scproxy._get_proxy_settings}
189/1 0.005 0.000 6.616 6.616 {built-in method builtins.exec}
2472 0.005 0.000 0.008 0.000 parser.py:68(get_token)
1 0.004 0.004 0.004 0.004 {method ‘read’ of ‘_io.TextIOWrapper’ objects}
266/80 0.003 0.000 0.010 0.000 sre_parse.py:470(_parse)
206 0.003 0.000 0.023 0.000 parser.py:622(_parse)
460 0.003 0.000 0.015 0.000 <frozen importlib._bootstrap_external>:1233(find_spec)
14107 0.003 0.000 0.005 0.000 {built-in method builtins.isinstance}
601 0.003 0.000 0.003 0.000 {built-in method new of type object at 0x107136800}
173 0.003 0.000 0.004 0.000 <frozen importlib._bootstrap_external>:830(get_data)
24 0.003 0.000 0.003 0.000 {built-in method _scproxy._get_proxies}
24068/23811 0.002 0.000 0.004 0.000 {built-in method builtins.len}
3615 0.002 0.000 0.007 0.000 os.py:664(getitem)
3936 0.002 0.000 0.011 0.000 _collections_abc.py:742(iter)
495/71 0.002 0.000 0.010 0.000 sre_compile.py:64(_compile)
1962 0.002 0.000 0.005 0.000 {built-in method builtins.min}
3830 0.002 0.000 0.003 0.000 enum.py:515(new)
48 0.002 0.000 0.002 0.000 {method ‘set_ciphers’ of ‘_ssl._SSLContext’ objects}
148 0.002 0.000 0.002 0.000 {built-in method posix.getcwd}
10300 0.002 0.000 0.003 0.000 parser.py:320(<genexpr>)
3843 0.002 0.000 0.008 0.000 enum.py:265(call)
6335 0.002 0.000 0.002 0.000 {built-in method builtins.getattr}
3642/3195 0.002 0.000 0.021 0.000 {built-in method builtins.hasattr}
1563 0.002 0.000 0.005 0.000 enum.py:801(and)
225 0.002 0.000 0.002 0.000 sre_compile.py:250(_optimize_charset)
4681 0.002 0.000 0.002 0.000 sre_parse.py:232(__next)
6892 0.002 0.000 0.002 0.000 {method ‘decode’ of ‘bytes’ objects}
173 0.002 0.000 0.002 0.000 {method ‘read’ of ‘_io.FileIO’ objects}
By default the wordpress API returns 10 posts per page. Updating this value to 100 decreased the time spent making network calls and overall function calls by almost 50%!
Results after per_page=100
145834 function calls (142393 primitive calls) in 2.679 seconds
Ordered by: internal time
ncalls tottime percall cumtime percall filename:lineno(function)
186 2.364 0.013 2.364 0.013 {method ‘read’ of ‘_ssl._SSLSocket’ objects}
5 0.073 0.015 0.073 0.015 {method ‘do_handshake’ of ‘_ssl._SSLSocket’ objects}
5 0.043 0.009 0.043 0.009 {method ‘connect’ of ‘_socket.socket’ objects}
5 0.026 0.005 0.026 0.005 {method ’load_verify_locations’ of ‘_ssl._SSLContext’ objects}
Lessons
Profiling is great. Instead of guessing why my code is slow, I can ask python to tell me explicitly.Most importantly, for the real world. AWS Lambda bills by the nearest 100 milliseconds.
Duration is calculated from the time your code begins executing until it returns or otherwise terminates, rounded up to the nearest 100ms. The price depends on the amount of memory you allocate to your function.So in a model like this, reducing the total time for your code to run from 6 seconds to 3 seconds will also reduce your bill by 50%.
Thank you for reading! Share your thoughts with me on bluesky, mastodon, or via email.
Check out some more stuff to read down below.
Most popular posts this month
- SQLite DB Migrations with PRAGMA user_version
- My Custom Miniflux CSS Theme
- Making cgit Pretty
- Using cgit
- Convert Markdown to PDF in Sublime Text
Recent Favorite Blog Posts
This is a collection of the last 8 posts that I bookmarked.
- Rewrote my blog with Zine from Drew DeVault's blog
- A eulogy for Vim from Drew DeVault's blog
- Pluralistic: AI "journalists" prove that media bosses don't give a shit (11 Mar 2026) from Pluralistic: Daily links from Cory Doctorow
- Offline 23 hours a day from Derek Sivers blog
- Pluralistic: California can stop Larry Ellison from buying Warners (28 Feb 2026) from Pluralistic: Daily links from Cory Doctorow
- On Alliances from Smashing Frames
- Acting ethically in an imperfect world from Smashing Frames
- Diffusion of Responsibility from Smashing Frames
Articles from blogs I follow around the net
Pluralistic: Demand destruction vs fuel-superceding infrastructure (04 May 2026)
Today's links Demand destruction vs fuel-superceding infrastructure: Will Trump hormuz us into the full Gretacene? Hey look at this: Delights to delectate. Object permanence: Beck, Scientologist; Citizen journalism; Podcast-killing treaty; US x Kiwi copyri...
via Pluralistic: Daily links from Cory Doctorow May 4, 20261993 communal internet shaped me: https://sive.rs/netizen
1993 communal internet shaped me: https://sive.rs/netizen
via Derek Sivers May 4, 2026The 1990s called and they want their dialog box back
This is perhaps my favourite feature in Lightroom. You press ⇧T, you draw a few lines, and presto – your photo is now even: This is doubly magical to me. The first part is that this is even possible – that you can straighten the photo in both dimensions af...
via Unsung May 3, 2026Generated by openring