7 posts tagged “threading”
2025
Hypothesis is now thread-safe (via) Hypothesis is a property-based testing library for Python. It lets you write tests like this one:
from hypothesis import given, strategies as st @given(st.lists(st.integers())) def test_matches_builtin(ls): assert sorted(ls) == my_sort(ls)
This will automatically create a collection of test fixtures that exercise a large array of expected list and integer shapes. Here's a Gist demonstrating the tests the above code will run, which include things like:
[]
[0]
[-62, 13194]
[44, -19562, 44, -12803, -24012]
[-7531692443171623764, -109369043848442345045856489093298649615]
Hypothesis contributor Liam DeVoe was recently sponsored by Quansight to add thread safety to Hypothesis, which has become important recently due to Python free threading:
While we of course would always have loved for Hypothesis to be thread-safe, thread-safety has historically not been a priority, because running Hypothesis tests under multiple threads is not something we see often.
That changed recently. Python---as both a language, and a community---is gearing up to remove the global interpreter lock (GIL), in a build called free threading. Python packages, especially those that interact with the C API, will need to test that their code still works under the free threaded build. A great way to do this is to run each test in the suite in two or more threads simultaneously. [...]
Nathan mentioned that because Hypothesis is not thread-safe, Hypothesis tests in community packages have to be skipped when testing free threaded compatibility, which removes a substantial battery of coverage.
Now that Hypothesis is thread-safe another blocker to increased Python ecosystem support for free threading has been removed!
2024
Free-threaded CPython is ready to experiment with! The Python 3.13 beta releases that include a "free-threaded" version that removes the GIL are now available to test! A team from Quansight Labs, home of the PyData core team, just launched py-free-threading.github.io to help document the new builds and track compatibility with Python's larger ecosystem.
Free-threading mode will not be enabled in Python installations by default. You can install special builds that have the option enabled today - I used the macOS installer and, after enabling the new build in the "Customize" panel in the installer, ended up with a /usr/local/bin/python3.13t binary which shows "Python 3.13.0b3 experimental free-threading build" when I run it.
Here's my TIL describing my experiments so far installing and running the 3.13 beta on macOS, which also includes a correction to an embarrassing bug that Claude introduced but I failed to catch!
2021
The GIL and its effects on Python multithreading (via) Victor Skvortsov presents the most in-depth explanation of the Python Global Interpreter Lock I’ve seen anywhere. I learned a ton from reading this.
2018
Intro to Threads and Processes in Python (via) I really like the diagrams in this article which compares the performance of Python threads and processes for different types of task via the excellent concurrent.futures library.
2009
Introducing Yardbird. I absolutely love it—an IRC bot built on top of Twisted that passes incoming messages off to Django code running in a separate thread. Requests and Response objects are used to represent incoming and outgoing messages, and Django’s regex-based URL routing is used to dispatch messages to different handling functions based on their content.
jessenoller.com—python magazine. Jesse Noller has been sharing his articles originally published in Python Magazine. Topics include SSH programming with Paramiko, context managers and the with statement and an excellent explanation of Python’s threading support and the global interpreter lock.
2007
Thread Synchronization Mechanisms in Python. Locks, RLocks, Semaphores, Events and Conditions as explained by Fredrik Lundh.